Factors influencing the strength differential of high strength steels
01 Feb 1972-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science (Springer New York)-Vol. 3, Iss: 2, pp 369-375
TL;DR: In this article, the effect of microstructures on the strength differential (SD) of high-strength steels was analyzed, i.e., the strength level difference between the tensile and compressive flow curves.
Abstract: Room temperature tensile and compressive true stress-true strain curves of various high strength steels (quenched and tempered 4340 steel, 410 martensitic stainless steel, and H-11 steel; and aged 300-grade 18 Ni maraging steel) were analyzed to determine the effect of the various microstructures, on what has been termed the strength differential (SD),i.e., the strength level difference between the tensile and compressive flow curves. Care was taken to insure that the compressive deformation was homogeneous. Regardless of the amount of plastic deformation, the quenched and tempered steels exhibited a higher flow stress in homogeneous compressive deformation than for tensile deformation. The extent of the SD was dependent on tempering temperature. This observation is consistent with what others have observed regarding yield strength behavior of quenched and quenched-and-tempered steels. Despite the low carbon content, aged maraging steel also showed a greater resistance to homogeneous compressive deformation. Metallographic examination of the maraging steel revealed the banding that is indicative of segregation. However, homogenization had little effect on the SD despite a change in austenite grain size, reverted austenite content, and the austenite-to-martensite transformational strains shown by Goldberg to be present in segregated material.
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TL;DR: A survey of the advances in strength theory (yield criteria, failure criterion, etc) of materials (including matellic materials, rock, soil, concrete, ice, iron, polymers, energetic material etc) under complex stress was presented in this paper.
Abstract: It is 100 years since the well-know Mohr-Coulomb strength theory was established in 1900. A considerable amount of theoretical and experimental research on strength theory of materials under complex stress state was done in the 20th Century. This review article presents a survey of the advances in strength theory (yield criteria, failure criterion, etc) of materials (including matellic materials, rock, soil, concrete, ice, iron, polymers, energetic material, etc) under complex stress, discusses the relationship among various criteria, and gives a method of choosing a reasonable failure criterion for applications in research and engineering. Three series of strength theories, the unified yield criterion, the unified strength theory, and others are summarized. This review article contains 1163 references regarding the strength theories. This review also includes a biref discussion of the computational implementation of the strength theories and multi-axial fatigue.
339 citations
TL;DR: In this article, a new model for the source of friction during the steady-state sliding of metals is described, focusing on the plastic work done in the near-surface region, described in terms of work hardening, recovery and the microstructure existing during steady state sliding.
310 citations
TL;DR: In this paper, the authors examined the stress-strain behavior of quenched and tempered AISI 4310 and 4330 steels in tension and compression under superimposed hydrostatic pressures up to 160 ksi (1104 MN/m 2 ).
279 citations
TL;DR: The authors showed that the difference between the tensile and compressive strengths of tempered martensites is primarily a manifestation of the general pressure dependence of flow stress in these materials and that the volume expansion after deformation was much smaller than that predicted by the normality flow rule of plasticity theory for materials with such pressure dependence.
Abstract: Earlier results showed that the difference between the tensile and compressive strengths of tempered martensites is primarily a manifestation of the general pressure dependence of flow stress in these materials. However, the same results also showed that the volume expansion after deformation was much smaller than that predicted by the normality flow rule of plasticity theory for materials with such pressure dependence. Additional results now obtained on maraging and HY-80 steels support these conclusions. The results for all these materials exhibit a strong, but not perfect, correlation between pressure dependence, yield stress, and volume expansion. The volume expansion, however, which is believed to result primarily from the generation of new dislocations, is very small and does not appear to be essential to the pressure dependence. Most of the pressure dependence, the portion responsible for the discrepancy with the normality flow rule, may be an effect on dislocation motion. The results suggest that an appropriate plasticity model would be one in which the octahedral shear yield stress is linearly dependent on the mean pressure, but the volume change is negligible in violation of the normality flow rule. Such a model has been proposed previously for the plastic deformation of soils. However, unlike that model, the present theory includes strain hardening.
230 citations
01 Mar 1973
TL;DR: In this article, the coupled tensile and compressive volume expansion predictions of elementary perfect plasticity and more complex forms of workhardening plasticity theory, including a possible key role of the theoretical strength under triaxial tension, are described briefly and pictorially.
Abstract: Appreciable differences have been reported recently between tensile and compressive yield strengths (SD or strength-differential effect) in martensitic steels and other alloys, as well as in plastics. Data on plastic volume changes are not yet available for the steels, but a volumeexpansion in both tensile and compressive deformation accompanies the SD effect in plastics and in granular media. In this paper, the coupled SD-volume expansion predictions of elementary perfect plasticity and more complex forms of work-hardening plasticity theory, including a possible key role of the theoretical strength under triaxial tension, are described briefly and pictorially. They then are compared with available data to provide some estimates of the likely successes and failures of the approach. An attempt is made to sharpen the distinction between true and apparent SD, and to suggest several critical experiments.
130 citations
References
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Book•
01 Jan 1950
TL;DR: In this paper, the solution of two-dimensional non-steady motion problems in two dimensions is studied. But the solution is not a solution to the problem in three dimensions.
Abstract: 1. Introduction 2. Foundations of the thoery 3. General theorems 4. The solution of plastic-elastic problems I 5. The solution of plastic-elastic problems II 6. Plane plastic strain and the theory of the slip-line field 7. Two-dimensional problems of steady motion 8. Non-steady motion problems of steady motion 9. Non-steady motion problems in two dimensions II 10. Axial symmetry 11. Miscellaneous topics 12. Platic anisotropy
7,810 citations
TL;DR: In this paper, the amount of cold work necessary to saturate a metal rod with latent energy at 15°C was found to be slightly greater than 14 calories per gram, and compression tests revealed the fact that the compressive stress increases with increasing strain until the total applied cold work was equivalent to 15 calorie per gram.
Abstract: Measurements of the latent energy remaining in metal rods after severe twisting are described. Very much more cold work can be done on a metal in torsion than in direct tension. It is found that as the total amount of cold work which has been done on a specimen increases the proportion which is absorbed decreases. Though saturation was not fully reached even with twisted rods, curves representing the experimental results for copper indicate that it would have been reached at a plastic strain very little greater than the strain at fracture. The amount of cold work necessary to saturate copper with latent energy at 15° C. is thus found to be slightly greater than 14 calories per gram. By using compression instead of torsion, it was found possible to do much more cold work on copper than this, and compression tests revealed the fact that the compressive stress increases with increasing strain till the total applied cold work was equivalent to 15 calories per gram. No further rise in compressive stress occurred with further compression even though the specimen was compressed till its height was only 1/53rd of its original height.
881 citations
01 Feb 1972-Metallurgical and Materials Transactions B-process Metallurgy and Materials Processing Science
TL;DR: In this paper, tensile and compressive stress-strain curves were obtained for several types of microstructures in a variety of steels, including Widmanstatten ferrite-pearlite and ultrafine-grained martensite.
Abstract: Tensile and compressive stress-strain curves were obtained for several types of microstructures in a variety of steels. The strength-differential effect, previously found in martensitic structures, was present in lower, intermediate, and upper bainite and in Widmanstatten ferritepearlite as well as in ultrafine-grained martensite. An equiaxed ferrite-pear lite structure showed no strength differential. The strength differential in martensite increased as test temperature was decreased below room temperature. In several series of tests, the same specimen design was used in tension and in compression to eliminate possible strength variations due to variations in specimen preparation. Several theories which have been proposed for the strength-differential effect are discussed with respect to the present results, and it is shown that most of the previous suggestions are invalid.
89 citations
TL;DR: In this paper, an experimental study was made of friction over the interface between a cylindrical specimen and loading platen during plastic compression, and the variations of normal pressure, shear stress, and friction coefficient were determined using a pair of pressure-sensitive pins installed in a platen so that at least one was oblique to the interface.
72 citations
24 Feb 1964
TL;DR: In this article, the effect of temperature on the tensile, compressive, shear, bearing, dynamic modulus, impact, bend, fatigue, creep, and rupture properties of the 18 per cent nickel maraging steels is investigated.
Abstract: : Since the combination of tensile properties and toughness that can be obtained with the maraging steels is higher than can be achieved with other steels by simple heat treatments, there is considerable interest in using the maraging steels for critical components such as rocket motor cases, pressure vessels, and aircraft forgings. This report includes information on the tensile, compressive, shear, bearing, dynamic modulus, impact, bend, fatigue, creep, and rupture properties of the 18 per cent nickel maraging steels and on the effect of temperature on these properties. Data for the properties of sheet, bar, and forgings, as well as data illustrating the effect of cold rolling, variation in the heat treatment, and elevated-temperature exposure also are presented. Data on the effect of specimen orientation, which are also included, indicate that the ductility and toughness of specimens designed to evaluate the properties in the short transverse direction are somewhat lower than in the other directions. The high strength and toughness that can be obtained in the 18 per cent nickel maraging steels make them attractive for certain critical applications that require these properties. The fabrication characteristics, weldability, and simple heat treatment are other advantages of these steels.
10 citations