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4130 and 4140 heat treat and filler

by David
(NC Charlotte)

Hello I have a piece of 4130 that I want to weld to 4140. what filler should I use and what gas (mix or pure argon)
both parts are over an inch thick and will require a preheat. I'm assuming 400+ degrees (f). Also after the weld how much heat is needed for heat treat and I assume slow cool, I was thinking sand or cat litter for insulation.

Thanks David



depending on the end use of the weldment, there are several choices.

Filler metal could even be mild steel er70s2 if full hardness and strength are not an issue.

309 stainless rod could also be used and might be more crack resistant for this application.

the link above recommends a very high preheat

400 degree Celsius = 752 degree Fahrenheit
to slow the cooling rate.

4140 is often used for dimensional stability rather than complete strength and hardness being the main factors..
but If this is a critical weld, you should get engineering input.

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