Effect of retained austenite on subsequent thermal processing and resultant mechanical properties of selective laser melted 17-4 PH stainless steel
Effect of retained austenite on subsequent thermal processing and resultant mechanical properties of selective laser melted 17-4 PH stainless steel
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DOI：
10.1016/j.matdes.2015.05.026
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发表时间：
2015-09-15
影响因子：
8.4
通讯作者：
Kobayashi, Hidetoshi
中科院分区：
文献类型：
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作者：
LeBrun, Tyler;Nakamoto, Takayuki;Kobayashi, Hidetoshi
介绍了用选择性激光熔化法制备的17-4 PH块材拉伸试样的热处理和力学性能。在样品评估之前，进行了各种行业标准和非标准热处理。该热处理的重点是评估老化对机械性能的影响，无论是否事先进行固溶热处理。亚稳奥氏体的体积分数随热处理和开始时效的初始条件而变化。经固溶热处理后的材料由完全马氏体组织转变为体积分数高达20.4%的奥氏体。然而，在峰时效热处理后，SLM材料中残余奥氏体的初始浓度增加，但随着温度的升高和过时效热处理而降低。在拉伸试验中，含有大量奥氏体的试样表现出应力诱导向马氏体的转变。这种行为反映在屈服强度大幅降低，在更大的应变范围内增加加工硬化率，以及延迟局部塑性变形的发生。达到峰值时效状态的各种试样的极限抗拉强度相似，但在达到该强度的应变水平上差异很大。(C) 2015 Elsevier Ltd.版权所有。
Thermal processing and mechanical characterization of tensile specimens fabricated from bulk 17-4 PH material produced by selective laser melting (SLM) is presented. Prior to specimen evaluation, various industry standard and non-standard heat treatments were performed. The focus of this thermal processing was to evaluate the effect of aging on mechanical performance with or without a prior solution heat treatment. Volumetric fraction of metastable austenite was measured to vary with heat treatments performed and the initial conditions from which aging was initiated. Material aged following a solution heat treatment was found to have an austenite reversion from a fully martensitic structure to volumetric fractions as high as 20.4%. Whereas, initial concentrations of retained austenite in SLM as-fabricated material increased following a peak-age heat treatment, but decreased with higher temperature, overaged heat treatments. Specimens with large amounts of austenite demonstrated stress-induced transformation to martensite during tensile testing. This behavior was reflected in substantially reduced yield strengths, increased work hardening rates across greater ranges of strain, and delayed onset of localized plastic deformation. Ultimate tensile strengths for varieties of specimens aged to the peak-aged condition were similar, but differed greatly at strain levels where this strength was achieved. (C) 2015 Elsevier Ltd. All rights reserved.