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对一种新型高强韧微变形钢(GDL-1)的断裂韧性进行了研究,分析了七种不同热处理状态的JR阻力曲线。结果表明,试验钢在经空冷250℃-300℃回火后的裂纹扩展阻力较大,J1C=0.1415-0.1513(MPa.m)、AK=97-120.5(J),其断裂韧性和冲击韧性优于其它状态。扫描电镜和透射电镜分析表明,空冷后新型高强韧GDL-1钢的显微组织为窄束状贝氏体+马氏体和部分残余奥氏体复合组织,残余奥氏体以薄膜形态分割贝氏体板条而形成超细化亚单元,增加了材料的微观塑性。此外,低温回火改善钢的韧性,并使残余奥氏体的稳定性提高,从而使该钢在空冷250℃-300℃回火后具有良好的冲击韧性和断裂韧性。
The fracture toughness of a new type of high toughness micro-deformable steel (GDL-1) was studied and JR resistance curves of seven different heat treatment conditions were analyzed. The results show that the crack propagation resistance of the test steel after tempering at 250 ℃ -300 ℃ by air cooling is large, with the fracture toughness and impact toughness being excellent (J1C = 0.1415-0.1513 (MPa.m), AK = 97-120.5 (J) In other states. Scanning electron microscopy and transmission electron microscopy analysis showed that the microstructure of the new high strength and toughness GDL-1 steel after air cooling is a narrow bundle of bainite + martensite and some residual austenite composite microstructure, residual austenite thin film morphology The martensite slab forms a superfine subunit, increasing the micro plasticity of the material. In addition, tempering at low temperature improves the toughness of the steel and increases the stability of the retained austenite, so that the steel has good impact toughness and fracture toughness after being air-cooled at a temperature of 250-300 ° C.