【摘要】 通过红外热像仪,记录5A06铝合金疲劳裂纹沿平行轧制方向和垂直轧制方向扩展过程中的温度演化,并对两个方向疲劳裂纹扩展过程中的各向异性进行研究。结果表明,两个方向试件表面的温度演化具有相同的规律,其温度演化均分为3个阶段:初始的缓慢温升阶段,试件断裂时的急剧温升阶段,试件断裂后的自然降温阶段。施加不同应力时,沿平行轧制方向扩展的试件,其断裂温升值分别为5.75,3.02,2.77℃;沿垂直轧制方向扩展的试件,其断裂温升值分别为10.73,5.03,3.53℃。在相同应力下,沿平行轧制方向扩展的试件,其裂纹扩展得更快;沿垂直轧制方向扩展的试件,其断裂温升值更高。裂纹扩展相同的距离时,垂直轧向的试件受到的阻力更大,耗散的能量更多,扩展得较慢,这与红外热像仪所观察的垂直轧向的温升值要高于平行轧向结果具有很好的一致性。由于裂纹扩展速率的计算较复杂,因此可以通过红外热像仪来间接观测铝合金疲劳裂纹扩展过程中的各向异性。更多还原

【Abstract】 This article uses the infrared thermal imager to record the temperature evolution during the process of fatigue crack propagation of 5A06 aluminum alloy parallel with and perpendicular to the rolling direction.The anisotropy during the process of fatigue crack propagation in two directions has been researched.The temperature evolution during fatigue crack propagation process shows three stages:initial slow temperature rise stage,rapid temperature rise stage,and finial temperature decline stage.Under different stresses,the fracture temperature increase value in parallel with rolling direction is 5.75 ℃,3.02 ℃ and 2.77 ℃,respectively,and that in perpendicular to the rolling direction is 10.73℃,5.03℃ and 3.53℃,respectively.Under the same stress,the fatigue crack propagation rate in parallel rolling direction is higher than that in perpendicular rolling direction,and the fracture temperature in perpendicular rolling direction is higher than that in parallel rolling direction.When the crack extends same distance,samples in transverse direction consume more energy and longer time than in longitudinal direction.The result has a good consistency with the temperature change.The crack propagation rate is difficult to be measured,so the anisotropy during the process of fatigue crack propagation can be indirectly presented by the temperature recorded by infrared thermography.更多还原