下贝氏体对GD钢力学性能的影响

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.

The Effects of Lower Bainite on the Mechanical Properties of Type GD Steel

The morphology of microstructure and the amount of lower bainite of type GD steel with different silicon contents after isothermal heat treatment have been investigated. The effects of lower bainite on the mechanical properties of type GD steel have been studied. Results show that the amounts of silicon are responsible for the amount and microstructure of Jower bainite. When the amount of silicon of type GD steel is nearly 0 (type GD3), the lower bainite of the duplex microstructure appears as typical lower bainite. When the amount of silicon of type GD steel is 1.82% in weight (type GD4), the lower bainite appears as pseudo-lower bainite. The duplex microstructure of type GD4 steel exhibits the best strength-toughness combination. After isothermal heat treatment and a comparison of steel type GD4 with steel type GD3, it is found that the bending flexibility of the former is 1.9 times that of the latter, the impact toughness 2,7 times and the fracture toughness 8.29 MPa.m1/2 greater.