Two-level step multiaxial fatigue tests were conducted to investigate the crack growth behavior and damage accumulation of 30CrMnSiA steel. When the first load step (50% of the fatigue failure life) is completed, main cracks of specimens have entered the stage Ⅱ propagation. The cracks gradually turn direction to propagate along the maximum normal stress planes of load step 2 under the second load step. The damage accumulation is mainly affected by the angle between the maximum normal stress planes of the two-level step loadings and the crack propagation length along the depth direction, it will also lead to large error of fatigue life prediction by the commonly used damage accumulation models.

通过两级多轴疲劳试验研究了30CrMnSiA钢的裂纹扩展行为和损伤累积。当第一个载荷步（疲劳失效寿命的 50%）完成时，试件的主要裂纹已进入Ⅱ阶段扩展。在第二个载荷步下，裂纹逐渐转向沿载荷步 2 的最大法向应力平面扩展。损伤累积主要受两级阶跃加载最大法向应力平面夹角与裂纹沿深度方向扩展长度的影响，也会导致常用的损伤累积模型疲劳寿命预测误差较大.