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以42CrMo钢为研究对象,在Gleeble-1500D热模拟试验机上进行高温拉伸实验,研究了变形温度为900℃、950℃、1 000℃、1050℃、1100℃、1150℃,应变速率为0.01s-1、0.1s-1、1s-1、10s-1条件下的高温变形行为,采用Gleeble Fracture Limit(GFL)方法得到相应的应力、应变参数,基于Normalized Cockcroft&Lathamm损伤模型,计算得到不同变形温度和不同应变速率时的临界损伤值,考虑变形温度和变形速率对临界损伤值的影响引入了Zener-Hollomon参数,得到临界损伤值与lnZ值之间的高温损伤模型。采用扫描电镜对拉伸断口进行断口形貌观察,发现大量韧窝及夹杂物的存在,分析得到该断裂机制为韧性断裂。
Taking 42CrMo steel as the research object, the high-temperature tensile test was carried out on the Gleeble-1500D thermal simulation tester. The deformation temperature was 900 ℃, 950 ℃, 1000 ℃, 1050 ℃, 1100 ℃, 1150 ℃ and the strain rate was 0.01s -1, 0.1s-1, 1s-1 and 10s-1, the corresponding stress and strain parameters were obtained by Gleeble Fracture Limit (GFL) method. Based on the Normalized Cockcroft & Lathamm damage model, different deformation temperatures and The critical damage values at different strain rates, the Zener-Hollomon parameters were taken into account in consideration of the influence of deformation temperature and deformation rate on the critical damage values, and a model of high temperature damage between critical damage values and lnZ values was obtained. Scanning electron microscopy (SEM) was used to observe the fracture surface morphology of the tensile fracture. A large number of dimples and inclusions were found, and the fracture mechanism was found to be ductile fracture.