权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

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.

高合金马氏体不锈钢除了耐腐蚀外，还具有高硬度和高强度的特点。由这些钢制成的零件的制造主要是通过在软退火条件下对钢进行冷成形来进行的。只有在成形后，材料才会进行淬火和回火，以调整所需的最终机械性能。然而，使用冷成形时，最大可达到的成形程度往往不足以制造复杂几何形状的零件。这一限制可以通过热机械处理(TMT)来克服，即精确控制成形和温度状态的热成形过程。由于激活了各种物理冶金现象(如相变、再结晶或碳化铬的形成)，对成形性和由此产生的机械性能(硬度、强度、耐腐蚀性)有很大影响，TMT对用户提出了技术和材料科学方面的挑战。本课题将系统地研究TMT工艺参数(奥氏体化温度、保温时间、变形程度、变形温度和应变速率)对马氏体钢的成形性、力学性能和腐蚀性能的影响。一个目标是确定稳定的TMT过程的基本要求。此外，还必须确定在TMT过程中激活的物理冶金现象和微观组织变化，以及它们对析出和相变动力学的影响。在工作计划中，考虑热预应变(DCCT)和奥氏体化温度(TTA)影响的连续冷却转变(CCT)图将通过膨胀法、金相和仪表化硬度测试来确定。此外，所得到的微结构将通过光学显微镜和电子显微镜进行表征。实验程序得到热力学计算的补充。成形性将通过热流曲线、杯突和拉深试验以及流动极限图(FLD)的确定来评估。将进行硬度测量和拉伸测试，以表征所产生的性能。腐蚀行为将在动电位极化测试的基础上进行评估。借助实验的统计设计，将确定实验方案，并确定工艺参数与最终性能之间的关系。在此基础上，将创建现象学模型，用于多变量优化，以确定TMT的工艺窗口，以开发特定的机械和防腐性能。这一研究项目的框架旨在建立稳定的TMT工艺，从而提高马氏体不锈钢的适用性。