Rewelding on 4140 material Rotek slew bearing - previously welded
Rewelding on 4140 material Rotek slew bearing - previously welded
(OP)
What considerations should be looked at when rewelding on a 4140 4' dia. steel slew bearing that is being relocated from one drill rig to another?
Concerned that the heat effected zone on the initial weld on the bearing metal has made the area too hard now. Will be testing its brinell hardness soon. Are there limits on the hardness for re-welding?
I am not a welding engineer and need some advise.
Thank you
Concerned that the heat effected zone on the initial weld on the bearing metal has made the area too hard now. Will be testing its brinell hardness soon. Are there limits on the hardness for re-welding?
I am not a welding engineer and need some advise.
Thank you





RE: Rewelding on 4140 material Rotek slew bearing - previously welded
Can you provide any details as to how the welding was done (process), the amount of weld metal deposited, was preheat or stress relief was performed (temperatures)? Was nondestructive testing performed after welding?
The reason I am asking the above questions is to help you with a better response.
RE: Rewelding on 4140 material Rotek slew bearing - previously welded
Where should i start? NDT services I assume.
RE: Rewelding on 4140 material Rotek slew bearing - previously welded
1. Perform a surface NDT of the area or region to be welded. I would clean up the surface and either perform a wet fluroescent MT or Liquid Penetrant inspection.
2. If the NDT shows no reportable indications, I would re-weld using a qualified welding procedure and welder.
3. Preheat is a requirement for this base material, and it should be controlled using electric resistance heaters. Suggested is 450 deg F, minimum.
4. At this point, what are you welding on the slew bearing? Are you performing a weld build-up?
RE: Rewelding on 4140 material Rotek slew bearing - previously welded
Will be setting up a QWP and welders onsite are prequalified. The 4140 bearing( 1 1/2" thick ring) will be welded to the truck frame - 3/4" mild steel
I see in my AWS welding handbook that the tensile strength on 4140 drops significatly as tempering temp increases. (250 ksi to 180ksi)
Any thoughts on this regarding the heat applied to it from prior welding. They claim they put 5 passes of E70- rod on initial install.
Thanks for all your valuable input...much appreciated!!
RE: Rewelding on 4140 material Rotek slew bearing - previously welded
To avoid all these problems, why can't this bearing ring be bolted on to a manufactured collar that is only welded once to the truck frame? There has got to be an easier approach than welding, cutting, re-welding each time.
RE: Rewelding on 4140 material Rotek slew bearing - previously welded
If not, maybe you can (abrasively) cut the affected area out of the old rig frame, and bolt it to the new rig.
Mike Halloran
Pembroke Pines, FL, USA
RE: Rewelding on 4140 material Rotek slew bearing - previously welded
RE: Rewelding on 4140 material Rotek slew bearing - previously welded
RE: Rewelding on 4140 material Rotek slew bearing - previously welded