添加Ti对金属注射成形HK30不锈钢烧结致密化的影响  

Effect of Ti addition on sintering densification of MIM HK30 stainless steel

作　　者：李大鹏[1] 何浩[1] 李益民[1] 沈红仁[1] 张翔[1] 

机构地区：[1]中南大学粉末冶金国家重点实验室,湖南长沙410083

出　　处：《中南大学学报（自然科学版）》2013年第8期3151-3158,共8页Journal of Central South University:Science and Technology

基　　金：国家自然科学基金资助项目(51075);中南大学博士后基金资助项目(760413008)

摘　　要：在HK30粉末中分别添加质量分数为0.4%,0.8%和1.2%的Ti粉,采用粉末注射成形工艺制备试样,对制得的试样进行密度、显微组织、显微硬度和收缩率检测。基于黏弹性理论对烧结致密化过程进行分析,推导出烧结过程中致密化速率的表达式。研究结果表明:添加Ti会加快烧结初期的致密化速率,降低烧结激活能,但使最终的烧结密度下降;Ti颗粒周围的奥氏体硬度下降。在烧结过程中Ti具有更高的亲和力,优先结合材料中的碳氧等元素,减少奥氏体中的杂质含量,在烧结初始阶段有利于致密化的进行。在烧结后期,超固相线液相烧结对致密化的贡献最大,因为碳含量的减少,使液相生成量减少,从而阻碍了密度的继续提高。The HK30 stainless steel powder was mixed with 0.4%, 0.8%, 1.2% （mass fraction） Ti, and the samples were prepared by powder injection molding. The density, microstructure, microhardness and shrinkage rate of the samples were measured. The densification process was modeled based on viscoelasticity theory. The equation of densification rate was established. The results show that Ti addition reduces the sintering activation-energy and improves the sintering densification in initial stage, but it reduces the final density. The microhardness of austenite near Ti particle is lower than that of other areas. Because Ti has a higher affinity for C and O, which reduces the impurity levels in the austenite. The reduction of impurities is conducive for densification during the initial stage of sintering. In the final stage, supersolidus liquid-phase sintering has the largest contribution on densification. Because carbon is combined with Ti, the amount of liquid phase is reduced and therefore the sintering densification is hindered.

关 键 词：烧结致密化 HK30不锈钢 黏弹性理论 金属注射成形 

分 类 号：TF121[冶金工程—粉末冶金]