压铸镁合金腐蚀疲劳性能的研究

研究了压铸镁合金AM50HP和AZ91HP在大气和模拟海水(3.5% NaCl溶液)环境中的疲劳行为.结果表明:压铸镁合金疲劳裂纹萌生于试样表面或近表面的铸造缺陷处;压铸镁合金AM50HP和AZ91HP在大气环境中具有疲劳极限,其值分别约为100MPa和90MPa,而在模拟海水环境中该两种压铸镁合金均不存在疲劳极限;模拟海水严重恶化压铸镁合金AM50HP和AZ91HP的疲劳性能,并且随着施加载荷的降低,影响加剧;特别地,研究发现模拟海水对压铸AM50HP疲劳性能的恶化程度较压铸镁合金AZ91HP更为严重,且这种影响趋势与该两种镁合金的机械化学性能相一致.

Corrosion Fatigue of Die-Cast Magnesium Alloys

The fatigue properties of die-cast magnesium alloys AM50HP and AZ91HP were determined in ambient air and in 3.5% sodium chloride solution,respectively.It is found that fatigue cracks initiate from the casting pores within the specimen and near the surface in both environments depending on the relative pore size,and the S-N curves of both alloys are steeper in corrosive environment than in ambient air.Both die-cast magnesium alloys do not have endurance limits in 3.5% NaCl solution,whereas endurance limits could be detected in ambient air,which are about 90MPa and 100MPa for AZ91HP and AM50HP respectively.The die-cast magnesium alloy AM50HP shows a higher sensitivity to the action of 3.5% NaCl solution in comparison with AZ91HP,and the corrosion fatigue behaviour of both die-cast magnesium alloys correlates with their mechanochemical behaviour.The latter was studied by the polarization measurements of the dissolution rate of strained magnesium alloys.