Interaction between the microstructure and the properties of plasma nitrided austenitic stainless steels

等离子氮化奥氏体不锈钢显微组织与性能之间的相互作用

基本信息

批准号：
321139694
负责人：
Professor Dr. Günter Bräuer
金额：
--
依托单位：
Institut für Oberflächentechnik
依托单位国家：
德国
项目类别：
Research Grants
财政年份：
2016
资助国家：
德国
起止时间：
2015-12-31 至 2018-12-31
项目状态：
已结题

来源：
https://gepris.dfg.de/gepris/projekt/321139694?language=en
关键词：
Interaction between microstructure properties plasma

项目摘要

The research project focuses on a comprehensive study of the interactions between the plasma nitriding process, the material microstructure and the resulting properties, especially concerning the corrosion behavior, of austenitic stainless steels. The preliminary results show that the wear resistance is dominated by the thickness of the S-phase. It was found, that with increasing degree of deformation due to cold rolling or shot peening prior to nitriding, the thickness of the S- phase increases with otherwise identical nitriding conditions .There were significant influences of the materials microstructure and the surface condition on the corrosion properties. In particular, the increase in defect density due to plastic deformation reduces the corrosion resistance of plasma nitrided steels in the salt spray test. Contrary to the prevailing phenomenological assumption, that a reduction of the treatment temperature improves the corrosion behavior, is was found that a low temperature process (370 °C, 960 min) causes significantly worse corrosion behavior in salt spray test than a high temperature process (420 ° C, 360 min). With both parameter sets good matching thicknesses of the S phase were obtained. The reason for this behavior is seen in the formation of precipitates, resulting in a chromium depletion of the matrix. In order to formulate a mechanism based description of the precipitation mechanism in dependence of initial microstructure and treatment parameters, systematic TEM investigations will be carried out. Furthermore, potentiodynamic polarization tests in H2SO4 reveal, that all material states (nitrided and unnitrided ) were resistant to corrosion. Potentiodynamic polarization tests of nitrided sampels in NaCl, on the other hand, are in good accordance with the salt-spray test results in terms of the corrosion behavior. However, all unnitrided samples showed systematically a higher corrosion current than the nitrided samples.Based on the results and the derived hypotheses, the focus of the proposal is to gain a fundamental understanding by means of microstructural and microanalytical studies concerning the microstructural changes and their kinetics as function of microstructure and nitriding parameters. Based on this, another focus is the identification of standardized analysis methods which allow for a correlation between the microstructure and the resulting corrosion properties. The overall objective of the project is to formulate a conceptual model, which describes the relationship between microstructure, chemical composition and the nitriding process on the resulting corrosion and wear behavior.

该研究项目重点介绍了血浆硝化过程，材料微结构和所得特性（尤其是与奥氏体不锈钢腐蚀行为）之间相互作用之间的相互作用的全面研究。初步结果表明，耐磨性由S期的厚度支配。已经发现，由于硝化作用前冷滚动或固定的变形程度增加，S期的厚度随着其他相同的硝化条件的增加而增加。材料微结构的显着影响以及腐蚀特性上的表面条件的显着影响。特别是，由于塑性变形而导致的缺陷密度增加可在盐喷雾测试中降低血浆硝化钢的耐腐蚀性。与普遍的现象学假设相反，治疗温度的降低改善了腐蚀行为，发现低温过程（370°C，960分钟）在盐喷雾测试中导致腐蚀行为明显比高温过程（420°C，360分钟）差明显差。在两个参数集的情况下，都获得了S相的良好匹配厚度。这种行为的原因是在精度的形成中看到的，导致矩阵的铬部署。为了形成对初始微观结构和治疗参数依赖精确机制的基于机制的描述，将进行系统的TEM研究。此外，H2SO4中的电位动力学极化测试表明，所有材料状态（硝化和未硝化）都对腐蚀性有抵抗力。另一方面，NaCl中硝化样品的电位动力学极化测试良好，根据腐蚀行为的盐分测试结果。但是，所有未硝基的样品在系统上显示出比硝化样品更高的腐蚀电流。基于结果和衍生的假设，该提案的重点是通过微观结构和微观分析研究获得基本的理解，这些研究将微观结构变化及其Kinetics作为微观结构和nitridesnitridesnitridesitives nitridesitionds nitridesitionds nitridesity nitridesitives nitridesdionds nitridess nitridess参数获得。基于此，另一个重点是标准化分析方法的识别，该方法允许微观结构与所得腐蚀属性之间的相关性。该项目的总体目标是形成一个概念模型，该模型描述了微观结构，化学成分和硝化过程对产生的腐蚀和磨损行为的关系。