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Systematic Literature Review How to Empower Data Driven Decision Making
This ticket price includes drinks and hors d'ouevres before dinner. Additional forms may be obtained by photocopying this sheet. To ensure availability and quoted rates, all reservation requests prior to Sept. Telephone reservations will be accepted after Sept. Please call the hotel reservation department. Please send a check with this form to the hotel or indicate a credit card number. Complete this torm or type In dark ink only. Use separate form for each registrant.
Warrendale, PA Print your name as you want it to appear on your badge. Hon fo,m. Iong with 'h. I, Ady. Uon to,m m. AIME memDe, file. Hon torm ,ppe. Honslncludes pa,l. Fo, Ilrsl cl,.. Pay lha. Smith Topic: ''Atlas Never Shrugged" Over the past quarter century, public support for heavy industries has eroded and the United States has moved into a post-industrial era. Among those industries most heavily affected have been those involved in the first part of the materials cycle - exploration, mining, and smelting.
Loss of public support has resulted in pejorative government regulations. Unless public attitudes and government actions are modified, the first part of the materials cycle will not survive as a major domestic industry. The health of those industries involved in the remainder of the materials cycle depends in large part upon the development and utilization of new technology and the ability of industrial leaders to marshal public support for their endeavors. The objective of this four-session symposium is to enhance the interaction between the materials processing and nondestructive evaluation communities. Topics of interest include the development and application of NDE in all aspects of materials processing - solidification casting and welding, powder metallurgy, solid state phase transformations, heat treating, shaping, residual stress, and surface modifications.
Emphasis will be placed on correlating processing-structure properties of metals, ceramics and polymers with NDE in conjunction with conventional metallurgical analysis. About the Lecturer: Dr. Smith received his B. He served as department head of metallurgical engineering and coordinator of research at Michigan Technological University and was President of Michigan Tech from until This four-session symposium will address the question of what problems will arise when the dimensions of the active components on a semiconductor chip become significantly smaller than one micron.
The authors will speak about such topics as the breakdown of the classical theory of transporting an electrical signal and the frequently different crystal structures which occur when a deposit on a substrate involves relatively few atoms. The broad scope of this symposium will bring together research and development workers in such fields as catalysis, materials science and semi-conductor physics. In this four-session symposium the techniques of computer simulation are applied to various important interfacial problems in solids. Properties such as structure, energy, segregation, thermodynamics, phase transitions, and cracking will be discussed. This five-session symposium will involve authors from ten countries. Thirty-one papers will focus on the factors which lead to the existence of a threshold stress intensity for growth of long and short fatigue cracks.
The contributions of mechanical, metallurgical, and environmental variables to the threshold will also be presented. Emphasis of the symposium will be on gaining a better understanding of the origins of this phenomena and how the various factors influencing it may be better separated and analytically described. A two-session symposium will contain papers describing recent experimental and theoretical results on fluid flow behavior during the solidification of single and polyphase materials. Included are discussions of the effects of flow fields on solute and thermal transport, interface stability, and particle redistribution, as well as the manipulation of composition, phase uniformity and material properties by natural and forced convection gravitational and magnetic fields.
The modeling and simulation of fluid flow phenomena are also examined. This four-session symposium deals with the effects of texture and microstructure in determining the properties of metals which have been stressed to large plastic strains. In addition, two sessions of the symposium will deal with super plastic forming. The following topics will be covered during this four-session symposium: mass transport-based models for local crack chemistry; modeling relating local chemical reactions to brittle crack advance, new experimental techniques for characterization or simulation of crack tip chemistry and transient reactions, mechanics-based and metallurgical considerations relevant to local chemistry and related cracking, initiation and early growth stages of cracking, and methods for combat- Ing crack and prediction life based on analyses of local chemistry.
This four-session symposium will emphasize research in broad areas of ferrous phase transformations and will serve to summarize recent theoretical and experimental advances since when the Ferrous Metallurgy Committee last sponsored the symposium "Decomposition of Austenite by Diffusional Processes. The symposium will center around several invited papers that will be augmented by a limited number of short talks on current research. Select your own travel dates NO restrictions NO limited seating capacity reo strictions as in other sp"cial fares.
NO length of stay requirements. Lowest available regular fares on al1 other airlines. Monday through Friday. Central Standard Time, 10r more information and reservations. The contracts for such services are between the attendees and the suppliers. TMS does not assume responsibility for the performance rendered by the suppliers or for any injury. Along wilh the more than 70 other titles, we offer you the authors and editors who arc front-runners in the field of metallurgy. Remember, as a member of The Metallurgical Society you will enjoy substantial discounts on all TMS publications, in addition to a wide variety of member services provided. Complete a membership application and start saving today!
Ask for a free copy of our newest publication catalog, ! Order No. The 22 papers In thIs proceedIngs are dlplded Into three sections: models of local structure. The focus of the oolume IS modeling the local slruelure In order! Dform a basIS for relating Slruc- ture and properlles. The three areas addressed are: thermodynamics and kInetics: physical and chemical properties. Abbas-c:hlan and S. Koczak and Gregory J. E:dlted by Subhash C. Proceedings of a symposium held al Ihe th Annual Meeting. C06 MeehanlCiI Beha. Hack and Maurlee F. Proceedings of a symposIum held at the I! The processIng effects of flber composUlon on mechanIcal and physical properties are discllssed In these 22 papers.
Bramfltt and P. ContaIns 29 papers detatl1ng research and productIon lesUng of metal deformation categorIzed In the four areas of formabtl1t! J lesllng. German and K. October EmphasIzes tI,e pro. Edited by Hubert I. DaVid E. Robert R. MarvIn Weyman. August EmphasIs better underslandlng of structural and composlllonalfeatures of austenlle and their Influence on subsequent transformation. Hon wilh. If elect OMl , to accept alaclion. I Strip Product. In High Temp.
Tit anium AllOy. Titanium A lloys II Deform. In Environment A. Hgue C.. Phase Translormatlons in Ferrous AllOy. Properti es of Nontr. Diagram D,t. II Char'Cle Ch. Ctefitation' Behavior 0 1 Mat er l. IV Metal Matrl" Com. Mech,nlcal Behevlor , Phase Tr,n. Wea r Melting and Solidi fi c. Smith 80th Birthday Symposium on Microstructure I Properties and Transformations Smith "Atlas Never Shrugged" Over the past quarter century , public support for heavy industries has eroded and the United States has moved into a post-industrial era. Among those industries most heavily affected have been those involved in the first part of the materials cycle--exploration , mining , and smelting.
Session Chairman: Professor L. Girfalco, University of Pennsylvania, Dept. Yi-Qun Gao and Sung H. Activation energy was obtained from Kissinger plot as well as isothermal annealing. Glass forming tendency of binary Pt systems will be presented and discussed with existing models. Partially supported by the Office of Naval Research. The hydrogen to metal ratio is shown to decrease with increasing electron to atom ratio. Brotzen and P. Recent studies have shown that the thermal expansion coefficients of these alloys also reveal anomalies.
An explanation is eiven in terms of the electron contribution to the cohesive energy of these systems. SiC whiskers were viewed in axial and radial directions, revealing a high density of stacking faults, voids and other crystal defects. Specimen ti 1ti ng 'experiments were performed in TEr,1, and the di ffraction contrast of the defects were analyzed. The crystal structure of individual whiskers was characterized by a random mixture of hexagonal po1ytypes due to the high fault density. Detailed analyses of the various crystal defects found in SiC whiskers will be presented. Jackson, Systems Research Laboratories, Inc. SSn-SSi alloy aged for 40 hr. Growth of the silicide boundaries then traps the impurities within the silicide producing the morphology observed. Raghavan, R.
Mueller, C. The analysis indicated that two types of carbides can form in the system. One of the carbides was a Ni-Mo rich M6C carbide which had a maximum solubility of 31 at. The other carbide is a Cr rich M23 C6 carbide which has a maximum solubility of 10 at. Data are presented on the lattice parameters for the two phases and relationships are developed between the lattice parameters of the two phasef both for the binary ZrB? Jackson, Systems Research Laboratories Inc.
To reduce this labor a BASIC program useable on an Apple computer has been written by which the analysis for the zone and related planes is accomplished Examples of analysis of diffracton patterns from HCP and tet;agonal systems are presented. Kowbel and W. Brower, Jr. A model of the surface structure and surface composition of Pd 4 Si glassis presented. The theoretical reconstruction of the sur:face was carried out under the assumption that on the clean vacuum atmosphere surfaces the bond lengths between the atoms in the first and second layers are shorter than the bond lengths in the bulk.
Thus, the reconstruction was considered as a function of coordination number. Based upon this surface structural model, surface segregation was predicted for Pd4Si glass. It was found that the lower the coordination of a particular site, the greater the tendency for surface segregation. In the case of Pd4Si the segregation of silicon is taking place preferentially at sites with coordination numbers ranging from 4 to 8. This vacuum model has been extended by considering physical adsorption of helium on a computer simulated Pd4Si glass surface. The distribution of sites on the Pd4Si glassy surface interacting with helium atoms has been calculated and compared to that on the glass-vacuum surface. The adsorbed atoms have the effect of reducing bond contraction.
In both, surface is displayed via VCR tape surface graphics. H:lO a. Liberman, Steel Heddle Mfg. The boundary conditions for calculations within each zone depend on the type of base metal and the phase diagram of the base metal with alloying elements. A computer program has been developed for calculations. Examples of calculated diagrams for some aluminum, magnesium and copper alloys will be discussed. Dalder, S. Benson, B. Box , Lewistown, PA Ultrasonic inspection of thick austenitic stainless-steel welds is often hampered due to problems such as anisotropy of sound-wave velocity, high and variable attenuation of incident and reflected sound waves, and problems of identification and accurate measurement of flaw size.
Therefore, a highly damped, variable focus dual search: receive U. Its application to the detection, location, and identification of such welding reacted defects as slag inclusions, lack of fusion, porosity and weld-metal cracking is described in detail. Use was made of linear, elastic fracture-mechanics LEFM -based fatigue crack growth and fracture codes to determine initial and critical defect sizes for both the Type L weld metal and surrounding Type LN austenitic stainless-steel structures that make up a large ton set of high-field KG superconducting magnets.
Monday, October 3, Canadian Ballroom a. Franklin Plaza Session Chairmen: J. Perepezko; Department of Met. Seydel, NDE Eng. Box , Idaho Falls, ID The aim, in part, is to provide a reliable, real-time, in-situ and nondestructive measurement of skin thickness in the continuous casting of steel, to help prevent breakouts. Lott and P. Box , Idaho Falls, NDE techniques are being developed for fusion zone sensing of arc welding processes for closed-loop process control. The applicability of ultrasonic sensing for real-time seam-tracking and measurement of weld penetration will be discussed. Clough and H. Acoustic emission is a technique well suited for monitoring material melting and solidification by an electron beam, since it provides a real time volumetric survey of the process.
At the same time, heat flow calculations are available which can predict the extent and rate of me 1t i ng and reso 1 i difi cat ion. The one and two dimensional results can include stationary and moving sources and show the effects of alloying. The present paper presents recent results obtained by acoustic emission studies of electron beam melting and solidification, and their relation to the evolution of microstructure during solidification. Specimens were pulsed for approximately ms by the electron beam, and the acoustic emission signal was then followed during solidification. One of the most striking results is the difference in acoustic emission signal level obtained in pure aluminum and Al-Cu alloys.
Relatively small amounts of emission were produced in the pure aluminum, and no cracking was observed in the solidified microstructure. Much larger amounts of AE were produced in the Al-Cu alloys which also exhibited extensive hot cracking. A limited amount of data shows that the energetic acoustic emission of Al-Cu alloys is believed to originate from cracking and special forms of plastic deformation. Coyle, M. Jon, V. Palazzo and D. Cruickshank; Western Electric Co.
Box , Princeton, NJ Acoustic Emission AE and quantitative optical metallography were used to detect and evaluate solidification cracking in several commercial austenitic stainless steels. Cracking was induced by high peak energy, pulsed laser irradiation. A photo detector was used to initiate a pre-set electronic gate incorporated with a delay function to capture the AE information. Four AE zerocrossing counts were obtained by using four thresholds to discriminate different AE amplitudes. These AE zero-crossing counts and AE burst counts were then correlated with the severity of cracking using a statistical method called the discriminant analysis function.
Attempts were made to correlate the AE'data to the size and frequency of the cracks for both single and I1l. Iltiple pulsed exposures. Caines, D. Real materials, such as welds and castings, however, due to heat treatment, may become anisotropic as well as inhomogenous. Iltiple scattering, mode conversion, etc. Some recent theoreti ca 1 and experi mental developments wi 11 be presented, which will include reflection and transmission through An exploratory development program was conducted by NAVSEA to develop methods to determine the quality of welds produced during manual shielded-metal arc welding SMAW of HY steel, through the use of Acoustic Emission AE. Deliberate slag and porosity defects were introduced during welding.
AE Weld Monitor. It was found that the AE Weld Monitor was able to detect deliberate defects during SMAW, but there were a relatively large number of AE flaw indications which were not confirmed by post-weld radiography. Based on these results, a focused effort was initiated to identify reasons for the above results and to establish an improved capability to effectively monitor'the SMAW process. The detailed AE, radiographic, and metallographic analyses wi 11 be reviewed, as wi 11 be the technology gui del i nes developed.
Marzke and William S. ThIS in turn requlres that the overall electronic state of such matter be reasonably well characterized. The difficulties associated with meeting this latter requirement can be illustrated by conSidering an example of an aggregate of small metallic particles. Not only must the delocalized electrons. Experimentally, among the few direct probes available for both interior and surface electronic states of finely divided matter are measurements of electronic and nuclear magnetism.
These measurements also yield some of the short-range structural information needed for environments that lack long-range order. A review will be given of techniques available for magnetic characterization and of the progress of several ongoing investigations. Buxbaum, MatIs. Green, Jr. Above a certain threshold concentration oxygen appears to have a severe embrittling effect on titanium alloys. Variations in the ultrasonic data were correlated with results from quantitative metallographic analysis and hardness testing. Similar data for welded Ti specimens will also be presented. Franklin Plaza Session Chairmen: Prof.
James T. Current VLSI technology has progressed to where typical devices has spatial extents of only 1. Although this size scale is marginally in a region where the semi-classical Boltzmann equation is valid several modifications are required. Especially the environment and replicated device structures can lead to renormalization of the energy spectrum and long-range interactions that modify device performance. Homogeneous clusters are produced in molecular beams at final densities 50 low that they are in the "splendid isolation" which leaves them free of interactions with vents, matrices, surfaces, or each other.
The salient features of cluster production will be outlined. Results of high energy 40 to keV electron diffraction from these beams reveal that as cluster size is reduced, changes such as a decrease in unit cell parameter, a transition from one crystalline structure to another, appearance of a progressively larger fraction of non-crystalline phase, and gradual transition to minimum energy configurations such as icosahedra, are seen. Under some conditions the diffraction patterns are used to estimate cluster size and temperature. Session Chairman: R. Balluffi, Dept. Bristo",e and R. Harrison, Symposium a. De Hosson and F.
George St. Break a. Often it is difficult to obtain a clear representation of the relaxed boundary structure, especially in the case of small atomic displacements. Bristowe, Dept. In particular the dislocation core structure and energy of high-angle twist and tilt boundaries is examined by comparison with recent TEM observations and rotating particle experiments as well as diffraction data and energy measurements. Guillope, V. Molecular statics or quasi dynamic computational procedures provides a usefull way to obtain important results on the structure of grain boundaries during the last years. However, the minimum energy ,onfigurations for grain boundaries obtained by these methods completely ignores temperature etfects.
Davenport and M. Weinert, Dept. TIle systems discussed will include palladium on niobium, cesium on tungsten, and nickel on copper. The calculations were performed with various techniques ranging from model Hamiltonians to complete solutions of the density functional equations. In general it is found that the electronic structure closely resembles the bulk within one or two atomic layers of the interface. Using these methods it is possible to calculate directly the interface energy. Jacucci, A. Perini, 1st. Properties of the interfacial free energy are deduced, the consequences of which on the nucleation rate are discussed.
Franklin Plaza Session Chairman: D. Drawer , San Antonio, TX Vasudevan and P. Bretz, Aluminum Company of America. Al coa Center, pA The influence of microstructural and environmental factors on slow fatigue crack growth behavior is investigated for several ingot and powder metallurgy alloys of the 2XXX and 7XXX series Fatigue crack growth data are interpreted in conjunction with analyses from scanning and transmission electron microscopy, secondary ion mass spectroscopy and X-ray photoelectron spectroscopy. Several concurrent mechanisms involving crack closure, moisture-induced embrittlement effects and intrinsic microstructural influences are examined as functions of alloy composition, aging treatment and process variables in order to gain an insight into the near-threshold fatigue behavior of aluminum alloys.
Suresht and R. The significance of such closure mechanisms is discussed with reference to the mechanical, microstructural and environmental factors which are known to affect near-threshold behavior. Department of Energy under Contract No. A study of crack growth near threshold has been performed on Al alloys -i. Threshold in vacuum depends only upon the intrinsic material characteristics. From these data the more complex behaviour in air is analysed as the combination and the interaction of differents factors, i. BREAK The state of coherency of a crystal interface is a function of the lattice correspondence chosen to relate the two crystals. The relation between types of correspondences is discussed, and the characteristics of coherency. Examples are taken from the results of computer simulations of interfacial structure.
McEvily and K. In contrast to fatigue crack growth in the intermediate range, fatigue crack growth in the near threshold region is known to be more structure-sensitive. For example, the threshold level of steels has been found to vary inversely with grain size, whereas growth in the intermediate range is more a function of modulus. With respect to mechanism associated with the threshold region two features often stand out. One is the tendency for the growth mode to shift from Mode I to Mode II, and the other, not unrelated to the first, is the increase in the ratio. Starke, Jr. However, this ,Tlodel does not account for environmental effects and sl ip modes which can change FCGRts. Threshold and FCGR's have been calculated using the mOdified equation and compared with the experimental data.
The interrelationships between sl ip mode, environment, 51 ip reversibi I ity, crack path morphology, crack closure and the predictive capabilities of the model will be discussed. Bat10n, M. E1 Boujdaini and J. In an attempt to elucidate the exact role played by p1asticityinduced crack closure and crack closure induced by corrosion product wedging during fatigue crack propagation in the threshold region, the values of 6Kth for a-brass and for T3 aluminium alloy were measured at tWb R-ratios 0.
Franklin Plaza Session Chairman: W. Johnson, Dept. Beshers and V. Acoustic harmon1cs, principally the second A2 and third A3 , appeared at the higher amplitudes. A2 was little affected by either deformation or magnetic field. These results show that the mobility of dislocations in Armco iron is strongly enhanced by prestrain. The solute atoms have a difference in size in comparison to the solvent atoms. A net force on a dislocation based on a semi-continuum elastic interaction between the solute atom and an edge dislocation was determined by assuming the contributions from each of the solute atoms in the lattice. A small stress was applied, and the dislocation moved forward, until it reached a static equilibrium point where again the force balance was zero.
If the dislocation stopped, the stress was again incrementally increased. This process was continued until the dislocation had traversed the entire slip plane. The results obtained will be discussed in terms of the size of the slip plane, i. It is found that in some cases that both the applied stress and misfit stress can lead to enhanced stability of the precipitates when morphology changes do not occur e. C,eneralized H k' s Law was used to deri vethe transverse elastic response as a function of loading direction. It is shown that, except for loadings in and , a constant value of Poisson's ratio does not exist.
FOr most loading directions, the transverse elastic responce is anisotropic. Experments perfonned on the superalloy single crystal confirms this anisotropy. A least square fit between the experimental data and the mathematical equation yields the three crystal constants for the superalloy crystal. This provides a novel technique of measuring elastic constants of a cubic crystal. An a. Long range internal stresses due to a polarizable substructure of dislocations, such as subgrain boundaries or network dislocations, are analyzed using a self-consistent continuum model.
The polarization of the substructure is treated as transformable inclusions which are partially constrained by the elastic matrix. Information of both the mean field and the spatial variation of the internal stress can be deduced from the consideration of static equilibrium and interaction energies. The results are in good agreement with the numerical simulation of Gibeling and Nix and with transient creep observations.
The role of internal stresses of this type, in thermal creep and irradiation creep, is discussed. Measurements of the large amplitude internal friction in brass 1 are interpreted by postulating a Rayleigh law of deformation in analogy to Rayleigh's Law in magnetism. As in the case of the plateau stress, the internal friction is due to the interaction between dislocation and solute atom which is taken into account with the help of statistical considerations.
Jon, wop. Beshers f J. Lucas, Sandia National Laboratories, Albuquerque, NM A novel technique for the interpretation and determination of the long range internal stress, ai, by stresss recovery will be discussed. Basically, the stress recovery method is carried out by loading the tensile speLimen to yield, and then rapidly dropping the load to a lower predetermined level. The specimen is then held under a fixed grip condition at a fixed displacement cQrresponding the predetermined load drop; and recovery is qllowed to take place for min. The magnitude of the recovery stress is plotted against the applied stress.
The internal stress can be determined from the recovery va. For metal forming processes, a knowledge of hardening and flow behavior is necessary for the prediction of local plastic instabilities and the development of accurate constitutive relations. Often, metal deformation processes involve multiple stress paths. In addition aluminum sheet has been prestrained by rolling and subsequently tested in tension, compression and plane-strain compression. Department of Energy. Bang and M. Two types of specimens, as-UHV purified and oxygen doped, were examined after tensile deformation at 77 K. Although the dominant slip traces observed belonged to the primary slip planes in both specimens, the strain analysis clearly demonstrated that the co-planar double slip occurred in the purified specimens, while single primary slip occurred in the doped specimens.
The mechanisms of the coplanar double sl ip anomalous slip and the d islocationsolute interaction will be discussed with the observations. This correlation can be modelled with certain simplifying assumptions. Tne rate of microvoid growth may vary with invariant nucleation conditions, or nucleation parameters such as strain or voluli! Better predictive ability requires dtltailed in. Burns and J. Together with the slip force obtained by Rice and Thomson, radial and tangential forces are obtained in simple forms. As expected, the radial force agrees with the general theorem of Asaro, namely this force depends only on the distance from the crack tip, independent of the angular position or the orientation of the slip plane; it is separable into contributions from the component two edge and one screw Burgers vectors.
However, the tangential force depends on both the position of the dislocation and the orientation of the slip plane. It is in a direction that attracts the dislocation towards the crack surfaces. Near the crack surfaces the tangential force agrees with the image force due to a free surface. The angular pOSition at which the tangential force is zero depends on the orientation of the slip plane. Furthermore, the tangential force is not additive with respect to the two edge components of the Elurgers vectPr. The results will be applied to the interaction of a crack with misfit inclusions.
I or Mode III loading. The emission process takes place when the local stress intensity factor reaches a critical value. Then the dislocation moves away with a velocity proportional to the 3rd power of the effective shear stress which is over and above the lattice friction. It is found that the time needed for saturation depends very strongly on lattic;e friction, weakly on the applied stress and is almost independent of the critical stress intensity factor for dislocation emission. The dislocation-free zone increases with the number of dislocations emitted, is larger for larger critical stress intensity factor, but not much affected by lattice friction. The zone size increases upon unloading when some dislocations disappear into the crack.
The dynamic distribution of dislocations is different from the static one, approaches the latter only at saturation. Nanjing, China. Robertson and H. Birnbaum, Dept. The mechanisms of hydrogen embrittlement of Ni were investigated during in-situ deformation and fracture experiments in the Argonne National Laboratory HVEM. The dislocation structure at crack tips formed in vacuum and in H2 gas were examined in detail and the dynamics of fracture studied using high-resolution video recording methods. The fracture was primarily mode I and was generally transgranular. The conclusions of this study support previous work in that hydrogen embrittlement resulted from a decrease in the flow stress due to hydrogen and failure by a locally enhanced plasticity mechanism.
A short video tape of hydrogen embrittlement in the HVEM will be shown and possible mechanisms discussed. Park, A. Thompson and I. Bernstein, Dept. Science, Carnegie-Mellon University, Pittsburgh, PA The effect of internal hydrogen on the substeps of void initiation, growth and coalescence in a spheroidized steel is being studied. Unnotched tensile specimen were tested and analyzed confirming our previous findings that hydrogen did not significantly assist void initiation at carbides and the growth of voids prior to final fracture. Lewandowski, A. Thompson, Dept. Science, Carnegie-Mellon University, Pittsburgh, PA The effects of microstructure and precharged hydrogen on the frac- ture behavior of fully pearlitic steel have been microstructures. Uniaxial studied.
Furthermore, 1n the coarse pearlitic samples, fracture appeared to follow the strain gradient imposed by the notch, consistent with a strain-assisted fracture. Thompsor1, Dept. Initiation loads and origins were obtained using round-notched, four-point bend specimens. The present work has expanded that study to bainite and martensite in a steel. Crack initiation loads and stresses were compared between the microstructures at equal yield strength and at equal toughness.
SEM fractography from four-point bend bars indicated that hydrogen changed the failure mode from MVC to predominantly a ductile-tearing, or TTS, fracture in both microstructures, with some areas of quasi-cleavage evident in martensite. Quantitative x-ray diffraction and transmission electron microscopy were used to characterize the microstructures. Research sponsored by the National Science Foundation. Kim and J. Morris, Jr. Research on hydrogen embrittlement of ferritic Fe-Ni steels was done to increase the understanding of the mechanism of cracking and the influence of microstructure. Specimens embrittled by hydrogen charging were broken and the fracture surfaces were studied by optical, scanning electron, and transmission electron microscopy.
The embrittlement in the research alloys was governed by cracking along the boundaries of martensite laths. NC, NR Hintz, L. Heldt, Dept. Clough, J. Moulder, physical Electronics Div. Scanning Auger electron spectroscopy has been used to, observe the fracture behavior and determine surface chemistries of a number bf oriented nickel bicrystals following several different thermal and hydrogen charging treatments.
The results are briefly discussed in terms of current embrittlement models. This work was supported by the U. U a. Stone, S. Ruoff, J. The carbon activity and microstructure are known to play an important role in the rate of hydrogen attack. We have established a correlation between the microstructural chanQes and the deceleration of the nucleation and growth processes observed over long exposure times. A model has been developed which describes these effects. This model will be di scussed. Session Chairmen: A. Ghosh and C. Kashyap, N. Mukherjee, Dept.
CA There has been Significant advances in elucidating the details of both deformation mechanisms and cavitation phenomenon in superplasticity. However, there are certain problem areas that deserve serious attention. Among these are: Evaluation of parameters of the constitutive relation and their interdeperldence on the test variables, significance of disloc!
Fine grain superplasticity has been most frequently achieved in two-phase materials. The physical origin of this phenomenon is explored from the standpoint of structure, thermodynamics, and kinetics. The formal theory of lattice diffusional creep in twophase materials I-W. Chen, Acta Metall. Furthermore, when deformation is eventually limited by the climb of interface dislocations at small grain size t back stresses due to non-uniform piating give rise to a non-linear stress dependence. Fatigue deformation was studied using 8 TMS Fall Meeting the scanning electron microscope and two stage carbon replicas.
The amount of boundary sliding increased with decreasing strain ra te. I ntergranu 1ar cracks were observed on all s peci mens. The results will be discussed in terms of current models for superplastic deformation with emphasis on the role of grain boundaries in superp1astic deformation. Superplasticity is of considerable commercial interest because of the possibility of utilizing superplastic forming processes. It was considered in early work that the high ductilities associated with superplasticity preclude the formation of cavities.
The characteristics of cavity growth and interlinkage are discussed with reference to recent experimental observations of hole growth during superplastic flow. Wilkinson and C. Macroscopic neck development is largely controlled by the strain hardening produced by strain enhanced grain growth. This has been modelled, and the result is an instability parameter which can be determined from data collected using tensile tests at constant elongation rate.
The cavitation behaviour of this material has also been studied. Damage accumulation is independent of strain rate below the peak in rate sensitivity. Damage develops by the growth and coalescence of cavities, but without the appearance, of any damage instability. Final failure is the result of load shedding to the remaining ligaments, producing accelerated damage in the fracture plane. Caceres, Institute for Materials Research, McMaster University, Hamilton, Ontario LaS 4Mt, Canada For many superplastic alloys, grain growth during superplastic flow far exceeds that which occurs during static annealing at the same temperature. A phenomenological model for the dependence of grain growth on strain rate gives three regimes. At low strainmtes, no enhancement is found, and grain growth occurs at the static annealing rate.
At intermediate strain rates, grain growth is enhanced by grain boundary sliding, such that d "Vs, the sliding rate. At high strain rates, two effects are found. First, the contribution of sliding to creep is diminished. Second, the grain boundary velOCity approaches an upper limit set by the inherent mobility of the unrestricted boundary. The development of the model will be discussed, along with proposed mechanisms for the effect of grain boundary sliding on migration. A comparison of the model with data will also be given. Leighly, Dept. Tortorelli, J. DeVan, and J. Details of the surface and salt analyses will be presented-and correlated with expected corrosion product formation based on known electrochemical behavior.
The results for corrosion in NaN0 3-KN0 3 will be compared to data obtained from a similar type of experiment with type stainless steel exposed to a nitrate-nitrite 49 NaN0 3 KN0 3 -7 NaN0 2 salt. Lower alloy steels such as 2. These results along with the influence of deformation on the structure of the oxide films formed by contact with the molten salt will be discussed.
The stresses on the free surface of the oxide all and 0 22 ' were found! This was attributed to deformation and fracture of oxide layer, thus resulting in stress relaxation. The effect of oxide growth stresses on the oxide scale integrity and on the performance of high temperature materials will be discussed. Shenoy and J. Unnam, Vigyan Research Associates, Inc. With a new thermal protection system, called the metallic mu1tiwall deSign, about a quarter of the shuttle surface area would be covered with titanium. Tota'l oxidation kinetics were determined by thermogravimetric method, oxide thickness was estimated by X-ray diffraction TMS Fall Meeting 9 and microscopy, and oxygen depth profiles were deduced from microhardness measurements on the specimen cross-section.
Based on these data, a model for the oxidation of Ti is proposed. In general, the alloys exhibited twostage oxidations with positive and negative deviations from parabolic behavior. They can be attributed to microchemical and microstructural developments in the scale. Oxidation decreased with increasing alloy Cr-content. On higher Crcontaining alloys, the scale was mainly single-layer consisting of M20 3 rhombohedral oxide. Scale failure oc'curred randomly on the IOwt. This resulted in localized stratified layers similar to that developed on 3wt. Session Chairman: N. Box 70, Albany, Oregon Cline and S. Bhat, Inland Steel Company, East Chi cago, IN As part of a larger program to study the effects of FeO surface layer on fatigue crack initiation, the morphological features and the surface coverage of the oxide have been studi ed in detail.
For short oxidation times « 30 minutes , the oXlde growth was found to be non-homogeneous and the shape of the individual crystals varied from being spherical to irregular. At longer oxidation times, the growth became facetted. Depth profi 1i ng usi ng Auger Spectroscopy i ndi cated c1 early that the oxide was predominantly FeD gO. However, the uneven sputtering of the oxi de and the metal phases di d not permit a quant i tat i ve relationship between the sputtering time and the oxide thickness.
For the experimental conditions used in the present study, the oxidation of iron to wustite appears to be controlled by nuc 1eat i on and growth phenomena. Yang, G. Welsch and T. The spinel NiC containing large amounts of Cr was observed in the inner portion of the oxide scale on implanted alloys. The outer scale consisted of NiO with a large grain size. Porosity was observed on the grain boundaries of the inner oxide and dislocations in the large NiO grains. These observations are compared with unimplanted alloys where the oxide scale is much less adherent. The structures of scales were determined using X-ray diffractometry. Morphological studies of the oxide surface were done using scanning electron microscopy.
Transmission electron microscopy was done with parallel sections as well as transverse sections. Quantitatative analysis was carried out using energy dispersive X-ray analysis. A gravimetric analysis was also carried out to determine the kinetics of oxidation of the alloy. University of Illinois at Urbana-Champaign. The general character of the phase relationships in metal-oxygen Particular attention will then be systems will be reviewed. The use of oxygen activity and oxygen diffusivity data to derive oxygensubstitutional solute interaction energies will be described and illustrated using alloys based on the group V metals V, Nb, h.
Nafziger and N. The resulting phase diagrams, Gibbs energies, enthalpies, and entropies of formation of solid and liquid binary alloys are presented. The effects of nitrogen as an impurity in other alloy systems are briefly discussed. Smith, Dept. Iowa State Univ. For strongly electropositive elements the hydrides are saline, but for most metals hydrogen tends to alloy with metallic electric properties. Hydrogen mobility in such alloys is quite high even at temperatures well below room temperature. Because of large percentage mass differences between H, 0, and T, isotopic effects on physical parameters are frequently measurable. Indeed, in the case of the V-H and V-D systems, even the phase relationships are significantly different.
The hydrogen concentration which can be introduced into a metal at a given temperature is pressure dependent and varies widely from metal to metal. For many metals Sieverts' law is valid at low hydrogen concentrations. A few simple crystal structures occur frequently and systematically in metal-hydrogen systems, but other more complex crystal structures with odd stoichiometries have been reported for some systems in the low tempemture regime.
Extensive thermodynamic and phase data are available. Austin Chang, Dept. All of these phases exist over a large range 'of composition. The manner in which the phase equilibrium relationships in metal-metal binary systems may be modified by the presence of gaseous impurities is at present, although important, largely an unexplored area. Previously detected effects in many alloy systems include the obvious shifting and shape changing of the binary phase diagram boundaries, the stabilization of new alloy phases, and the introduction of new types of phase reactions. In this paper such phenomena are examined, and presented with many examples in a systelll11atic ordering.
Wilcox and B. Chin, Dept. Optical metallographic analysis and precipitation extraction were utilized. The delta morphology changes with time. The type and amount of carbide present changes with austenitizing temperature. Constant austenitizing times revealed no relationship between austenitic grain size and phase transformations but rapid growth occurs with time because of the changing delta morphology. The microstructural observations are briefly related to impact,properties. Fatemi, C. Pande, A. Pattnaik, and B. Ostwald ripening appears to be the dominant growth mechanism for ellipsoidal precipitates, whereas rod-like precipitates follow a complex process which -only at later stages of growth resembles Ostwald ripening.
In this work, the size distribution of ellipsoidal precipitates as a function of time and temperature is examined, showing the agreement between SANS and TEM methods. Zocco and M. It was observed that the aspect ratio of the precipitates remained relatively constant during the coarsening process which indicates that shape coarsening of the precipitates is negligible and size coarsening is the most important process. Particle size distributions, and subsequently average particle size, as a function of time were obtained through the stereo logical measurements outlined by Dehoff for oblate ellipsoids as modified for rod shaped precipitates.
The coarsening kinetics of these precipitates will be discussed in light of recent developments and advances in the theory of precipitate coarsening, and in particular, on the effects of interphase boundary ledge migration as the rate controlling process for coarsening. Rajab, University of Sussex, U. Coarsening consists of two processes, the change of shape towards Funded by U. Department of Energy 8:S0 a. Foulds, GA Technologies Inc. The widths of these zones are related to the base metal preheat temperature and total heat input rate. Microhardness profiles across the zones in the as-welded condition show variations in strength consistent with the changing microstructures. A SEM survey of the microstructure going from weld to base metal revealed four clearly distinguishable microstructural regions: ferrite-martensite at the fusion line, a coarse martensitic structure with little carbide precipitation, a fine martensitic structure with little carbide precipitation, a fine martensitic structure with an increased carbide volume fraction, and a region adjacent to the base metal with feathery areas resembling bainite and a finer distribution of carbides.
These and supplemental TEM observations are discussed- on the basis of expected cooling rates for the different zones. Lippold and B. Odegard, Sandia National Laboratorles, Llvermore, CA The effect of composition on the microstructure and mechanical properties of austenitic stainless steel inertia welds has been investigated. During the inertia welding of Type L the material along the bond line is heated to temperatures slightly below the solidus resulting in a solid-state transformation of austenite to delta ferrite. The amount and morphology of the ferrite is a function of both the composition of the alloy and the location along the bond.
Smooth bar tensile tests of a wide range of Type L compositions revealed that the bond region is stronger than the original base material. The use of notched tensile bars forced failure along the bond line and indicated that the presence of ferrite has little effect on bond integrity. The mechanical properties of hydrogen-charged tensile bars will also be discussed. It was found that despite of precipitate intersections, that gave a sufficient density of growth ledges during precipitation, the coarsening reaction was strongly inhibited and very few precipitates reached their equilibrium shape despite very extensive times of coarsening. The density of intersected precipitates fell more rapidly than did the overall density of precipitates.
The results are in agreement with a ledge growth model. During this period, G-P zones emerge and grow with a time-scaling exponent of approximately 0. The time power law exponent is compared with decomposition kinetics theory predictions. LaSalle, L. Bosworth, Richard J. Braun, Harald E. Brooks, Jennifer E. Brown, M Brown, Marvin L. Burbank, Jane Burdette, Amy M. Burnett, Murray Burnett, W. Burrill, Emily S. Burton, Georganne B. Butcher, Emma Butler, Christopher K. Butler, David Butler, E. A, Buscha C. Caiazza, Amy B. Callwell, Charles E. Caron, Sylvain Carpenter, Charli R. Carpenter, Charlie Carpenter, R.
Charli Carpenter, Robert J. Carroll, Stuart Carruthers, Susan L. Carsten, F. Franci Carsten, F. Chivers, C. Claude, Inis Claude, Inis L. Clothier, William Cloud, John A. Cock, Jacklyn Cockburn, C. Cohen, Stuart Cohen, William B. Conklin, Eileen F. Conkwright, Kathy Conley, Mary A. Connell, Raewyn W. Cook, Lauren M. Cooke, Miariam G. Cooke, Miriam Cooke, Miriam G. Cookson, J. Cookson, John E. Cooper, Helen M. Cooper, Sandi Cooper, Sandi E. Copp, J. Cornell, Kari A. Cosmatos, George P.
Cottam, K. Jean Cottam, Kazimiera J. Cox, Robert W. Cuordileone, K. Dambrogio, Jana Damiano, Sara T. Danforth, Loring M. Davis, Jessica Davis, John T. Davis, Kathy Davis, Lisa E. De Defense. Douglas, R. Drexler, Michael J. Dwyer, Philip Dwyer, Philip G. Eby, Cecil D. Echenberg, Myron J. Edgerton, Robert B. Eisenstein, Zillah Eisenstein, Zillah R. Ellenshaw, Peter Ellert, H.
Ellis, Alfred B. Emmett, Chad F. Evans, R. Evans, Richard J. Farrell, Elaine Farrell, Leslie D. Forrest, A. Forrest, Alan Forrest, Alan I. Forth, Aidan Forth, Christopher E. Y Franke, Katherine M. Furie, Sidney J. Furie, Sidney J Furmanov, Dm. Gagliardo, John G. Bush Presidential Library, George W. Gheith, Jehanne M. Gilbert, Sandra M. Gomaa, Dalia M. Goodman, R. Gordon, Craig A. Gottlieb, Julie V. Gray, Edward G.
Grayzel, Susan R. Greenberg, Karen J. W Griffith, D. Griffith, Jennifer E. Griffith, Kenneth Griffith, Robert K. Groot, Gerard J. Gruber, Aya Gruber, M. Gundersen, Joan R. Gunn, S. Hacker, Barton C. Hagist, Don N. Hall, Richard H. Hammond, Michael Hammons, Crystal B. Hampanda, Karen Hampf, M. Hanson, Anna Hanson, Cindy L. Harari, Yuval N. Harris, Benjamin Harris, C. Harris, C. Harris, Kirsty Harris, M. Hartman, Saidiya Hartman, Saidiya V. Heidler, Jeanne T. Heinecken, Lindy Heineman, Elizabeth D. Heineman, Elizabeth Heineman, Elizabeth D. Higgens, Kathleen J. Higman, B. Higonnet, Margaret R. Higonnet, Patrice L. Hilhorst, Dorothea Hilkhuijsen, Jos W. Hodgson, Godfrey Hodgson, Marion Stegemen. Hoffman, Peter J. Hopkin, David M.
Hopkin, David Hopkins, A. Hosek, Susan D. Ford Hufton, Olwen H. Hughes, Michael J. Hughes, Nick Hughes, Steven C. Hull, Isabel V. Immermann, Richard H. Inglehart, Ronald C. Irvine, Jill A. L, Gradus J. James, Dante James, Leighton S. John, Howard St. John, Lauren St. John, Ronald Bruce St. Johnson, Alan Johnson, David K. Johnson, Edgar M. Johnson, Laurie Johnson, Lyman L. Johnson, Lyman Johnson, Nona J. Jones, Darrell D. Jones, David E. Joseph, C. Jr, Henry Louis Gate Jr. L, Ashcraft K.
Kansteiner, Wulf Kanter, Deborah E. Kaufman, Joyce P. Kay, Rebecca Kaye, Harvey J. Keene, Judith Keene, Michael L. Keep, John L. Kennedy, David Kennedy, David M. Kennett, Lee B. Kennon, Donald R. Kenovic, Ademir Kent, Donald H. M Kersey, Harry A. Khachaturian, E. Klein, Kerwin Klein, Martin A. Kleiner, Harry Kleiner, Samuel M. Lutz P Koepnick, Lutz P. Kramer, Nicole Kramer, Paul A. Kritvus, Ania Kritzman, Lawrence D.
Kuehl, William Kuehnast, Kathleen R. L, Miller L. Landers, Jane Landes, Joan B. Wal Laves, Walter H. Lawrance, Benjamin N. Leatherman, Janie Leatherman, Janie L. Lee, Jonathan L. Lee, Wayne E. Lee, Wayne degree supervisor Leed, Eric J. Leonard, Elizabeth Leonard, Elizabeth D. Leonard, Robert Z. Lethen, Helmut Leuschen, Kathleen T. Levenback, Karen L.
Licata, Salvatore J. Lilly, J. Lipman, Jana K. Little, Ann M. Little, Lester Knox Little, R. Liu, Lydia H. Lubitsch, Ernst Luby, Roy S. MacCurdy, John T. MacKenzie, Megan H. Macpherson, W. Mallett, Robert Mallon, Florencia E. Maloba, Wunyabari Maloba, Wunyabari O. Manegold, Catherine S. Walvin Mangan, J. Manktelow, Emily J. Manley, author Elizabeth Manley, Elizabeth S. Marrs, Cody Marrus, Michael R. Marshall, T. Marshall, Thomas H.
K Matembe, Miria R. Matfess, Hilary Mather, Susan H. Mathers, Jennifer G. McGlynn, Frank Frank S. Mellor, Anne K. Merry, Lois K. Messac, Luke Messerschmidt, James W. Meyer, Alfred Meyer, Guilherme E. Miller, Robert L. Robert Miller, Sally M. Mitchell, Gabby Mitchell, Gabby C. Moeller, Robert Moeller, Robert G. Moeller, Robert G. Moghadam, Valentine M. Mooney, Jadwiga E. Moore, Brenda L. Moore, Brian L.
Moran, Terence P. Morden, Bettie Morden, Bettie J. Moses, A. Moxey, Keith Moya, Jose C. Moyd, Michelle R. Mustillo, Sarah A. Myers, Ramon H. Naimark, Norman M. Naimark, Norman Naimark, Norman M. Nalty, Bernard C. Nash, Gary B..Kelly, Case Study: Resul Rockwell International Corporation of Metallurgical and Mineral Engineering University 01 Theme Of Loss In The Last Leaf - Madison Kinetic modeling of solidification Case Study: Resul Rockwell International Corporation small droplets Case Study: Resul Rockwell International Corporation developed using classical nucleation theory. BoxCase Study: Resul Rockwell International Corporation, MIU. The hydrogen to metal ratio is shown to decrease with increasing electron to atom ratio. What is it changed?.