preheating of 4340 2

[sinampot]

i am to build up a 40CrNiMoA or a 4340 with hardfacing material. At what minimum preheating temperature will I use?

 

[tbuelna]

What material and what process are you using for the hardfacing?

 

[metengr]

If you are using 4340 as the base material for the hardfacing weld overlay, you will need to preheat to at least a minimum of 400 deg F.

 

[sinampot]

i got a lot of problem in welding high carbon alloys, specially when it comes to heavy welding like build up and/or hardfacing. will you guys give me some idea on the easiest way how to know the minimum preheating temperatures to use.

 

[tbuelna]

Welding 4340 requires preheating, interpass heating, and post heating/stress relief with careful control of cooling rate. Here is a rough guide for 4340 preheating/interpass heating based on section thickness, but the optimum temperatures will depend on your particular welding process and overlay alloy. You can get a copy of AWS D1.1 section 5.6 for more detailed information, or you take a look at this document from Lincoln.

Good luck to you.
Terry