The effect of a vacuum ( approximately 10/sup -6/ torr) on the low-cycle fatigue life (25%, 50%, 75%, and 95% drop in load) of 10Sn90Pb and 63Sn37Pb solder joints tested in shear was investigated in total strain control (by Delta gamma /sub t/=0.006 to 0.5, nu =0.1 Hz ramp cycling) at 300 K. The influence of a grease coating was also determined for the 63Sn37Pb alloy for Delta gamma /sub t/=0.07 to 0.8. No clear effect of vacuum occurred for the strain range considered. However, the grease coating improved fatigue life. Possible explanations for the observed effects are given, including chemical reaction with the specimen surface, i.e. a Rhebinder effect; a crack-filling effect leading to a decrease in the stress intensity factor; and a reduction in friction along the sliding crack surfaces giving less debris and thereby a lower tensile stress at the crack tip.
展开▼
机译：研究了真空（大约10 / sup -6 / torr）对在剪切中测试的10Sn90Pb和63Sn37Pb焊点的低周疲劳寿命（载荷下降25％，50％，75％和95％）的影响。在300 K时进行总应变控制（通过Deltaγ/ sub t / = 0.006到0.5，nu = 0.1 Hz斜坡循环）。还确定了63Sn37Pb合金的润滑脂涂层对Deltaγ/ sub t / = 0.07的影响至0.8。对于所考虑的应变范围，没有明显的真空作用发生。但是，润滑脂涂层改善了疲劳寿命。给出了观察到的效果的可能解释，包括与样品表面的化学反应，即Rhebinder效应;裂纹填充效应导致应力强度因子降低;沿滑动裂纹表面的摩擦减小，从而减少了碎屑，从而降低了裂纹尖端处的拉应力。
展开▼
