Dissimilar Metals

Many thanks to Chris W.

Found it in Volume 4 of the AWS Welding Handbook 2nd Ed. Chapter 12 Dissimilar Metals.The AWs recommends the use of transition piece or buttering. The AWS also cited special consideration, discusses the characteristics of thermal expansion and other design requirements. for joining dissimilar metals.

As Chris pointed out, the difference in coef. of thermal expansion (alpha) will introduce a residual stress at the weld joint. Unfortunately B31.3 is silent about this but fortunately AWS says relate that damn thing using the strain and the thermal expnasion stress and compare it againts the allowable stress range (how stupid of me for missing it.). I did and was able to to figure out if the joint is over stressed or not.

Basic theory, simple math plus and a lil help from our friend in the pipingdesign.com forum did it. Now all i have to do is qualify the welding - be glad to share it you guys if interested. i mean the basic equation and the welding procedure speciifcation. Received on Thu Jun 14 03:27:00 2001