Phase-field modelling of martensitic transformation in low alloyed steel considering the effect of large elasto-plastic deformation

考虑大弹塑性变形影响的低合金钢马氏体相变相场建模

• 批准号: 452543515
• 负责人: Dr. Oleg Shchyglo
• 金额: --
• 依托单位: Interdisciplinary Centre for Advanced Materials Simulations
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/452543515?language=en
• 关键词: Phase; field; modelling; martensitic; transformation

Martensitic steel is characterized by its ultra-high strength, finding its application in automotive, aerospace, power and other industries. Despite its wide technical importance, theoretical understanding of martensitic transformation kinetics is limited till today. This is mainly due to the extremely rapid transformation kinetics, which makes experimental observation almost impossible, and due to the complex symmetry operations active at the atomic level. Only a set of classical examples, in particular in shape memory alloys with low transformation strains, can be considered as well understood today.The phase-field method is a promising tool for unravelling mechanisms of microstructure evolution in general. Coupled to the state of the art crystal plasticity models, it allows taking into account all relevant mechanisms of martensitic transformation in steels, and investigating their influence on the microstructure formation and mechanical properties. In this project, a three-dimensional phase-field study of martensitic transformation in low-carbon steel is proposed. The full transformation strains of up to 20% are considered for a set of 24 martensite symmetry variants with Kurdjumov-Sachs orientation relationship. We aim to revealing the mechanisms responsible for the formation of the complex, hierarchical lath-martensite microstructure. The focus lies on three major mechanisms, namely the effect of autocatalytic martensite nucleation on the resulting microstructure, the effect of plastic relaxation on the martensite start and finish temperature and its effect on mechanical properties after complete transformation. This study will provide new insight into the kinetics of martensitic transformation and explain the formation of lath martensite microstructure by allowing to individually consider the influence of various material and process parameters, ranging from cooling rate through the elasticity parameters dependence on the alloys composition to the effect of plasticity in austenite and martensite.

马氏体钢以其超高强度为特点，在汽车、航空航天、电力等行业得到广泛应用。尽管马氏体相变动力学具有广泛的技术重要性，但直到今天，对马氏体相变动力学的理论理解仍然有限。这主要是由于极其快速的转变动力学，这使得实验观察几乎是不可能的，并且由于在原子水平上活跃的复杂对称操作。只有一组经典的例子，特别是在形状记忆合金与低的相变应变，可以被认为是今天很好地理解相场方法是一个有前途的工具，解开微观结构演变的机制一般。结合最先进的晶体塑性模型，它允许考虑钢中马氏体相变的所有相关机制，并研究它们对微观结构形成和机械性能的影响。本计画提出以三维相场法研究低碳钢之马氏体相变。高达20%的全相变应变被认为是一组24个马氏体对称变体与Kurdjumov-Sachs取向关系。我们的目标是揭示负责形成的复杂的，分级板条马氏体显微组织的机制。重点在于三个主要的机制，即自催化马氏体形核对所得的显微组织的影响，对马氏体开始和结束温度的塑性弛豫的影响，其对完全转变后的机械性能的影响。这项研究将提供新的洞察力马氏体相变的动力学和解释板条马氏体微观结构的形成，允许单独考虑各种材料和工艺参数的影响，从冷却速率通过弹性参数依赖于合金组合物的奥氏体和马氏体的塑性的影响。