When temporary steel backing is used for aluminum groove welds, the AWS D1.2 Aluminum Welding Code requires austenitic stainless steel to be used. In our application we will be MIG welding 1/4” thick aluminum partial joint penetration groove welds with a root gap not to exceed 1/32” and a 1/16“ root face. What problems might we encounter if we just use clean low carbon steel for temporary backing? Can anyone refer me to research on using different types of steel for temporary backing for aluminum welds?