Root pass problems

By zieglejo Date 12-17-2007 16:24

I am trying to get some of my welders certified in GMAW-S, but we keep getting the roots to crack. The material is all A36; 3/8" base metal, 1/4" backing, 45 deg. included angle; root and face guided bends. Some of the root bends are perfect, some crack badly. Any suggestions?

Zieglejo

By Lawrence (*****)

Date 12-17-2007 20:31

My suggestion would be to ditch the backing strips.

3/8 with short circuit and a backing strip is poor engineering anyhow... It can be done, but it can be done better with spray transfer flat and horizontal or FCAW in all positions

Without a backing strip you can go open root with your typical included angles for the bevel, a 1/8 inch root opening in 1G,2G and 4G and a 3/32 root opening for 3G... Make your root faces a consistant 1/16th....

If your working to D1.1 it will qualify for both open root and with backing. If your short circuiting you will need to qualify the procedure anyhow, so you might as well make it go a little further.

Thats my 02 cents