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研究含混合稀土1%(质量分数)的压铸镁合金AZ91D在应力比r=0.1的高周疲劳性能。组织分析表明,压铸镁合金试样的表面层和心部的显微组织存在差别。室温条件下抗拉强度为185MPa,屈服强度为159MPa,延伸率为1.5%。测试存活率p=50%的p-S-N曲线,结果显示在3.8×105循环周次时的疲劳强度为70MPa,得出在循环周次103～106之间,p=50%时,S与Np的关系式为lgNp=17.85-6.83lgS。在较低的应力下,一些疲劳试样断口出现擦痕,当缺陷较小时,疲劳断口表现为韧窝、撕裂棱、疲劳条带等韧性断口和准解理的混合特征,属于具有较低韧性的材料。
The high-cycle fatigue behavior of die-cast magnesium alloy AZ91D with 1% (mass fraction) mixed rare earth at stress ratio r = 0.1 was studied. Tissue analysis shows that there are differences between the microstructure of the surface layer and the heart of the die-cast magnesium alloy specimen. Tensile strength at room temperature 185MPa, yield strength of 159MPa, elongation of 1.5%. The pSN curve of the test survival rate p = 50% showed that the fatigue strength at the cycle of 3.8 × 105 was 70 MPa, and the relationship between S and Np was obtained at 103 to 106 cycles and at p = 50% The formula is lgNp = 17.85-6.83lgS. At lower stress, some of the fatigue specimens showed scratches on the fracture surface. When the defects were small, the fatigue fracture showed mixed features of tough fracture and quasi-cleavage such as dimples, tear edges and fatigue bands, Tough material.