Fracture Mode of <i>E</i>50 Solder Notched Bars at Low Temperature

Abstract

Fracture tests were performed on 20 notched bars fabricated from E50 solder at low temperature (-47°C~-43°C). The effect of notch radius, r, and notch depth, d, on fracture mode of E50 solder was studied. The experimental results demonstrate that cracks initiate at the center of notch section and the notched bars fracture at the notch section at low temperature. The fracture mode is cleavage fracture and the fracture sections are coarse. Specimens with a sharper notch radius (a smaller r) and a larger notch depth (a smaller d) show poor ductility, but high fracture strength. The stress-strain curve of E50 solder tested on standard specimen at low temperature (-47°C~-43°C) exhibits the character of yielding, hardening and necking. The ratio of ultimate strength to yield strength, σu/σy, and the ductility, δ5, at low temperature meet with the requirement in plastic design for structural steel.