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为研究AZ31B镁合金抵抗裂纹扩展能力,对其开展平面应变断裂韧度试验,同时采用红外热像法记录了试样表面断裂过程的温度演化。结果表明,AZ31B镁合金的断裂韧度为15.33~16.07 MPa·m1/2,断裂过程中裂纹尖端附近的温度演化分为三个阶段:初始稳定阶段、温度升高阶段和最终稳定阶段。温度演化是热弹性效应、裂纹尖端塑性耗散和热传递的综合作用,温度升高的热量来自于裂纹扩展过程中尖端塑性区的能量耗散。材料的断裂韧度和温升有很大关系,断裂韧度越大,温升越高。
In order to study the resistance to crack propagation of AZ31B magnesium alloy, the plane strain fracture toughness test was carried out. The temperature evolution of the fracture surface was recorded by infrared thermography. The results show that the fracture toughness of AZ31B magnesium alloy is 15.33 ~ 16.07 MPa · m1 / 2. The temperature evolution near the crack tip in the fracture process is divided into three stages: the initial stabilization stage, the temperature rise stage and the final stabilization stage. The evolution of temperature is the combination of thermoelasticity, plastic dissipation of crack tip and heat transfer. The heat of increasing temperature comes from the dissipation of energy in the tip plastic zone during crack propagation. Fracture toughness and temperature have a great relationship, the greater the fracture toughness, the higher the temperature rise.