Nb变质处理铸造高速钢的组织和性能

在铸造高速钢刀具中添加质量分数为4％的Nb形成孤立粒状碳化物以细化铸态组织,研究了不同固溶温度和回火温度下的组织和硬度.结果显示:固溶处理温度为1 200℃时,碳化物呈孤立粒状均匀分布；低于此温度,晶界上的羽毛状碳化物未能完全溶解,而高于此温度则导致粒状NbC的溶解.回火温度为570℃到580℃时,可获得细针状马氏体和最少量的残余奥氏体；低于此温度,针状马氏体粗大,残余奥氏体量较多.

The Effects of Nb Modification on the Structure and Properties of Cast High Speed Steel

Nb was applied to the cast high speed steel(HSS) cutter to refine the as-cast structure.The structure and hardness at different solid solution temperatures and tempering temperatures were studied.The results show that with solid solution temperature ranging from 1 200 ℃ to 1 220 ℃,the carbide distributes homogeneously as isolated granular.While the temperature is lower than this range,the feathery carbide in the grain boundaries can not be fully dissolved,but while it is higher than this range,granular NbC starts to dissolve.Tempered at the temperatures ranging from 570 ℃ to 580 ℃,fine acicular martensite and least amount of residual austenite can be obtained.While the temperature is lower than this range,coarse martensite and more amount of residual austenite can be obtained.