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在高温下施以恒应变拉伸的模拟焊接热循环的结果表明,1350～1450℃是晶间液化引起脆性断裂的敏感温度区;900～1000℃是不均匀再结晶引起低塑性断裂的敏感温度区。在高温应变条件下,初始阶段,裂纹优先在基体界面或晶界液化的夹杂物处萌生;形变后期,裂纹大量在再结晶晶界处萌生。本文建立了断裂模型,可用以解释高温低塑性断裂的微观过程.
Simulated welding heat cycles at constant strain at high temperature show that the temperature range from 1350 to 1450 ℃ is the sensitive temperature region where the intergranular liquefaction can cause brittle fracture and the temperature range from 900 ℃ to 1000 ℃ is the sensitive temperature region with low plasticity due to inhomogeneous recrystallization. Under the conditions of high temperature and strain, in the initial stage, the cracks preferentially initiate at the interface of the matrix or inclusions liquefied at the grain boundaries. In the late stage of deformation, a great deal of cracks initiate at the recrystallized grain boundaries. In this paper, a fracture model is established, which can be used to explain the microscopic process of high temperature and low plastic fracture.