临界区等温球化退火对低密度轴承钢组织和硬度的影响  

Effect of isothermal annealing on microstructure and hardness of low-density bearing steel

作　　者：庞佳琛 王国栋[1] 易红亮[1,2] PANG Jia-chen;WANG Guo-dong;YI Hong-liang(State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,Liaoning,China;Easyforming Materials Technology Co.,Ltd.,Suzhou 215123,Jiangsu,China)

机构地区：[1]东北大学轧制技术及连轧自动化国家重点实验室,辽宁沈阳110819 [2]育材堂(苏州)材料科技有限公司,江苏苏州215123

出　　处：《钢铁研究学报》2020年第12期1077-1083,共7页Journal of Iron and Steel Research

基　　金：国家自然科学基金资助项目(51722402)。

摘　　要：临界区等温球化退火是实现高碳轴承钢中片状珠光体球化的主要热处理方式,其将片状珠光体转变为粒状珠光体,改善轴承件的可加工性及组织均匀性。研究了临界区等温球化退火工艺对低密度含Al轴承钢微观组织演化及硬度的影响。研究结果表明,轴承钢钢中高含量Al的添加可以提高临界区等温球化退火温度,缩短球化时间,将珠光体的硬度降低至300HV以下。但是,临界区等温球化保温过程中有石墨颗粒形成,石墨颗粒的产生虽然能够有效地降低球化后钢材硬度,但是部分石墨颗粒在最终的奥氏体化过程中难以溶解进入钢材基体,未溶解的石墨颗粒不仅增加了组织的不均匀性,而且降低了轴承钢硬度。所以,较长时间退火保温的临界区球化退火方式并不适用于低密度高碳高Al轴承钢。Isothermal spheroidization annealing treatment is a vital step for bearing steels to transform the lamellar pearlite into granular pearlite, which can improve the uniformity and cutability of bearings. The effect of isothermal spheroidization annealing on the microstructure and hardness of a low-density bearing steel with 5 wt.% addition was studied. The result shows that, Al addition has a great effect on increasing annealing temperature and shortening holding time of spheroidization annealing and decreasing the hardness of pearlite lower than 300 HV. However, there is graphitization during the isothermal annealing process, graphite particles decrease the carbon content in steel matrix and has a great contribution to decrease hardness. However, graphite particles cannot be completely dissolved into steel matrix during the final austenitization treatment, the undissolved graphite particles have a deterioration effect on the uniformity of microstructure and decrease the final hardness. Considering the uniformity of structure and mechanical properties, the isothermal spheroidising annealing treatment should not be chosen for spheroidizing the low-density high Al addition bearing steels.

关 键 词：低密度轴承钢 临界区等温球化退火 石墨 均匀性 

分 类 号：TG142.1[一般工业技术—材料科学与工程] TG156.2[金属学及工艺—金属材料]