Thermomechanical Treatment of High-alloyed Martensitic Stainless Steels for Complex Parts

复杂零件用高合金马氏体不锈钢的形变热处理

基本信息

批准号：
334485458
负责人：
Professor Dr.-Ing. Thomas Lampke
金额：
--
依托单位：
Professur Werkstoff- und Oberflächentechnik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2017
资助国家：
德国
起止时间：
2016-12-31 至 2019-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/334485458?language=en
关键词：
Thermomechanical Treatment alloyed Martensitic Stainless

项目摘要

In addition to their corrosion resistance, high alloy martensitic stainless steels are characterized by a high hardness and strength. The manufacturing of component parts made of these steels is mainly performed by cold forming of the steel in soft-annealed condition. Only after forming, the material is quenched and tempered to adjust the desired final mechanical properties. However, using cold forming, the maximum achievable degree of forming is often not high enough to manufacture parts with complex geometries. This limitation can be overcome by a thermomechanical treatment (TMT), i.e. a hot forming process with an accurate control of forming and temperature regime. The TMT poses technological and material-scientific challenges for the user, since various physical metallurgical phenomena (e.g. phase transformation, recrystallization or formation of chromium carbides) are activated, which have a strong impact on the formability and the resulting mechanical properties (hardness, strength, corrosion resistance). Yet these effects for the martensitic stainless steels have not been investigated sufficiently.In this project, the effect of TMT processing parameters (austenitizing temperature, holding time, degree and temperature of deformation and strain rate) on the formability as well as mechanical and corrosive properties of these steels will be investigated systematically. One aim is to determine basic requirements for a stable TMT process. Furthermore, physical metallurgical phenomena and the microstructural changes activated during TMT, as well as their influence on the kinetics of precipitation and phase transformation, have to be identified. In the work plan, Continuous Cooling Transformation (CCT) diagrams considering the influence of hot prestrains (DCCT) and austenitizing temperature (TTA) will be determined by dilatometry, metallography and instrumented hardness testing. Moreover, the resulting microstructures will be characterized by optical as well as electron microscopy. The experimental program is complemented by thermodynamic calculations. Formability will be evaluated by hot flow curves, the performance of cupping and deep drawing tests as well as the determination of Flow Limit Diagrams (FLD). Hardness measurements and tensile tests will be carried out to characterize the resulting properties. The corrosion behavior will be evaluated on the basis of potentiodynamic polarization testing. With the aid of statistical design of experiments, the experimental program will be defined and the relationships between process parameters and final properties will be identified. On this basis, phenomenological models will be created to be used in a multivariable optimization to define process windows for the TMT in order to develop specific mechanical and anticorrosive properties. The framework of this research project aims on the establishment of stable TMT processes that lead to an enhanced applicability of martensitic stainless steels.

除了耐腐蚀性外，高合金马氏体不锈钢还具有高硬度和强度的特征。这些钢制成的组件零件的制造主要是通过钢制的钢制冷水状态冷的。只有在形成后，材料才会淬火并进行调节以调节所需的最终机械性能。但是，使用冷形成，最大可实现的形成程度通常不足以制造具有复杂几何形状的零件。可以通过热机械处理（TMT）来克服这种局限性，即具有准确控制形成和温度状态的热形成过程。由于激活了各种物理冶金现象（例如相变，重结晶或形成碳化物的形成），因此TMT对用户构成了技术和材料科学的挑战，这对形成性和产生的机械性能（硬度，强度，强度，耐腐蚀性）具有很大的影响。然而，这些对马氏体不锈钢的影响尚未得到充分研究。在该项目中，将系统地研究TMT加工参数（奥斯丁化温度，固定时间，变形和应变速率的程度和温度）对这些钢的机械性和腐蚀性的影响。一个目的是确定稳定TMT流程的基本要求。此外，必须鉴定出物理冶金现象和在TMT期间激活的微观结构变化，以及它们对降水和相变动力学的影响。在工作计划中，考虑热疗法（DCCT）和奥斯丁化温度（TTA）的影响，连续冷却转化（CCT）图将通过扩张测定法，金理图和仪器硬度测试确定。此外，所产生的显微结构将以光学和电子显微镜为特征。实验程序由热力学计算补充。将通过热流曲线，拔罐和深度绘图测试的性能以及流量限制图（FLD）的确定来评估。将进行硬度测量和拉伸测试，以表征所得的特性。腐蚀行为将根据电位动力学极化测试评估。借助实验的统计设计，将定义实验程序，并确定过程参数和最终属性之间的关系。在此基础上，将创建现象学模型，用于在多变量优化中使用，以定义TMT的过程窗口，以开发特定的机械和反腐蚀特性。该研究项目的框架旨在建立稳定的TMT流程，从而增强了马氏体不锈钢的适用性。