Weldability of 4140, 4340 to H13
Weldability of 4140, 4340 to H13
(OP)
The 4140 and 4340 would be hardened prior to welding. The components would be tack welded together, and are under varying compression forces (These are mating faces). Question is what type of welding rod would best fit this application ?
Cheers
Cheers





RE: Weldability of 4140, 4340 to H13
Why do you even want to weld after a hardening heat treatment? Why not before hardening using wed rod of similar chemical composition as the base metals you listed? This makes no sense and significantly increases your susceptibly to cracking either during or after welding. Also, the heat from welding will result in changed mechanical properties adjacent to the weld region.
So, with these reasons above, why do you want to weld after hardening????
RE: Weldability of 4140, 4340 to H13
RE: Weldability of 4140, 4340 to H13
Do you realize that for welding to H13 you need to preheat locally to at least 800 deg F? If you absolutely need to tack weld, I would recommend using an austenitic filler metal - 309 or Ni-base instead of a matching low alloy filler metal. The austenitic weld deposit will be lower strength but will be able to absorb residual stresses from weld shrinkage and to lessen the changes for cracking.
You also need to understand that welding to hardened H13 and 4140 and 4340 steels will require PWHT below the original tempering temperature used for hardening. This temperature should be 50 deg F below the original tempering temperature.
RE: Weldability of 4140, 4340 to H13
Also if you could describe some more,the application and relative sizes of the parts to be welded,better interaction could be possible.
I have not failed. I've just found 10,000 ways that won't work." — Thomas Edison
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RE: Weldability of 4140, 4340 to H13
Yes, the plate will only be tack welded at three points for retaining purposes.
Also, since yesterday, I found out that our supplier wasn't using 4340 hardened, as called for on the print. Some change was made many moons ago to go to a cheaper material, not hardened, which is why Im seeing the problems now. There was now update made to drawings etc. Slightly frustrating!! The application is on a 2000T Extrusion Press.
RE: Weldability of 4140, 4340 to H13
I have just been reviewing a customer's drawing. The composition is for a low carbon steel (close to 1020),but it specifies Cr min 0.5% and maximum 0.2%. I am surprised!
I have not failed. I've just found 10,000 ways that won't work." — Thomas Edison
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RE: Weldability of 4140, 4340 to H13