淬火冷却速率对海洋平台用Ni-Cr-Mo-B钢性能的影响  

Effect of Quenching Cooling Rate on Mechanical Properties of a Ni-Cr-Mo-B Steel for Offshore Platform

作　　者：张守清 胡小锋[1] 杜瑜宾 姜海昌[1] 庞辉勇 戎利建[1] ZHANG Shouqing;HU Xiaofeng;DU Yubin;JIANG Haichang;PANG Huiyong;RONG Lijian(CAS Key Laboratory of Nuclear Materials and Safety Assessment,Institute of Metal Research,Chinese Academy of Sciences,Shenyang 110016,China;School of Materials Science and Engineering,University of Science and Technology of China,Shenyang 110016,China;Wuyang Iron and Steel Co.Ltd.,Pingdingshan 462500,China)

机构地区：[1]中国科学院金属研究所中国科学院核用材料与安全评价重点实验室,沈阳110016 [2]中国科学技术大学材料科学与工程学院,沈阳110016 [3]舞阳钢铁有限责任公司,平顶山462500

出　　处：《材料研究学报》2022年第4期250-260,共11页Chinese Journal of Materials Research

基　　金：国家重点研发计划(2016YFB0300601);辽宁省兴辽英才计划项目(XLYC1907143);中国科学院战略重点研究项目(XDC04000000);辽宁省自然科学基金(2020-MS-008)。

摘　　要：使用热膨胀仪、SEM电镜、EBSD、硬度、拉伸和冲击等观察和检测手段,研究了淬火冷却速率对海洋平台用Ni-Cr-Mo-B钢的显微组织、有效晶粒尺寸(EGS)和力学性能的影响。结果表明,不同冷却速率的合金钢,其显微组织包括板条马氏体(LM)、板条贝氏体(LB)、粒状贝氏体(GB)和F(铁素体)。随着淬火冷却速率的降低合金钢的显微组织分别为LM(>20℃/s)、LM/LB(20~2℃/s)、LB(2~1℃/s)、LB/GB(1~0.2℃/s)、GB/F(0.2~0.02℃/s),其硬度由100℃/s时的393HV逐渐降低至0.02℃/s时的291HV。回火后合金钢的屈服强度由水冷的836 MPa降低至炉冷的726 MPa,而延伸率几乎不变,约为20%。油冷合金钢的-60℃冲击功最高(199 J),水冷次之(54 J),空冷和炉冷合金钢的最低(<30 J)。其原因是,油冷合金钢具有LM_(T)/LB_(T)混合组织,较小的EGS(1.6μm)对解理裂纹的阻碍作用较强;而空冷、炉冷合金钢的组织分别为GB_(T)/LB_(T)、GB_(T)/F,其EGS较大(分别为2.4和2.8μm),对解理裂纹的阻碍作用较弱。The effect of quenching cooling rate on the microstructure,effective grain size(EGS)and mechanical properties of a Ni-Cr-Mo-B steel for offshore platform was investigated by means of dilatome-ter,SEM,EBSD,in combination with hardness,tensile and impact tests.The results show that the micro-structures of the steel by different cooling rates mainly include lath martensite(LM),lath bainite(LB),granular bainite(GB)and ferrite(F).With the decrease of cooling rate the microstructures of the steel can be LM(>20℃/s),LM/LB(20~2℃/s),LB(2~1℃/s),LB/GB(1~0.2℃/s)and GB/F(0.2~0.02℃/s).Meanwhile,the hardness gradually decreases from 393HV by 100℃/s to 291HV by 0.02℃/s.After tem-pered,the yield strength decreases from 836 MPa for water-cooled steel to 726 MPa for furnace-cooled steel,while the elongation almost keeps constant around about 20%.Impact energy at-60℃ for oil-cooled steel is the highest about 199 J,followed by water-cooled steel(54 J),and the air-cooled and fur-nace-cooled steels exhibit the lowest impact energy(<30 J).This is because the microstructure of oil-cooled steel is LM_(T)/LB_(T),which has the smallest EGS(1.6μm)and the strongest effect of hindering the crack growth.However,the air-cooled and furnace-cooled steels present microstructures GB_(T)/LB_(T) and GB_(T)/F respectively,which show the larger EGS(2.4 and 2.8μm)and the weaker effect of hindering the crack growth.

关 键 词：金属材料 Ni-Cr-Mo-B钢 显微组织 冷却速率 有效晶粒尺寸 冲击功 

分 类 号：TG142.1[一般工业技术—材料科学与工程]