Journal ArticleDOI
On the Hall-Petch relationship and substructural evolution in type 316L stainless steel
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In this article, tensile specimens of Type 316L stainless steel having grain sizes in the range 3.1-86.7 μm were deformed to 34% strain at temperatures 24, 400 and 700°C and strain rate 1 × 10−4s−1 to investigate the Hall-Petch (H-P) relationship, the nature of stress-strain curves and the substructure development.Abstract:
Tensile specimens of Type 316L stainless steel having grain sizes in the range 3.1–86.7 μm were deformed to 34% strain at temperatures 24, 400 and 700°C and strain rate 1 × 10−4s−1 to investigate the Hall-Petch (H-P) relationship, the nature of stress-strain curves and the substructure development. Upto ∼5% strain the H-P relationship exhibits bi-linearity whereas the single Hall-Petch relation is exhibited at larger strains. The presence of bi-linearity is explained by the back stress associated with the difference in the dislocation densities in the vicinity of grain boundary and in the grain interior. The log stress (σ)-log strain (e) plots depict three regimes and follow the relationship σ = Ken in each regime, but with varying magnitudes of the strength coefficient (K) and strain-hardening exponent (n).read more
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Recent developments in stainless steels
Abstract: This article presents an overview of the developments in stainless steels made since the 1990s. Some of the new applications that involve the use of stainless steel are also introduced. A brief introduction to the various classes of stainless steels, their precipitate phases and the status quo of their production around the globe is given first. The advances in a variety of subject areas that have been made recently will then be presented. These recent advances include (1) new findings on the various precipitate phases (the new J phase, new orientation relationships, new phase diagram for the Fe–Cr system, etc.); (2) new suggestions for the prevention/mitigation of the different problems and new methods for their detection/measurement and (3) new techniques for surface/bulk property enhancement (such as laser shot peening, grain boundary engineering and grain refinement). Recent developments in topics like phase prediction, stacking fault energy, superplasticity, metadynamic recrystallisation and the calculation of mechanical properties are introduced, too. In the end of this article, several new applications that involve the use of stainless steels are presented. Some of these are the use of austenitic stainless steels for signature authentication (magnetic recording), the utilisation of the cryogenic magnetic transition of the sigma phase for hot spot detection (the Sigmaplugs), the new Pt-enhanced radiopaque stainless steel (PERSS) coronary stents and stainless steel stents that may be used for magnetic drug targeting. Besides recent developments in conventional stainless steels, those in the high-nitrogen, low-Ni (or Ni-free) varieties are also introduced. These recent developments include new methods for attaining very high nitrogen contents, new guidelines for alloy design, the merits/demerits associated with high nitrogen contents, etc.
Journal ArticleDOI
Additively manufactured hierarchical stainless steels with high strength and ductility
Y. Morris Wang,Thomas Voisin,Joseph T. McKeown,Jianchao Ye,Nicholas P. Calta,Zan Li,Zhi Zeng,Yin Zhang,Wen Chen,Tien T. Roehling,Ryan T. Ott,Melissa K. Santala,Philip J. Depond,Manyalibo J. Matthews,Alex V. Hamza,Ting Zhu +15 more
TL;DR: The potential of additive manufacturing to create alloys with unique microstructures and high performance for structural applications is demonstrated, with austenitic 316L stainless steels additively manufactured via a laser powder-bed-fusion technique exhibiting a combination of yield strength and tensile ductility that surpasses that of conventional 316L steels.
Journal ArticleDOI
Transition of tensile deformation behaviors in ultrafine-grained aluminum
C.Y. Yu,P.W. Kao,C.P. Chang +2 more
TL;DR: In this paper, a model was proposed to explain the deformation behaviors in ultrafine-grained (UFG) aluminum, which showed an evident transition of tensile deformation behavior appeared in commercial purity aluminum as the grain size reduced from micrometer to submicrometer range.
Journal ArticleDOI
Tensile properties of a nanocrystalline 316L austenitic stainless steel
TL;DR: In this article, a nanocrystalline 316L austenitic stainless steel sample (mean grain size similar to 40 nm) was prepared by means of surface mechanical attrition treatment, which exhibited an extremely high yield strength up to 1450 MPa, which still follows the Hall-Petch relation extrapolated from the coarse-grained material.
Journal ArticleDOI
Strength and ductility of 316L austenitic stainless steel strengthened by nano-scale twin bundles
TL;DR: In this paper, a bulk nanostructured 316L austenitic stainless steel consisting of nano-sized grains embedded with bundles of nanometer-thick deformation twins was synthesized.
References
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Journal ArticleDOI
The deformation of plastically non-homogeneous materials
TL;DR: The geometrically necessary dislocations as discussed by the authors were introduced to distinguish them from the statistically storages in pure crystals during straining and are responsible for the normal 3-stage hardening.
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Dislocation Cell Formation in Metals
TL;DR: In this article, it is shown that an array of dislocations, modelled by parallel screw dislocation, of uniform density, is unstable, and that the instability grows ultimately into a dislocation cell structure and the cell size is given by the dominant wavelength of the density modulation.
Journal ArticleDOI
The dependence of polycrystal work hardening on grain size
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Journal ArticleDOI
Influence of grain size on the mechanical behaviour of some high strength materials
Alain Lasalmonie,J. L. Strudel +1 more
TL;DR: In this article, the influence of grain size in complex alloys by incorporating the Hall-Petch stress as one component of the internal stress helps in rationalizing the existence of an optimal grain size where creep resistance is maximized.
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The Strain and Grain Size Dependence of the Flow Stress of Copper
Niels Hansen,B. Ralph +1 more
TL;DR: In this paper, the authors presented tensile stress strain data for 99.999% copper at room and liquid nitrogen temperature as a function of grain size with some microstructural observations made by transmission electron microscopy.