Rust on Stainless Steel Weld

[sahavas]

Hi,

It has been observed on all weld joints were corroded with rust, but components dont have any rust. can any one answer me the reason why weld joints have only corrosion not on base metal?

Pipe : A312 TP 316 L
Filler wire : ER316L
Weld Type : Butt weld

 

[kingnero]

What is the medium in the pipes?

 

[weldstan]

Possibly using carbon steel brushes or contaminated stainless steel brushes or other contaminated equipment to clean the components or prepare the bevels. I assume that rusting is on the OD surface. Sensitization in the HAZ could be another cause. High ferrite content in the filler metal could also contribute. Note that while the components were most probably pickled and passivated, the weld most likely were not. Restoration may well be accomplished by a number of means - review ASTM A-380.

 

[Ron]

Your filler material is likely closer in chemistry to mild steel than stainless steel.

 

[weldstan]

Another potential cause/contributer is poor inert gas shielding coupled with high heat input or high interpass temperatures resulting in heavy heat tint on the weld.

 

[Duwe6]

Lack of passivation. It is fairly common, as most s/s weld caps are left 'as-welded' and can be 'active' and develop a thick patina of rust over time.