Air-cooled 4130? Normalized then is temper possible?

[phonix]

I am going to be making a part that needs a lot of TIG welding. After welding, I need to make the yield strength as high as possible. Problem is, it has internal features and there is no way to oil quench it.

Knowing I can only air-cool -- what is the way to get the most strength?

I am assuming I should normalize it after welding (1650 degrees? For how long?)

I know this is a basic question, but is there any point to tempering it after normalizing it? I assume not since there was no hardening. But let me know if there is any benefit.

What will I have for 0.2% yield when done? 80,000PSI? Is it fair to say this is twice as strong as the 316SS we have been using?

 

[swall]

What sort of metal forms and section sizes are we talking about?

 

[phonix]

A 1.5 inch tube with caps welded on the end, and some internal parts. There are some holes to the outside, but there is no way oil would get to all sides at the same time.

 

[swall]

The best way to do what you want would be to harden in a vacuum furnace with high intensity gas quenching.

 

[phonix]

Do you know of shops that offer that kind of quenching? What kind of properties could I get from 4130 processed that way?

 

[CoryPad]

Vac-Met:

http://www.vac-met.com/

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[swall]

I dug out some old data I had for Timken 17-22AS, which is similar to 4130, except for .25 Vanadium, and thus higher hardenability. For a forced air cool normalize & temper on .505" tensile bars we got 126-131 ksi yield and 150-154ksi tensile.Granted, the hardenability of 17-22 is higher than 4130, but this data was for 1/2" diameter round stock and your tubing wall is a much thinner section. I would say you would have a good chance of hitting your 80,000 psi yield using a forced air quench and 800F temper.