ASTM A653 Grade 50 is not a listed steel in AWS D1.3 as an approved weldable steel. Why not?
ASTM A653 SS Grade 50 is not in the AWS D1.3 list of approved steels because the phosphorus content for Classes 1, 2, and 4 is 0.20%. The AWS Committee tends to limit phosphorus in prequalified steel grades to 0.05%. Rather than designate only ASTM A653 SS Grade 50 Class 3 as acceptable, the AWS Committee did not list Grade 50 steels. Class 3 material would be weldable, but would require qualification on the part of the user.
