本文对不同硅含量的高强韧低合金冷模具钢系列(代号GD钢)进行试验,探讨了GD钢经马氏体-下贝氏体复相处理后,组织中下贝氏体的组织形态和数量及其对GD钢性能的影响.结果表明:改变GD钢的硅含量时,GD钢复相组织中的下贝氏体组织形态和数量也随之改变.当硅含量达到1.82%(wt-%)时,复相组织中下贝氏体呈准下贝氏体形态.马氏体加上约28%(vol-%)的准下贝氏体的复相组织具有最佳的强韧性配合. In this paper, a series of high toughness and low alloy cold die steel with different silicon contents (GD steel) were tested to investigate the microstructure and morphology of the middle and lower bainite in the GD steel after martensite-bainite complex treatment The results show that the morphology and quantity of lower bainite in the complex phase of GD steel also change when the silicon content of GD steel is changed.When the silicon content reaches 1.82% (wt- %), The lower bainite in the complex phase has a quasi-lower bainite morphology, and martensite plus about 28% (vol-%) of the quasi-lower bainite complex has the best combination of toughness .