GMAW for Ferritic 430
GMAW for Ferritic 430
(OP)
I am facing a problem of regular breakage in welding of ferritic 430 and 409 grade.Material is actually strip of 4to 6mm thickness.The strip get broke down during processing on CR mill.
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RE: GMAW for Ferritic 430
1. Was the MIG welding performed in one pass or multi-pass for joining the strip sections?
2. What was the filler metal, if any?
Ferritic stainless steels can form coarse grains in the weld HAZ and can result in significant loss of toughness, especially during forming operations
RE: GMAW for Ferritic 430
RE: GMAW for Ferritic 430
The 308 filler metal is acceptable for this application. Inconel will not help because the problem is most likely in the base metal heat affected zone.
Several Recommendations, pending the results of your analysis;
1. You need to reduce heat input for the multipass welds - keep the interpass temperature below 575 deg F. Stick with multi-pass welds.
I would try the following post weld heat treatment - locally heat the weld zone to about 1450 deg F for about 10 minutes. This short PWHT should restore ductility to the weld HAZ.
Grind the weld cap flush to reduce any stress concentration prior to forming.
RE: GMAW for Ferritic 430
You need to:
a)switch to 439, a stabilized 430 or
b)anneal the weld
Michael McGuire
http://stainlesssteelforengineers.blogspot.com/
RE: GMAW for Ferritic 430
The trick is to temper the welds. You don't need full anneal, but a temper is esential. Check some hardnesses. The welds should pass bend tests.
Due to the matersite that forms you get fine grained welds. 439 is a problem becuase the welds are very coarse grained.
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Corrosion never sleeps, but it can be managed.
http://www.trenttube.com/Trent/tech_form.htm
RE: GMAW for Ferritic 430
When you temper the welds is the idea to do it at a low enough temp that you don't sensitize?
Michael McGuire
http://stainlesssteelforengineers.blogspot.com/