Effects of filler metals and relation between tensile and fatigue strengths

Abstract

The fatigue properties of several kinds of welded aluminum alloys for construction such as Al-Zn-Mg, Al-Mg, and Al-Mg-Si systems were investigated. The experiments were conducted on the effects of filler metals on fatigue properties of welds and the relation between tensile and fatigue strengths of the alloys.The following results were obtained.(1) Higher fatigue strengths were obtained when Al-Mg alloys were welded with the filler metal of Al-Mg system having the same content or higher Mg content than the parent metal.(2) The proper filler metal for Al-1.0% Mg-0.6% Si alloy was Al-4.5-5.0% Mg alloy containing a considerable amount of Mn.(3) Al-Zn-Mg alloys welded with the filler of the same system were higher in fatigue strength and more insensitive to notch or source of stress concentration than with the filler of Al-Mg or Al-Si system.(4) The relation between fatigue and tensile strengths of welds was indentical with that of the parent material in the range of tensile strength up to 15kg/mm2. However, when the strength was above 15kg/mm2, the fatigue strength of welds showed a different behavior from that of mother plate. This would be interpreted by notch sensitivity of welded parts.