本文用光学和电子显微镜研究了碳含量在0.39%～0.42%间变化对GC-4型钢显微组织(190℃等温、260℃回火)的影响。讨论了显微组织与力学性能间的关系。结果表明,碳含量低于0.40%的钢比碳含量大于0.40%的钢具有较好的强韧性配合。随着碳含量的进一步增加,抗拉强度增加幅度不大,而屈服强度反而有下降趋势。为了获得较好的强韧性配合,应将碳含量控制在0.40%以内。

The effect of carbon content within 0.38% to 0.40% on the microstructure of GC-4 ultra-high strength steels after isothermal transformation and low temperature tempering has been studied in the present investigation,and the relationship between the microstructure and mechanical properties of the steels has been discussed.The results show that the steels with the carbon content lower than 0.40% have better strength-toughness conbinations than those with the carbon content greater than 0.40%.It has been found that with the further increment of carbon content the ultimate tensile strength increased slightly,but the yield strength of the steel showed the decreasing trend.Therefore,in order to obtain a better conbination of strength and toughness,it is reasonable that the carbon content of GC-4 steel should be controlled below 0.40%.