Topic
Hardening (metallurgy)
About: Hardening (metallurgy) is a research topic. Over the lifetime, 25584 publications have been published within this topic receiving 376012 citations.
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30 Oct 2012-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this article, the effects of Ti addition on the microstructures and mechanical properties of multiprincipal component CoCrFeNiTi x ( x values in molar ratio, x = 0, 0.3, and 0.5) alloys were investigated.
Abstract: The purpose of this study is to investigate the effects of Ti addition on the microstructures and mechanical properties of multiprincipal component CoCrFeNiTi x ( x values in molar ratio, x =0, 0.3, and 0.5) alloys. The CoCrFeNi quaternary alloy displayed a crystalline structure constructed by a simple face-centered cubic solid solution, whereas a plate-like structure consisting of a mixture of (Ni, Ti)-rich R phase and (Cr, Fe)-rich σ phase was observed within the face-centered cubic matrix of a CoCrFeNiTi 0.3 alloy. In a CoCrFeNiTi 0.5 alloy, an face-centered cubic matrix, a (Ti, Co)-rich Laves phase, and R+σ mixed phases were discovered. The compressive strength of the alloys rose by approximately 75% after the addition of Ti. Alloys with high levels of Ti content had high yield stress values and low ductility values. The solid-solution strengthening of the face-centered cubic matrix and the secondary-phase hardening were the two main factors that strengthened the alloy. The CoCrFeNiTi 0.3 alloy exhibited a compressive strength of 1529 MPa and a fracture strain of 0.60; this indicates that this material shows potential for the development of a ductile, high-strength alloy.
253 citations
TL;DR: In this paper, the authors give the most realistic description of the concept of intracrystalline latent hardening through the analysis, at the microstructural scale of the dislocation densities, of various and complementary experimental data, and underline the excessive restriction introduced by the classical assumption of pure strain hardening in the determination of the most general single crystal hardening variation law for a wider range of loading processes.
253 citations
TL;DR: In this paper, a ductile high-entropy alloy of Al0.5CoCrCuFeNi was used for both hot forging and cold rolling, and it was fully annealed in 5h at 900°C, revealing its significantly higher resistances to static anneal softening.
251 citations
31 May 1999-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the AISI 304 was shot peened or deep rolled with different peening intensities, and rolling pressures, respectively, and the resulting near surface properties were characterized by cross sectioning transmission electron microscopy (TEM), residual stress and phase analysis as well as interference line halfwidth and microhardness measurements.
Abstract: Cylindrical specimens of the austenitic stainless steel AISI 304 were shot peened or deep rolled with different peening intensities, and rolling pressures, respectively. The resulting near surface properties were characterized by cross sectioning transmission electron microscopy (TEM), residual stress and phase analysis as well as interference line half-width and microhardness measurements. Cyclic deformation curves were obtained by hysteresis measurements under stress control with zero mean stress. The microstructural alterations in the fatigued surface regions were again characterized by the above mentioned methods. The investigations revealed that both shot peening and deep rolling lead to a complex near surface microstructure, consisting of nanocrystalline regions, deformation bands and strain induced martensitic twin lamellae with high dislocation densities in the austenitic matrix. These microstructural changes severely influence the cyclic deformation behaviour: Plastic strain amplitudes and cyclic creep were drastically decreased by shot peening and especially by deep rolling. Both surface finishing methods were found to decrease crack initiation and propagation rate. Remarkably, the initial residual stress profile and surface strain hardening were not completely eliminated even by applying high cyclic stress amplitudes. This is due to the fact that during cyclic loading dislocation cell structures were only formed in greater depths whereas the nanocrystalline layer remained stable. In the case of deep rolled surfaces, the martensitic layer was even increased by fatigue-induced martensite formation.
251 citations
TL;DR: In this article, the deformation behavior of a superplastic Ti-6A1-4V alloy at 927°C has been characterized by means of constant strain-rate tensile tests up to large plastic strain.
Abstract: The deformation behavior of a superplastic Ti-6A1-4V alloy at 927°C has been characterized by means of constant strain-rate tensile tests up to large plastic strain. Significant hardening has been recorded in the course of deformation. Microstructural studies on deformed samples indicate the occurrence of simultaneous strain-rate induced grain growth, which explains nearly all of the hardening. A small amount of hardening may also be expected from grain elongation or grain clustering effects. As a result of concurrent grain growth, the strain-rate sensitivity is found to decrease with strain, thus indicating that stress-strain rate behavior determined initially may not be applicable after large amounts of plastic strain. The stressJstrain-rate data obtained from step strain-rate test for a variety of grain sizes, together with the grain growth kinetics plots, provide a means for developing a constitutive description for this material at large strains.
250 citations