新型铸态热作模具钢5Cr9MoNi2SiV的回火脆性  

Temper brittleness of new type as-cast hot-work die steel 5Cr9MoNi2SiV

作　　者：金天文 赵成志[1] 张贺新[1] 任全胜 符策鹄 张泽成 

机构地区：[1]哈尔滨工程大学材料科学与化学工程学院超轻材料与表面技术教育部重点实验室,黑龙江哈尔滨150001

出　　处：《材料热处理学报》2015年第8期167-173,共7页Transactions of Materials and Heat Treatment

基　　金：中央高校基本科研业务费学生科技创新计划(HEUCFS2014)

摘　　要：采用扫描电镜、金相显微镜和XRD等手段研究了5Cr9Mo Ni2Si V热作模具钢在热处理后的组织演化过程,通过俄歇电子能谱实验,分析了不同回火温度下冲击断口晶界元素的变化。结果表明:铸态钢5Cr9Mo Ni2Si V存在严重的组织偏析,主要是Cr、Mo、Mn和V等合金元素沿原奥氏体枝晶间偏聚,常规热处理工艺虽有所改善,但是无法将其消除,导致回火后组织晶界偏析依然存在,严重弱化了晶界;材料在530℃发生的回火脆性是不可逆的,属于第一类回火脆性;材料产生第一类回火脆性的机理主要是杂质元素P偏聚于晶界,降低了晶界结合力;影响P向晶界偏聚的元素主要有Cr和Mo。Microstructure evolution of the as-cast steel 5 CrgMoNi2SiV during heat treatments was analyzed by scanning electron microscopy and metallographic microscope. Meanwhile element distribution at the grain boundaries on impact fracture of the steel tempered at different temperatures was studied by Auger electron spectroscopy. Experiment results show that serious elements segregation exists in the as-cast steel 5CrgMoNi2SiV, main alloy elements such as Cr, Mo, Mn and V are segreagated at the prior austenite dendrite, and conventional heat treatment can improve the segregation, but is unable to eliminate it, resulting in the weakening of the grain boundaries, and the temper embrittleness can not be eliminated completely. The tempering embrittleness occuring at 530 ℃ is irreversible and it belongs to the tempered martensite brittleness. The mechanism of temper embrittleness for the steel is mainly the segregation of impurity element P along the grain boundaries, and Cr and Mo are the mainly elements which affect the P element segregation at grain boundaries.

关 键 词：热作模具钢 组织偏析 回火脆性 断裂机理 

分 类 号：TG111.91[金属学及工艺—物理冶金]