高强度模具钢动态断裂性能的研究

A Study of Dynamic Fracture Behaviour of High Strength Die Steels

测定了A_2、D2两种高强度模具钢在不同应变速率下的动态起裂韧性K_(1d)值,并得到了它的下限值K_(1m)~c。用扫描电镜对不同应变速率下的断口形貌进行了验证分析,得到了与静态加载不相同的新结果。提出了以K_(1m)~c或临界应力强度因子变化率[K_1]~c来评定动态断裂特性的准则,对高强度模具的使用和安全设计有重要的参考价值。

In this paper, the dynamic fracture initiation toughness K_(?) of high strength die steel A_2, D_2 over a wide range of loading rates has been determined, and its lowest value K_(1m)~c has also been obtained, The fractomicrographs at various loading rates have been investigated by SEM. The interesting results show that the microstrusture of the crack tip zone under dynamic loading is quite different from that under static loading. It is suggested that K_(1m)~c and its corresponding critical stress intensity factor rate [K_1]~c can be used as a criterion, which is available for reference in design and application, to evaluate the fracture behaviour.