钼钨钒合金化热作模具钢高温回火组织演变  

Microstructural evolution of Mo−W−V alloyed hot-work die steel during hightemperature tempering

作　　者：李爽 时彦林[1] 杨晓彩[1] 石永亮[1] 王真 张士宪[1] 施渊吉 吴晓春[4] LI Shuang;SHI Yan-lin;YANG Xiao-cai;SHI Yong-liang;WANG Zhen;ZHANG Shi-xian;SHI Yuan-ji;WU Xiao-chun(Hebei College of Industry and Technology,Shijiazhuang 050091,China;Hebei Material Fine Crystal Preparation Technology Innovation Center,Shijiazhuang 050091,China;Nanjing Institute of Industry Technology,Nanjing 210046,China;School of Materials Science and Engineering,Shanghai University,Shanghai 200072,China)

机构地区：[1]河北工业职业技术学院,石家庄050091 [2]河北省材料细晶制备技术创新中心,石家庄050091 [3]南京工业职业技术学院,南京210046 [4]上海大学材料科学与工程学院,上海200072

出　　处：《工程科学学报》2020年第7期902-911,共10页Chinese Journal of Engineering

基　　金：河北省教育厅青年基金资助项目(QN2020257,QN2018221);河北工业职业技术学院博士基金资助项目(BZ201801)。

摘　　要：为适应热冲压技术的发展需求,开发了一种新型高热导率高耐磨性能热冲压用模具钢材料.采用扫描电镜(SEM)、透射电镜(TEM)等检测手段对钼钨钒合金化新型模具钢的高温回火性能与组织特征进行了研究.阐明了新型热冲压模具钢回火过程碳化物析出与演变规律.实验结果表明:实验用钼钨钒合金化模具钢材料具有良好的回火二次硬化性能,在500~600℃温度区间回火时,回火组织硬度上升;在600℃回火出现二次硬化峰值;当回火温度超过600℃后,组织软化程度明显,回火硬度开始下降.实验模具钢在高温回火过程中的硬度变化与其合金碳化物的偏聚、析出和聚集长大密切相关.当在560℃以下回火时,实验钢组织中未有合金碳化物析出;当回火温度大于560℃时,回火组织中开始析出M_2C型碳化物;当回火温度高于600℃后开始析出MC型碳化物;当在620℃长时间回火后M_2C型碳化物转化为M_6C型碳化物,此时实验钢硬度开始明显下降;而当回火温度高于660℃时,新型实验钢组织中主要为M_6C和MC型合金碳化物.Hot-work die steels are widely used to meet the requirements of industrial applications in which the steels must endure high temperature and mechanical loads,such as the hot stamping of very-high-strength steel.In the field of hot-stamping technology applications,the tool materials must have excellent high-temperature performance,such as the high-temperature stability of the microstructure.Research on hot-stamping die materials began somewhat late in China because high-quality die steel products had typically been imported.A new type of hot-stamping die steel with high thermal conductivity and high wear resistance was developed to meet the requirements of hot-stamping technology.In this study,we used scanning electron microscopy(SEM)and transmission electron microscopy(TEM)to determine the high-temperature tempering performance and microstructural characteristics of this new Mo−W−V alloyed hot-work die steel.Based on the results,we derived the precipitation and evolvement rules of the carbides in the new type hotstamping die steel during the tempering process,which indicate that the new Mo−W−V alloyed test steel has an excellent secondary hardening property.We find the hardness of the microstructure to increase after tempering at 500℃–600℃;however,at tempering temperatures above 600°C,the matrix obviously softens and the hardness of the test-steel microstructure decreases.The hardness of the test die steel is strongly linked to the segregation,precipitation and growth of the alloy carbides in the matrix.No alloy carbide precipitation is observed at tempering temperatures below 560℃;however,M2C-type carbide precipitation is observed at tempering temperatures higher than 560℃.MC-type alloy carbide is observed in the test-steel matrix at tempering temperatures up to 600℃.At tempering temperatures above 620℃,the M2C-type alloy carbides transform into M6C-type alloy carbides and the hardness curve of the test steel sharply declines.The MC-type and M6C-type alloy carbides are the main carbides in

关 键 词：模具钢 热处理 合金碳化物 组织 透射电镜 

分 类 号：TG142.1[一般工业技术—材料科学与工程]