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采用EHF-EM200K2-070-1A型液压伺服疲劳试验机对轧制变形MB8镁合金室温高周疲劳性能进行了研究。结果表明:在拉-拉疲劳应力比为R=0.1,循环基数为1×10~7条件下,MB8镁合金的疲劳强度为69.41 MPa,相当于其抗拉强度的30%左右;MB8镁合金的疲劳裂纹萌生于试样表面,裂纹扩展区由小的平面状断面组成,并有少量二次裂纹。疲劳断口上没有明显的疲劳辉纹,MB8镁合金疲劳断口在裂纹萌生区塑性变形很小,在裂纹扩展区呈现出多个小平面以及撕裂棱组成的准解理断裂特征。在最终断裂区断口上可观察到韧窝存在,呈现出韧性断裂特征。
EHF-EM200K2-070-1A hydraulic servo fatigue testing machine was used to study the high-temperature fatigue properties of MB8 magnesium alloy under room temperature. The results show that the fatigue strength of MB8 magnesium alloy is 69.41 MPa, corresponding to about 30% of the tensile strength of the MB8 magnesium alloy under the condition of R = 0.1 and 1 × 10-7. Of the fatigue crack initiation on the surface of the specimen, the crack propagation zone consists of small planar cross-section composition, and a small amount of secondary cracks. There is no obvious fatigue fringe on the fatigue fracture. The fatigue fracture of MB8 magnesium alloy shows little plastic deformation in the crack initiation area, and exhibits many quasi-cleavage characteristics of multiple facets and tearing edges in the crack propagation area. In the final fracture zone can be observed on the presence of dimples, showing a ductile fracture characteristics.