Compound Fillet Welds making in a WC

[djw2k3]

Hi there,

I have been out of the welding spec game for some time now but have been asked for a genereal weld specification.

Basically I am creating a welded column, flanges 20mm and web 25mm. Overall dimensions are 300x320mm. Parent material is grade S355J2 - so 355MPa yield.

I don't imagine any preheat/post heat is required with the material type and thickness, but my question is about the weld filler material.

The weld throat will be 20mm at least and full penetration, and needs to be equal strength to parent material. Is there any problem with using filler material with a yield strength of 400MPa for all passes, or is it beneficial to used unmatched lower strength filler for root passes to reduce chance of cracking etc.

Any recomendations or references would be greatly appreciated.

Thanks in advance,

Dave

 

[metengr]

No. I would use a weld filler metal with 480 MPa tensile strength requirement and 390 MPa yield strength requirement. Using undermatched (mechanical properties) weld metal to assure a "crack free' weld root deposit is not recommended.

To avoid weld root cracking requires good joint fit up, cleanliness, specified preheat and a weld bead width-to- depth ratio of between 1:1 to 1.4:1. Also a slightly convex weld bead texture is desirable for weld root appearance. Preheat is your key in avoiding cracking in most cases.