奥氏体变形状态对EH960海工钢组织与性能的影响  

Effect of austenite deformation on the microstructure and mechanical properties of EH960 steel for offshore engineering

作　　者：肖大恒[1] 宫晓兰 杨建华[1] 高海亮[1] 阚立烨 叶其斌[2] XIAO Daheng;GONG Xiaolan;YANG Jianhua;GAO Hailiang;KAN Liye;YE Qibin(Hunan Valin Xiangtan Iron and Steel Co.,Ltd.,Xiangtan 411101,China;State Key Laboratory of Rolling and Automation,Northeastern University,Shenyang 110819,China)

机构地区：[1]湖南华菱湘潭钢铁有限公司,湖南湘潭411101 [2]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：《轧钢》2022年第5期13-19,26,共8页Steel Rolling

基　　金：辽宁省科技重大专项资助项目(2020JH1/10100001)。

摘　　要：控制轧制中未再结晶区变形量是调控DQ-T钢板组织与性能的关键参数。针对EH960钢板,将3块60 mm厚钢坯热轧至40 mm厚度中间坯,待温至850℃后再轧至10、15、30 mm厚度,随后进行直接淬火(DQ10、DQ15和DQ30)和620℃回火(DQ10-T、DQ15-T和DQ30-T)热处理,研究了控制轧制中未再结晶区变形量对DQ钢板及DQ-T钢板组织与性能的影响。结果表明:提高未再结晶区变形量,可以有效地细化直接淬火后DQ钢板的马氏体板条组织。高温回火后的DQ-T钢板中遗传自马氏体板条的高密度晶体缺陷促进了碳化物的析出,提高了屈服强度;由于其原始奥氏体变形而呈现压扁形态,在冲击过程中产生断口分层扩大了纤维区,从而提高了低温韧性。但是,奥氏体变形量过大会导致淬火时马氏体相变偏向于某一取向,不利于马氏体区块等亚结构的形成,从而减少了大角度晶界的密度,不利于钢板低温冲击韧性。DQ15-T钢板具有较好的综合力学性能,其屈服强度为1070 MPa,抗拉强度为1098 MPa,-40℃冲击功为100 J。For direct-quenched and tempered(DQ-T)plate,the extent of deformation below the non-recrystallization temperature(T_(nr))is crucial for adjusting its microstructure and mechanical properties.For the EH960 steel plate,three 60 mm-thick slabs were hot rolled into 40 mm-thick plates above T_(nr),which were subsequently hot rolled into final plates with thickness of 10 mm,15 mm,and 30 mm,respectively,after being held in the air until temperatures dropped to about 850℃.The three finishing rolled plates were directly quenched in water(referring to DQ10,DQ15,and DQ30)and then were subsequently tempered for 2 h at 620℃(referring to DQ10-T,DQ15-T,and DQ30-T).The influence of deformation extent below T_(nr) on the microstructure and mechanical properties of DQ and DQ-T plates were investigated.The results show that increasing deformation extent below T_(nr) can effectively refine direct-quenched martensitic structure,within which the high-density crystal defects inherited from the deformed austenite,promoted the precipitation of carbides during tempering,increasing the yield strength of plate.Due to the pancaked austenite grains,delamination fracture occurred during impact tests,the low-temperature toughness is thus improved by increasing the area of fiber zone.However,excessive deformation in the non-recrystallization region strengthens a specific orientation of martensite transformation during direct quenching,which reduces the amount of substructure blocks and large-angle grain boundaries,unfavorable for low temperature impact toughness of plate.The DQ15-T plate,which has a yield strength of 1070 MPa,a tensile strength of 1098 MPa,and an impact energy of 100 J at-40℃,thereby exhibits the optimum combination of mechanical properties.

关 键 词：EH960海工钢 未再结晶区 变形量 变形奥氏体 调质处理 直接淬火 显微组织 力学性能 

分 类 号：TG142.1[一般工业技术—材料科学与工程]