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采用J积分方法研究了SA508-Ⅲ钢不同加载速率下的断裂韧性,探讨了不同加载速率钢的断裂行为。结果表明,SA508-Ⅲ钢的断裂韧性随加载速率的升高而增加。随加载速率升高,SA508-Ⅲ钢裂纹尖端区域达到临界应变率所需应力功增加,钢断裂前所吸收的能量增加,因此钢断裂韧性增加。同时,随加载速率升高,主裂纹沿碳化物与基体的界面启裂和扩展时间减少,位错密度增加,引起裂纹尖端应力应变集中,增加了钢的变形抗力,因此钢的断裂韧性增加。
The fracture toughness of SA508-Ⅲ steel under different loading rates was studied by J-integral method, and the fracture behavior of steels with different loading rates was discussed. The results show that the fracture toughness of SA508-Ⅲ steel increases with the increase of loading rate. With the increase of loading rate, the stress energy required to reach the critical strain rate in the crack tip region of SA508-Ⅲ steel increases, and the energy absorbed before fracture increases, so the fracture toughness of steel increases. At the same time, as the loading rate increases, the crack initiation and propagation time along the interface between the carbides and the matrix decreases, the dislocation density increases, stress and strain at the tip of the crack increase, and the deformation resistance of the steel increases. Therefore, the fracture toughness of the steel increases.