Effects of machining Q&T material...

[entx]

Will subsequent machining to already Q&T material effect the temper of the material? I have been asked this question and materials is not my specialty so I figured someone here must know the answer. I am told the material is 300 series stainless, but I didn't think 300 series is typically tempered? This is bar stock not sheet...

If it's an alloy or carbon grade that is Q&T will follow up machining step effect the tempering?

Thanks

 

[swall]

For low alloy, heat treated steels, the answer to your question is yes.It is a shallow effect and localized, much like grinding damage and can be avoided by using the proper feeds and depths of cut for the hardness of material you are working with.

 

[NickE]

300 series stainless would not be quenched and then tempered normally, it does not undergo an austenite to martensite transformation.

Machining of annealed 300 series stainless is a pain in the kiester. it work hardens rapidly, is stringy, and galls to the tool easily.

Use a high sulfur cutting oil, and the proper speeds and feeds. (lower speed, high feed)

 

[entx]

Hey NickE,

You mention it would not be Q&T normally, So would it be safe to say that the 300 series stainless is not Q&T.

But in any case what would ruin the temper? Would it be high heat? Or would it also be ruined by excess material removal?

Thanks

 

[NickE]

There is no "temper" applicable to 3nn series stainless steels. In the annealed condition they are heated to the solution temp and the quenched rapidly to avoid the precipitation of CrC.

If the steel is work hardened to some strength level then applying high enough temperatures will reduce the strength.

Nick
I love materials science!