高冷速下X80管线钢等温相变及高温卷取关键冷却工艺  

Isothermal transformation behavior and key controlled-cooling process of X80 pipeline steel under high cooling rate

作　　者：赵金华[1] 侯耀武 袁国[3] 王学强[3] 邸洪双[3] ZHAO Jin-hua;HOU Yao-wu;YUAN Guo;WANG Xue-qiang;DI Hong-shuang(School of Materials Science and Enginerring,Taiyuan University of Science&Technology,Taiyuan 030024,China;Avic Shanxi Hongyuan Aviation Forging Company Ltd,Xi'an 713801,China;The State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China)

机构地区：[1]太原科技大学材料科学与工程学院,山西太原030024 [2]航空工业陕西宏远航空锻造有限责任公司,陕西西安713801 [3]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

出　　处：《材料热处理学报》2020年第8期87-94,共8页Transactions of Materials and Heat Treatment

基　　金：山西省来晋优秀博士科研资助项目(20192041);太原科技大学博士科研启动基金项目(20182007)。

摘　　要：采用高分辨热膨胀相变仪对高冷速下X80管线钢等温相变行为进行了研究,利用扫描电镜(SEM)、透射电镜(TEM)对不同相变条件下实验钢微观组织、亚结构进行了表征。基于膨胀量变化规律及微观组织特征,讨论了不同等温相变条件下过冷奥氏体组织演变规律,并进一步给出了高温卷取关键冷却工艺。结果表明,在40℃/s冷却速率下,当等温温度由580℃降低至370℃时,实验钢相变开始温度为621.1~624.5℃;等温温度为580℃时,等温过程过冷奥氏体相变不完全,相变产物为针状铁素体(AF)+贝氏体铁素体(BF)+板条贝氏体(LB)的混合组织;当等温温度降低至510、440及370℃时,实验钢相变产物为AF+BF+M/A岛的复相组织,LB消失,且随着相变温度降低M/A岛体积分数及尺寸均减小。对于X80管线钢而言,需保证控制冷却过程中终冷温度低于510℃,在避免过冷奥氏体相变不完全现象发生的同时,使组织保持以AF+BF+细小M/A岛的复相组织特征。Isothermal transformation behavior of X80 pipeline steel at high cooling rate was investigated by high-resolution dilatometer.Microstructure and substructure of the X80 pipeline steel under different phase transformation conditions were studied by means of scanning electron microscopy(SEM)and transmission electron microscopy(TEM).Based on the variation trends of the expansion and the microstructure characteristic,the evolution law of supercooled austenite under different isothermal phase transformation conditions was discussed,and the key cooling process of high temperature coiling was further given.The results show that at cooling rate of 40℃/s,when the isothermal temperature decreases from 580℃to 370℃,the phase transformation start temperature of the experimental steel is 621.1-624.5℃.When the isothermal temperature is 580℃,the phase transformation of supercooled austenite in isothermal process is incomplete,and the microstructure of the experimental steel is composed of acicular ferrite(AF),bainitic ferrite(BF)and lath bainite(LB).When the isothermal temperature decreases to 510,440 and 370℃,the microstructure of the experimental steel is composed of AF,BF and M/A island,the LB disappears,and the volume fraction and size of the M/A island decrease with the decrease of phase transformation temperature.For the X80 pipeline steel,it is necessary to ensure that the final cooling temperature is lower than 510℃during the control cooling,to avoid the incomplete phase transformation of supercooled austenite,and to obtain the complex microstructure of AF,BF and fine M/A islands.

关 键 词：X80管线钢 高冷速 针状铁素体 热轧工艺 

分 类 号：TG142.4[一般工业技术—材料科学与工程]