Defining a Critical Weld Dilution to Avoid Solidification Cracking in Aluminum

Abstract

Al-Mg-Si alloys are known to be highly susceptible to solidification cracking except when using an appropriate filler metal (e.g., 4043 or 5356), although the amount of dilution required to avoid cracking has never been a well-defined quantity. The aim of the present study is to determine a relationship between filler metal dilution, local strain rate conditions, and cracking susceptibility. Making use of the controlled tensile weldability (CTW) test and local strain extensometer measurements, a boundary has been established between crack and no-crack conditions for different local strain rates and dilution amounts, holding all other welding parameters constant. This boundary, presented in the form of a critical strain rate-dilution map, defines the critical amount of 4043 filler metal required to avoid solidification cracking when arc welding 6060 aluminum, depending upon local strain rate.