Heat treating 4340

[Hogg]

I posted a similar question a while back, under a different user name though.

Anyway, people were a really good help, but I need to know a little more.

Those of you who have heat treated 4340 before, after welding, what tempereature did you reheat too and how long for?

[leclercjs]

Hi,

we did a stress relief on our chassis and since two years, it seems to always work great!! For the time and the temperature, I'll have to check on the report the compagnygave us. I should post it before tomorrow morning.

[clausen]

Isn't welding 4340 no-no?

I know the guys at the motorsport engineering business that I work for on weekends only use 4340 for machined parts, and 4130 or 4140 for things that are welded.

Apparently the nickel in it is bad for welding? I think it's nickel

[-]

I think you are mistaking 4130 for the frame and 4340 for your drivetrain components.

As for welding 4340, its not recommended due to the trouble that can be caused by too much heat the presence of the Nickel in the alloy. Call up a local heat-treatment shop and ask them what temp to heat your part up to. I hope for your sake that you did your homework and use the right kind of filler if any was used

[Dave Cook]

Here is a link with some 4340 heat treating and welding info.

http://www.suppliersonline.com/propertypages/4340.asp#General