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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 new type of ultra-high strength steel for engineering machinery was designed and simulated by different processes on the pilot mill. The effects of process 1 (80% deformation + direct quenching + 250 ℃ tempering), 2 90% deformation + laminar cooling to 650 ℃ / 1h + air cooling + 250 ℃ tempering) and Process 3 (90% deformation + air cooling to 650 ℃ / 1h + air cooling + 250 ℃ tempering) Effect of Cold Process on Microstructure and Mechanical Properties of Test Steels. The results show that the tensile strength and yield strength of the test steel under the first condition are the highest, the plasticity and toughness are the best, reaching 1816 and 1473MPa respectively, the elongation is 9.5%, the reduction of area is 45% and the room temperature impact energy is 28J, The impact energy at 40 ℃ is 21J, the hardness reaches 50HRC, and it is considered that the composite phase of lath martensite + retained austenite and the composite microalloyed carbides and ε-carbide toughening mechanism are obtained. ; The lath martensite + massive bainite + retained austenite, lath martensite + acicular ferrite + lamellar pearlite + retained austenite are obtained respectively in the processes 2 and 3, and the mechanical The performance of the obvious drop; the second phase precipitates are mainly Nb, V, Ti composite precipitation particles.