两相区淬火对高强海洋工程钢组织性能的影响  

Effect of lamellarizing process on microstructure and mechanical properties of high strength marine engineering steel

作　　者：刘丹[1] 罗登[1] 汤伟[1] 高海亮[1] LIU Dan;LUO Deng;TANG Wei;GAO Hailiang(Technical Quality Department of Hunan Valin Xiangtan Iron and Steel Co.,Ltd.,Xiangtan 411101,Hunan,China)

机构地区：[1]湖南华菱湘潭钢铁有限公司技术质量部,湖南湘潭411101

出　　处：《钢铁研究学报》2021年第6期551-556,共6页Journal of Iron and Steel Research

摘　　要：对高强海洋工程用钢分别经过一次淬火+回火(QT)和一次淬火+两相区淬火+回火(QLT)2种热处理工艺处理后,采用扫描电镜(SEM)、连续冷却转变(CCT)曲线、高分辨透射电镜(HRTEM)等手段对其微观组织、相变特性和Cu的析出相进行了检测,并进行了室温拉伸性能及系列温度夏比冲击性能的测定。结果表明:实验钢在0.3~20℃/s的冷速下均得到贝氏体组织,随着冷速的增加,钢的转变温度有所降低,这与工业厚板淬火后表面和心部组织硬度存在一定差异的结果相吻合。经750℃在两相区保温并淬火对钢中的软硬相组织进行调控后,实验钢的屈服强度仍达到800 MPa以上,屈强比从QT态的0.96降低至0.92以下,较QT态的低温韧性有了显著的改善。在两相区保温后,钢中有大量的Cu粒子析出并粗化,然而在后续回火过程中仍有尺寸在20 nm以下的Cu粒子析出,仍可起到一定的析出强化作用。The microstructure,phase transformation characteristics and precipitated phase of high strength marine engineering steel were examined by scanning electron microscopy(SEM),continuous cooling transformation(CCT)curves and high resolution transmission electron microscopy(HRTEM)after being treated by quenching+tempering(QT)and quenching+lamellarizing+tempering(QLT),respectively.The tensile properties at room temperature and charpy impact energy at a series of temperatures were measured.The results show that the bainite can be obtained at the cooling rate of 0.3-20℃/s of experimental steel,and the transformation temperature of steel decreased with the increase in cooling rate,which is consistent with the result that there are some differences in the microstructure and hardness of the surface and the center of the industrial thick plate after quenching.The yield strength of the experimental steel still reached 800 MPa,and the yield strength ratio reduced from 0.96 in QT state to 0.92 in QLT state,and compared with QT state,the low temperature toughness has been improved significantly.A large number of Cu particles precipitated and coarsened during lamellarizing process.However,Cu particles with size below 20 nm still precipitated in the subsequent tempering process,which can still play a role of precipitation strengthening.

关 键 词：两相区淬火 低屈强比 低温韧性 贝氏体 

分 类 号：TG142.1[一般工业技术—材料科学与工程]