Hot Powder Vehicle Compaction of an Atomized Stainless Steel Powder

研究了不锈钢粉末在热粉末台车压制过程中的致密化和组织演变。将预热后的粉末预制体在硼硅酸盐玻璃中真空烧结，然后用预热的氧化铝颗粒作为传压介质在钢模中压制。确定了全致密化的条件作为压力和温度的函数。压力的增加比温度的增加更有效。在压制过程中观察到三种显微组织特征：枝晶组织的溶解、再结晶和正常晶粒生长，而这又主要取决于预热温度。已经发现，在再结晶阶段期间形成亚微米尺寸的显微组织。本文从压力烧结图的概念出发，讨论了目前压制工艺的致密化机理。

Densification and microstructural development of stainless steel powder during hot powder vehicle compaction was investigated. The preheated powder preform, vacuum encapsuled in a borosilicate glass, was compacted in a steel die using preheatedalumina granules as a pressure transmitting medium. The condition for the full-densification was determined as a function of pressure and temperature. The increase in pressure was more effective than in temperature. Three microstructural features were odserved during the compacting process; Solutioning of dendritic structure, recrystallization and normal grain growth, which in turn was found to be mainly dependent of preheating temperature. It has been found that a submicron-sized microstructure is formed during the recrystallization stage. the densification mechanism of the present compaction process has been discussed on a concept of pressure sintering map.