定向凝固法控制M2高速钢中共晶碳化物形貌演变行为  

Controlling of Morphology Evolution of Eutectic Carbide in M2 High Speed Steel by Directional Solidification

作　　者：李婉琴 夏智斌 齐文涛 李强[1,2] 郑天祥 钟云波[1,2] LI Wanqin;XIA Zhibin;QI Wentao;LI Qiang;ZHENG Tiangxiang;ZHONG Yunbo(School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China;State Key Laboratory of Advanced Special Steel,Shanghai University,Shanghai 200444,China)

机构地区：[1]上海大学材料科学与工程学院,上海200444 [2]省部共建高品质特殊钢冶金与制备国家重点实验室,上海200444

出　　处：《上海金属》2020年第1期77-83,共7页Shanghai Metals

基　　金：国家十三五重点研究发展计划(2016YFB0300401);钢铁联合项目(U1860202);大科学装置联合重点项目(U1732276);青年基金(51704193);科委基础研究领域项目(13JC14025000);科委资助(15520711000)

摘　　要：采用真空布里奇曼定向凝固技术,通过控制凝固过程中的抽拉速度,制备了不同冷却速率下凝固的M2高速钢,研究了M2高速钢凝固过程中共晶组织形貌的演变及演变机制。结果表明:根据试样的抽拉速度与温度梯度之间的关系,能够实现定向凝固过程中冷却速度的精确控制,且抽拉速度与冷却速度成正比。增大抽拉速度可促进共晶碳化物由层片状向短棒状转变。当抽拉速度低于500μm/s时,共晶碳化物形貌为粗大层片状;当抽拉速度远高于500μm/s时,共晶碳化物形貌为短棒状;当抽拉速度为500μm/s时,共晶碳化物形貌为两者的混合。两种不同形貌的共晶碳化物都是M 2C型碳化物。增大抽拉速度能够促进共晶碳化物的析出,同时共晶碳化物中合金元素含量降低。当抽拉速度从20μm/s增加到10000μm/s时,马氏体(110)晶面间距从2.0607减小至2.0553。M2 high speed steel solidified at different cooling rates was prepared with Bridgman directional solidification technique by controlling the pulling speed in the process of solidification,and the morphological evolution behavior and evolution mechanism of eutectic carbides during solidification of the steel were studied.The results showed that the precise control of the cooling rate during directional solidification process could be achieved according to the relationship between the pulling speed and the temperature gradient,and the cooling rate was proportional to the pulling speed,and that the transition of eutectic carbide from lamella-like to short rod-like could be promoted by increasing the pulling speed.When the pulling speed was less than 500μm/s,the morphology of eutectic carbides was coarse lamella-like.When the pulling speed was much higher than 500μm/s,the morphology of eutectic carbides was short rod-like.When the pulling speed was 500μm/s,the morphology of eutectic carbides was a mixture of the above two.Both the lamellar-like eutectic carbides and the short rod-like eutectic carbides were M 2C type.The precipitation of eutectic carbides was promoted by increasing the pulling speed,and at the same time,the content of alloying elements in eutectic carbides decreased.The spacing of martensite(110)crystal planes decreased from 2.0607 to 2.0553 as the pulling speed increased from 20μm/s to 10000μm/s.

关 键 词：M2高速钢 真空定向凝固 抽拉速度 共晶碳化物 形貌 

分 类 号：TG1[金属学及工艺—金属学]