welding 4130 and anealing 1

[Picone]

After welding 4130 tubing (for a roll cage), I know a guy, (a very reputable guy) who is dousing it with WD-40. I know you are supposed to anneal a 4130 joint but what does the WD-40 do? He does not anneal the tubing after spraying with WD-40.

Before you say he is doing it wrong, his work stands up to the worst abuse possible. Anyone seen this before?

 

[Rich2001]

Along with the information you obtained on the AWS Forum

http://www.aws.org/cgi-bin/mwf/topic_show.pl?id=4813

4130 is used in the normalized or near normalized condition and does not require heat treatment. In the normalized state the maximum allowable tension stress is 95 ksi. At this value 4130 has good toughness and excellent elongation, useful in a roll cage.

By letting weld joints air cool, the joint becomes normalized. Thin wall tubing normally does not require stress relief. For parts thicker than .120", stress-relieving is recommended and 1,100ºF is the optimum temperature for tubing applications. An Oxy/Acetylene torch with neutral flame can be used. It should be oscillated to avoid hot spots.

I suspect that the tubes are around 1/8" or thinner wall thickness therefore heat treatment, i.e. stress relieving is not required.

 

[sacem1]

The only reason to spray or apply by any other way WD-40 over a weld of ANY kind would be to retard any rust on the just heated part which by reason of the heat has lost the oily protection that most tubes usually carry from the tube manufacturer.

That has nothing to do with a good welding work having been done, it neither enhaces it nor it affects it in other way.

SACEM1

 

[Metalguy]

How soon after he's done welding does he spray? What welding method is he using?

If he uses gas welding he'll probably be OK, but if he uses TIG he (or his customers) might get an unpleasant surprise if the heat of his tubing is near the max. limits of C, Mn, Cr and Mo, especially if he sprays while the joint is still red hot!

 

[Picone]

Rich - Thanks for the reply. You are absolutely right. The tubes are smaller than 1/8" wall...always. Question #1 - What is your source for this information? #2 How do you know the tubes under 1/8" wall will cool to the normalized state? This seems to be the exact reason it doesn't need to be stress relieved. Do you think the effects would be different in TIG as opposed to MIG (as far as cooling to the normalized state)?