Effects of solidified structures in aluminum alloy welds on their mechanical properties Basic studies on solidification mode of welds (2nd report)

• Published in: Journal of Japan Institute of Light Metals Vol. 20; no. 9; pp. 458 - 467
• Main Authors: FUKUI, Toshiyasu, NAMBA, Keizo
• Format: Journal Article
• Language: Japanese
• Published: The Japan Institute of Light Metals 30.09.1970
• ISSN: 0451-5994; 1880-8018
• DOI: 10.2464/jilm.20.458

This paper discussed the effects of solidified structures of aluminum alloy welds on their several mechanical properties. Experiments were conducted for the tests of such as tensile, bending, impact and hardness on the same specimens as those reported in the previous paper. The properties of such as tensile, bending, impact and hardness were remarkably decreased with the growth of dendrite cells. There was a linear relationship between the tensile strength and reciprocal of square root of dendrite cell size as predicted from Petch's equation. Concentrations of solutes such as Mg, Zn, Fe and Si in dendrite cell matrix were decreased with the growth of dendrite cells. However, they were nearly homogenized by the postweld heat treatment, except for the cases of Fe and Si. The tendency of decreasing mechanical properties with the increase of heat input or growth of dendrite cells was scarcely affected by homogenizing, except for hardness property, although the mechanical properties in general were remarkably changed by homogenizing. Quench-sensibility or age-hardenability of Al-Zn-Mg alloy welds was scarcely affected by the heat input in these experiments, though it was generally considered to partly depend upon the solidification rate. It was concluded that the mechanical properties of welds were affected by the dendrite cell size, solute concentration, distribution of secondary phase, and grain structure. In particular, the effects of the former two factors were significant among them; in addition, the effects of impurities such as Fe and Si were not negligible.