Abstract This work focuses on the experimental investigation into the heat-treatment influence on the plastic flow behavior of the laser metal deposited (LMD) Nickel-base superalloy Inconel 718 and the microstructural based constitutive modeling. The uniaxial compressive mechanical response of the LMD Inconel 718 superalloy was tested over wide ranges of temperature (298–1273 K) and strain rate (500 - ~12000/s). The tested samples were in three different heat-treatment conditions: as-deposited, direct-aged and aged after homogenization & solution (referred to as homogenized STA). Experimental results show that the differences of plastic flow behavior among these three samples were reflected in the amplitude of flow stress, strain hardening exponent, and the dependence on the temperature and strain rate. Based on micro observation, these differences were attributed to the evolution of grain geometry and volume fraction and size of γ" precipitates during heat treatments. A microstructural based constitutive model was developed. The thermal activated interaction between the moving dislocations and the precipitates was firstly proposed and embedded into the constitutive law. The influence of the heat treatments on the dynamic strain aging effect was attributed to the transition of interaction mechanism between dislocations and precipitates with the increasing precipitate size. This model was proved to be able to reproduce the plastic flow response of the LMD Inconel 718 alloy in different heat-treatment conditions over wide ranges of temperature and strain rate.

中文翻译：

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热处理对激光沉积 Inconel 718 塑性流动的影响：基于测试和微观结构的本构建模

摘要 这项工作的重点是热处理对激光金属沉积 (LMD) 镍基高温合金 Inconel 718 塑性流动行为的影响以及基于显微结构的本构建模的实验研究。LMD Inconel 718 高温合金的单轴压缩机械响应在很宽的温度范围 (298–1273 K) 和应变速率 (500 - ~12000/s) 内进行了测试。测试样品处于三种不同的热处理条件：沉积态、直接时效和均质和溶液后时效（称为均质 STA）。实验结果表明，这三个样品之间塑性流动行为的差异体现在流动应力的幅值、应变硬化指数以及对温度和应变速率的依赖性上。根据微观观察，在热处理过程中沉淀。开发了基于微观结构的本构模型。移动位错与析出物之间的热激活相互作用首先被提出并嵌入到本构律中。热处理对动态应变时效效应的影响归因于位错和析出物之间的相互作用机制随着析出物尺寸的增加而转变。事实证明，该模型能够再现 LMD Inconel 718 合金在不同热处理条件下、广泛的温度和应变速率范围内的塑性流动响应。在热处理过程中沉淀。开发了基于微观结构的本构模型。移动位错与析出物之间的热激活相互作用首先被提出并嵌入到本构律中。热处理对动态应变时效效应的影响归因于位错和析出物之间的相互作用机制随着析出物尺寸的增加而转变。事实证明，该模型能够再现 LMD Inconel 718 合金在不同热处理条件下、广泛的温度和应变速率范围内的塑性流动响应。移动位错与析出物之间的热激活相互作用首先被提出并嵌入到本构律中。热处理对动态应变时效效应的影响归因于位错和析出物之间的相互作用机制随着析出物尺寸的增加而转变。事实证明，该模型能够再现 LMD Inconel 718 合金在不同热处理条件下、不同温度和应变速率范围内的塑性流动响应。移动位错与析出物之间的热激活相互作用首先被提出并嵌入到本构律中。热处理对动态应变时效效应的影响归因于位错和析出物之间的相互作用机制随着析出物尺寸的增加而转变。事实证明，该模型能够再现 LMD Inconel 718 合金在不同热处理条件下、广泛的温度和应变速率范围内的塑性流动响应。