1800MPa级低合金超高强度工程机械用钢显微组织与力学性能  

Microstructure and Mechanical Property of 1800 MPa Grade Low Alloyed Ultra-High Strength Steel for Engineering Machinery

作　　者：刘爽[1,2] 唐广波[2] 李激光[1] 孙浩源[1,2] 李斌[1,2] 

机构地区：[1]辽宁科技大学材料与冶金学院,辽宁鞍山114000 [2]钢铁研究总院特殊钢研究所,北京100081

出　　处：《钢铁》2014年第1期79-84,共6页Iron and Steel

摘　　要：设计了一种新型的超高强度工程机械用钢,在中试轧机上进行了不同工艺模拟轧制,对比研究了工艺1(80%变形量+直接淬火+250℃回火)、工艺2(90%变形量+层流冷却快冷至650℃/1h+空冷+250℃回火)和工艺3(90%变形量+空冷至650℃/1h+空冷+250℃回火)3种不同控轧控冷工艺对试验用钢的显微组织和力学性能的影响。结果表明:工艺1条件下试验钢的抗拉、屈服强度最高,塑韧性最好,分别可达到1816,1473MPa,伸长率为9.5%,断面收缩率为45%,室温冲击功为28J,-40℃冲击功为21J,硬度值达到50HRC,认为获得的是板条马氏体+残余奥氏体的复相组织和析出的复合微合金碳化物、ε-碳化物强韧化机制的综合作用;工艺2,3分别得到的是板条马氏体+块状贝氏体+残余奥氏体、板条马氏体+针状铁素体+片层状珠光体+残余奥氏体,力学性能下降明显;第二相析出物主要是Nb,V,Ti的复合析出颗粒。A novel 1800MPa grade low alloyed ultra-high strength steel for engineering machinery was designed and its hot rolling was simulated on a pilot hot rolling mill. Effect of different processes, such as process 1 （deformation of 80% ＋ direct-quenching ＋ tempering at 250℃）, process 2 （deformation of 90% ＋ laminar cooling to 650℃/1 h ＋ air-cooled ＋ tempering at 250℃） and process 3 （deformation of 90% ＋ air-cooled to 650℃/1 h ＋ air-cooled ＋ tempering at 250℃）, on the microstructure and mechanical properties were investigated. The results indicate that the sample of process 1 has a maximum tensile strength of 1816MPa and yield strength of 1473MPa with elongation of 13 percent and reduction of area of 45 percent, the impact energy of room temperature and -40℃（KV2） is 28J and 21J respectively, and the hardness value is 50HRC. It might be from the comprehensive effect of strengthening mechanisms due to the lath martensite＋retained austenite, composite micro-alloy carbide and ε-carbide precipitation. Multi-phase microstructure involving lath martensite＋upper bainite＋retained austenite, lath martensite＋acicular ferrite＋lamellar pearlite＋retained austenite can be obtained by the processes 2 and 3 respectively, and the mechanical properties dramatic decline. The second phase precipitation composite particles are precipitated with Nb,V,Ti.

关 键 词：超高强度工程机械用钢 热轧 碳化物 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]