BHW60钢的临界空穴扩张状态与相关的断裂韧性

CRITICAL VOID-GROWTH STATE AND RELATED FRACTURE TOUGHNESS IN BHW60 STEEL

用扫瞄电镜在拉伸试样断口心部,测量了BHW60钢在20,-60,-100和-140℃下的临界空穴扩张比R_e/R_o,研究了它与宏观断裂韧性V_GC的关系以及热处理状态的影响结果表明:(1)同一温度下R_e/R_o的测量值大致遵循正态概率分布;(2)R_e/R_o随着温度降低直线减小; (3)R_e/R_o与V_GC的关系为V_GC=Cln(R_e/R_o),其中C≈3.5,与R—T空穴扩张模型符合得较好。

The critical void-grwoth ratio, R_c/ R_o, was measured quantitatively under SEM to the core of fracture surface of smooth and notched tensile specimens for BHW60 steel at 20, -60, -100 and -140℃. Correlation between R_c/ R_0 and macroscopic fracture toughness, V_(GC), as well as the effect of heat treated condition upon them were investigated. Results show that the R_c/ R_0 values are approximately obedient to normal probability dis- tribution at the same temperature, decrease linearly with the decrease of temperature and are related to V_(GC) as: V(GC)= Cln(R_c/ R_0), where C=3.5. This expression seems to be in good agreement with the R-T model of void-grwoth and the coefficient C is insensitive to temper- ature and heat treated condition.