stress relieve 4130 tube
stress relieve 4130 tube
(OP)
Ive built a full roll cage in an off-road truck using 4130 1 3/4 x .120 wall tube. This is the first time ive used 4130 as opposed to mild steel. Ive mig welded all joints and everything seems to have come out well. This cage is tied to the frame and will be subjected to a lot of flex.
Do I need to stress relieve these welds?
Will the weld joints be prone to cracking?
If so, what methhod is best to use for stress relieving the joints?
Do I need to stress relieve these welds?
Will the weld joints be prone to cracking?
If so, what methhod is best to use for stress relieving the joints?





RE: stress relieve 4130 tube
The area of concern isn't the weld metal or base metal, but the heat-affected zones(HAZ) right alongside the welds. They will likely be harder and more brittle unless you do the HT.
RE: stress relieve 4130 tube
RE: stress relieve 4130 tube
If you've got to keep those joints at 1100 for 30 minutes, it's going to take a long time to do a whole cage.
RE: stress relieve 4130 tube
RE: stress relieve 4130 tube
What you can do is use preheat--about 300 deg. F should work.
The aim is to slow down the rate of cooling thru the all-important range of ~1,250-1100 deg F. That's where the hard HAZ are generated.
RE: stress relieve 4130 tube
Good day
Gerald Austin
Iuka, Mississippi
http://www.weldinginspectionsvcs.com
RE: stress relieve 4130 tube
If the welding process were oxy-fuel, then no preheat or PWHT would be required, because the entire weld area is heated very high, thus greatly reducing the quench/cooling rate.
TIG doesn't heat the surrounding base metal as high, but I think the cooling rate is slower than with MIG, the process that was used. For a structure loaded with cyclic stresses, *I* would do something other than MIG weld it cold and then leave it.
RE: stress relieve 4130 tube
RE: stress relieve 4130 tube
RE: stress relieve 4130 tube
RE: stress relieve 4130 tube
Then use a torch to *slowly* heat the area up to ~1,100 deg F. I know I said 30 min. before, but even a few seconds at 1,100 will help a lot. But DO NOT heat it over 1,300 deg!
You'll need someone to take the temp. readings while you torch it.
If you can find some nichrome, etc. wire you could also wrap it around the joints and use your welding machine to supply the heat.