粉末冶金钢烧结过程控制和分析

烧结过程控制对粉末冶金整个工艺过程起着至关重要的作用,控制不好,将导致烧结后的零件在尺寸和性能上不稳定或达不到产品设计要求,并可能还会出现氧化、脱碳、渗碳、崩裂和积碳等工业中常见的问题。随着对粉末冶金产品的性能和成本控制要求不断提高,金属Cr因其价格低并具有很好的强化效果,成为粉末冶金工业开拓的重点方向。但是金属Cr容易氧化,对烧结气氛要求较高,因此对烧结工艺提出了挑战。随着烧结炉技术的发展和氮基保护气体广泛使用,在网带炉中烧结含Cr成分的零件已经成为现实。利用热电偶、氧分压和CO分析仪等设备组成的分析系统,评估了以氮氢混合气体作为保护气氛的网带烧结炉的实际烧结情况,分析了几种烧结过程中常见的缺陷及其原因,并提出了相应的改善措施,同时也总结了含Cr材料所需的烧结条件及其控制。

Control and analysis of powder metallurgy steel sintering process

The control of sintering process is very critical for PM technology. Bad control during sintering will cause inconsistence in dimension and mechanical properties of sintered parts,and even some failure issue,like ox-idation,decarburization,carburization,blistering and sooting. With the higher requirement on the performance and cost of PM products,chromium with high hardenability and low cost becomes an interesting development of PM industry. However,Cr is easy to be oxidized,and has strict requirement on sintering atmosphere,so it is a challenge to the sintering process. With the development of sintering furnace and the wide use of nitrogen based protective gas,the sintering of PM part with Cr components in the net belt furnace has become a reality. Practical field experiences with sintering furnace atmosphere based on nitrogen and hydrogen mixed gas were given by uti-lizing a measuring system consisting of thermal couple,oxygen and CO probes. The cause and effect relationships for many common atmosphere-related problems were explored and solutions offered for corrective action,as well as the sintering requirement of materials with Cr were summarized.