Multiaxial Low Cycle Fatigue of 63Sn-37Pb Solder

This paper describes the tension-torsion low cycle fatigue (LCF) of 63Sn-37Pb solder tube specimens. Tension-torsion LCF tests were carried out at the strain rate of 0.5%/s, and suitability of strain and stress parameters for correlating multiaxial LCF lives was discussed. The Mises' strain, the maximum principal strain and the equivalent strain based on crack opening displacement are appropriate for the data correlation, but no stress parameter exists for correlating the multiaxial LCF within a factor of two scatter band. The Mises' stress gives a relatively small scatter of the data. In the tension tests, main cracks were propagated in the direction normal to the maximum principal strain, whereas they propagated in the principal shear direction in the torsion tests. The transition of crack propagation direction was found at the principal strain ratio of -0.54--0.64, where the principal strain ratio is defined as the ratio of the minimum principal strain to the maximum principal strain.