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对20g钢的高温断裂行为进行了试验研究：高温断裂韧性的温度和应变速率效应；裂纹扩展速率da／dt与C*积分的相关性。试验结果表明，断裂韧性Ji值随应变速率的增大而有较大幅度的降低；在同一应变速率下，温度400℃时的Ji值小于500℃时的。在C*=10-4～10-1J/mm2·min的负我强度下，da／dt与C*积分相关；C*积分可作为裂纹扩展速率的控制参量。温度400℃下裂纹扩展速率da／dt明显地大于500℃下的da／dt。因此，在温度400℃左右时更应尽量避免超载。
The high temperature fracture behavior of 20g steel was studied: the temperature and strain rate effect of high temperature fracture toughness; the correlation between crack propagation rate da / dt and C * integral. The experimental results show that the fracture toughness Ji value decreases with the increase of strain rate, and the Ji value at 400 ℃ is less than 500 ℃ at the same strain rate. The da / dt is related to the C * integral at a negative I intensity of C * = 10-4 to 10-1 J / mm2 · min; the C * integral can be used as a control parameter for the crack propagation rate. The crack growth rate da / dt at a temperature of 400 ° C is clearly greater than the da / dt at 500 ° C. Therefore, the temperature should be about 400 ℃ to avoid overloading.