Welding 4130 Cr Mo

admin

Hi I was just wondering if you guys pre and post heat you Cr Mo when welding it? Some guys do and some guys don't, I read some of the books and they say you probably do more damage by pre/post heating it if you can't do it in a proper oven?  Any thoughts?
Reply:I weld 4130 everyday, but its all thin wall tubing for tube chassis's.  I do not preheat or post heat any of my frame weldments.  All suspension components are normalized and then heat treated to 130 ksi, but that is a different story.  All the tubing in the frames is 0.095" for the main roll hoop, but everything is 0.065" for the main cage, and the rest 0.049" and 0.035".According to the race car engineering books I have read, there is no real need to preheat or post heat anything .095" or less, but its good insurance.  If you are concerned, then you can get some of those temp crayons and do it.When I weld the axles up for the Formula SAE car, the wall is .120", and I preheat that.  Haven't broken anything yet.... knock on woodMechanical Engineer