船用高强韧钢二次淬火过程对屈强比的影响  

Effect of secondary quenching on the yield ratio of high-toughness marine steel

作　　者：李朝阳 郭呈宇 康永林[2] 王书桓 于浩[2] LI Chaoyang;GUO Chengyu;KANG Yonglin;WANG Shuhuan;YU Hao(School of Metallurgy and Energy,North China University of Science and Technology,Tangshan 063210,China;School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China)

机构地区：[1]华北理工大学冶金与能源学院,河北唐山063210 [2]北京科技大学材料科学与工程学院,北京100083

出　　处：《哈尔滨工程大学学报》2022年第10期1478-1482,共5页Journal of Harbin Engineering University

基　　金：国家自然科学基金项目(52074028,51811530016)。

摘　　要：为了解决传统调质热处理工艺获得材料屈强比较高的问题,本文研究了船用高强韧钢在一次淬火+两相区二次淬火+回火过程中的组织转变及其对力学性能与屈强比的影响。通过扫描电镜与高温共聚焦金相显微镜对高强韧钢热处理过程中的组织转变进行观察与分析,并结合力学性能测试分析组织转变对力学性能及屈强比的影响。结果表明:随二次淬火温度的升高,高强韧钢的屈服强度与抗拉强度升高且屈强比升高,高强韧钢热处理态组织为铁素体+回火板条马氏体。高强韧钢在二次加热保温时,一次淬火形成的马氏体板条界促进奥氏体形核从而细化晶粒,提高了强度与低温韧性,屈服强度均高于800 MPa,-50℃冲击功均高于200 J;同时,两相区二次加热时产生了软相铁素体,并在后续二次淬火及回火过程中保持稳定,降低了屈强比,最低可达0.92。合理的二次淬火热处理工艺可以在保证强韧性的前提下获得较低的屈强比。To solve the problem of high yield strength of materials obtained by traditional quenching and tempering heat treatment process, we studied the structural transformation of high-toughness marine steel during primary quenching, secondary quenching in the two-phase region, and the tempering processes and its effect on mechanical properties and yield ratio. The structural transformation of the high-toughness steel during heat treatment was observed and analyzed by using a scanning electron microscope and a high-temperature metallography microscope. The influence of microstructure transformation on mechanical properties and yield ratio was analyzed by conducting a mechanical property test. Results show that with the increase in the secondary quenching temperature, the yield strength, tensile strength, and yield ratio of the high-toughness steel increase, and the heat-treated microstructure of high-toughness steel after heat treatment is composed of ferrite and tempered lath martensite. During secondary heating and heat preservation of high-toughness steel, the martensite lath boundary formed during primary quenching promotes austenite nucleation and improves the strength and low-temperature toughness of high-toughness steel. The yield strength is higher than 800 MPa, and the impact energy at-50 ℃ is higher than 200 J. Soft-phase ferrite is produced during the secondary heating in the two-phase region, which remains stable during the subsequent secondary quenching and tempering, and reduces the yield ratio to 0.92 at the lowest. The reasonable secondary quenching heat treatment process can obtain lower yield strength ratio on the premise of ensuring strength and toughness.

关 键 词：船用高强韧钢 二次淬火 力学性能 屈强比 高温金相 组织转变 铁素体 回火板条马氏体 

分 类 号：TG156.31[金属学及工艺—热处理]