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首页> 外文学位 >Experimental Characterization and Modeling of Multiaxial Plasticity Behavior of Austenitic Stainless Steel 304L Produced by Additive Manufacturing
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Experimental Characterization and Modeling of Multiaxial Plasticity Behavior of Austenitic Stainless Steel 304L Produced by Additive Manufacturing

机译：增材制造奥氏体304L不锈钢多轴塑性行为的实验表征与建模

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摘要

In additive manufacturing of metallic alloys, near-net shape 3D components are built in a layer-by-layer fashion. Austenitic stainless steels have high strength and ductility, as they tend to undergo a strain-induced martensitic phase transformation with plastic deformation. The thesis focuses on quantifying process-microstructure-multiaxial mechanical property relationships in additively manufactured 304L austenitic stainless steel (SS304L) and developing a physically-based plasticity model for this material that relates microstructural phase transformation to macroscopic mechanical properties.;The effect of processing parameters on microstructure and mechanical properties was studied using pure SS304L walls. A grain growth model was used to describe austenite grain size as a function of processing parameters and location. A Hall-Petch relationship was used to explain the effect of austenite grain size and morphology on yield strength.;The effects of chemistry, stress state, and texture on martensitic phase transformation were investigated using walls made using a mixture of SS304L powder and iron powder. As the concentration of elements that increase the stacking fault energy of austenite decreased, the austenite stability decreased, and the propensity for martensitic transformation increased.;Multiaxial mechanical tests, including uniaxial tension, uniaxial compression, pure shear, and combined tension and shear, were performed on the material. As the primary texture resulted in a higher driving force for martensitic transformation under uniaxial compression than uniaxial tension, the rate of phase transformation was higher under uniaxial compression, which contradicted the trend in texture-free materials.;A macroscopic plasticity model is proposed to describe the multiaxial plasticity behavior for the material. This model makes use of a chemistry-, stress state-, and texture-dependent martensitic transformation kinetics equation to incorporate the effect of martensitic transformation on mechanical properties. The plasticity model was implemented into a finite element code, and calibrated and validated using experimental data. The good agreement between simulation and experimental results under the stress states studied indicates the model is able to describe and predict the multiaxial mechanical behavior of additively manufactured SS304L. The results in this thesis work enable the use of additively manufactured stainless steels in structural applications, as it provides quantitative links among processing, structure, and mechanical behavior.
机译：在金属合金的增材制造中，以逐层方式构建近最终形状的3D组件。奥氏体不锈钢具有高强度和延展性，因为它们易于经历应变诱发的马氏体相变并发生塑性变形。本文着重于量化增材制造的304L奥氏体不锈钢（SS304L）中的过程-微观结构-多轴力学性能关系，并为该材料建立基于物理的可塑性模型，该模型将微观结构相变与宏观力学性能相关联。使用纯SS304L壁对微观结构和力学性能进行了研究。晶粒长大模型用于描述奥氏体晶粒尺寸与加工参数和位置的关系。用Hall-Petch关系来解释奥氏体晶粒尺寸和形貌对屈服强度的影响。;使用SS304L粉末和铁粉混合物制成的壁，研究化学，应力状态和织构对马氏体相变的影响。 。随着增加奥氏体堆垛层错能的元素浓度的降低，奥氏体稳定性降低，马氏体相变的倾向增加。进行多轴力学试验，包括单轴拉伸，单轴压缩，纯剪切以及组合的拉伸和剪切在材料上执行。由于原始织构导致单轴压缩时马氏体相变的驱动力高于单轴拉伸，因此单轴压缩时相变速率更高，这与无织构材料的发展趋势相矛盾。;提出了宏观可塑性模型来描述材料的多轴可塑性行为。该模型利用化学，应力状态和与纹理有关的马氏体转变动力学方程，将马氏体转变对机械性能的影响纳入其中。将可塑性模型实现为有限元代码，并使用实验数据进行校准和验证。在研究的应力状态下，仿真结果与实验结果之间的良好一致性表明该模型能够描述和预测增材制造的SS304L的多轴力学行为。本论文工作的结果使得能够在结构应用中使用增材制造的不锈钢，因为它提供了加工，结构和机械行为之间的定量联系。

著录项

  • 作者

    Wang, Zhuqing.;

  • 作者单位

    The Pennsylvania State University.;

  • 授予单位 The Pennsylvania State University.;
  • 学科 Materials science.
  • 学位 Ph.D.
  • 年度 2018
  • 页码 156 p.
  • 总页数 156
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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