Cr8支承辊用钢的连续冷却过程相变行为  

Phase transformation behavior during continuous cooling of Cr8 back-up roll steel

作　　者：郭亚非 李志龙 张博 李洁 庞庆海 Guo Yafei;Li Zhilong;Zhang Bo;Li Jie;Pang Qinghai(CITIC Heavy Industries Co.,Ltd.,Luoyang Henan 471039,China;Luoyang Zhong Chong Casting and Forging Co.,Ltd.,Luoyang Henan 471039,China)

机构地区：[1]中信重工机械股份有限公司,河南洛阳471039 [2]洛阳中重铸锻有限责任公司,河南洛阳471039

出　　处：《金属热处理》2023年第8期47-51,共5页Heat Treatment of Metals

基　　金：国家重点研发计划(2020YFB2008400)。

摘　　要：为探究Cr8支承辊用钢在连续冷却过程的相变行为,采用Formastor-FⅡ全自动相变仪测定其在不同冷速下的相变参数,结合热膨胀法和金相法建立CCT曲线,分析了不同冷速对其组织及硬度的影响。结果表明,在2~60℃/min区间内,Cr8支承辊用钢显微硬度随着冷速增加而逐渐增加,硬度值由238 HV2升高至570 HV2。当冷却速率小于8℃/min时,过冷奥氏体转变为含有珠光体的混合组织;冷却速率在8~60℃/min之间时,珠光体转变消失,过冷奥氏体转变为硬度较高的贝氏体+马氏体或单独的马氏体组织。相比于Cr5钢,Cr8支承辊用钢的过冷奥氏体具有更好的稳定性,拥有较低的临界冷却速率和良好的力学性能,是制造大型支承辊锻件的理想材料。In order to investigate the phase transformation behavior of Cr8 back-up roll steel during the continuous cooling process,the phase transformation parameters of the Cr8 back-up roll steel at different cooling rates were measured by Formastor-FⅡautomatic phase transformation analyzer.The CCT curves was established by thermal expansion method and metallographic method,and the influence of different cooling rates on microstructure and hardness of the Cr8 back-up roll steel was analyzed.The results show that the microhardness of Cr8 back-up roll steel increases gradually with the increase of cooling rate in the range of 2-60℃/min,and the hardness value increases from 238 HV2 to 570 HV2.The supercooled austenite transforms into a mixed structure containing pearlite when the cooling rate is less than 8℃/min.The pearlite transformation disappears and the supercooled austenite transforms into bainite+martensite or single martensite with higher hardness when the cooling rate is between 8℃/min and 60℃/min.Compared with Cr5 steel,the supercooled austenite of the Cr8 back-up roll steel has better stability,the steel has lower critical cooling rate and good mechanical properties,and is an ideal material for manufacturing large backup roll forgings.

关 键 词：Cr8支承辊用钢 热膨胀法 CCT曲线 组织 硬度 

分 类 号：TG151.2[金属学及工艺—热处理]