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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18 Mar 2019-Materials Science and Engineering A-structural Materials Properties Microstructure and Processing
TL;DR: In this paper, the effects of solution temperature, time and cooling rate as well as aging hardening on the microstructure and mechanical properties of Inconel 718 (IN718) samples have been produced by selective laser melting (SLM).
Abstract: Inconel 718 (IN718) samples have been produced by selective laser melting (SLM). The effects of solution temperature, time and cooling rate as well as aging hardening on the microstructure and mechanical properties of SLMed IN718 have been studied. It is found that the as-fabricated IN718 is characterized with fine cellular dendrites with Laves phase precipitating in the subgrain boundaries, which is profoundly different from cast and wrought materials and needs different heat treatment schedules. The relationship between the minimum solution time and solution temperature is established and it provides a basis for the selection of solution treatment parameters. In addition, decreasing the cooling rate of solution treatment will contribute to the precipitation of strengthening phases. The precipitation temperatures of γ′ and γ″ are about the same for SLMed and wrought IN718, but the former has a faster aging response. The tensile properties of SLMed IN718 can be tuned in a large range by properly varying the microstructure. The highest elongation of 39.1% can be obtained after solution treatment (water quenching) without aging treatment and the highest yield and tensile strength (1374/1545 MPa) can be obtained after the direct aging treatment. The match of strength and ductility is able to be tailored by controlling the amount of strengthening phases, which can be realized by adjusting the cooling rate of solution treatment and aging time.
133 citations
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TL;DR: In this paper, an alternative method to identify the post-necking hardening behavior of sheet metal without using a finite element model is presented, where the key point is the minimization of the discrepancy between the internal and external work in the necking zone during a tensile test.
132 citations
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TL;DR: The results suggest that the cross-protection effect is at least partly due to Hsp70 expression induced by cold exposure, which is lower in the lines selected for resistance to cold than in the controls.
132 citations
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TL;DR: In this paper, the form of the equilibrium phase diagram was determined to obtain information on the age hardening of chill cast alloys with up to 8.75wt% Sc alloy.
Abstract: Aluminium-rich alloys from the Al-Sc system were examined to determine the form of the equilibrium phase diagram and to obtain information on age hardening of chill cast alloys. Samples containing up to 8.75wt% Sc were examined using thermal analysis and optical microscopy. This work indicated a eutectic type of phase diagram with a eutectic temperature of about 665° C and a eutectic composition of about 0.6wt% Sc. The scandium-rich primary phase was found to be ScAl3 which is f c c with a lattice parameter of 0.4105nm. Chill cast samples of a 1 wt% Sc alloy were examined for their age hardening behaviour over the temperature range of 225 to 360° C. A maximum hardness of 77 VHN was obtained after ageing at 250° C for 3 days. This hardness was retained after ageing for a total of at least 12 days. The hardening precipitates were ScAl3 which were observed to form via a discontinuous precipitation mechanism. The ScAl3 precipitates were observed to have a parallel orientation relationship with the matrix.
132 citations
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TL;DR: In this paper, a simple non-linear kinematic hardening law is described which is capable of predicting the response of rail steel to sliding contact loading, and an approximate technique is used to calculate the plastic flow that occurs when the shakedown limit is exceeded.
132 citations