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.