Higher Strength 316 SS Forgings 2

[TEV]

We source Type 316 stainless steel forgings for manufacture of some of our machined products. We need to get as much strength as possible in these forgings to optimize the performance of our products. We have specified Carbon and Nitrogen contents as high as our suppliers will accept within the spec composition range for Type 316, and requested that our forger control his forging temperature to as low as possible. (He was forging near the "splatter" temperature range, and is constantly b****ing about die life.) We are getting Yield Strengths in the low 40s ksi range and hardnesses in the low 80s Rockwell B. We would like to get higher YS and hardness > 90 Rb. Any suggestions on what other options exist for increasing these properties and still maintaining certification per ASTM A-182, Type 316?

 

[mcguire]

By raising carbon and nitrogen you are doing all you can to strengthen the austenite by alloying. But you are probaly driving doen the ferrite percentage if your supplier isn't raising chrome, moly, or silicon to compensate. You can increase the yield strength by 300 psi for each percent ferrite. Up to 9 or 10% won't hurt.
If you can't further refine grain size that's all you can do without changing grades. Have you considered 2205 with it's 60,000psi+ yield strength?
Can you put any cold work into the component?

 

[TEV]

McGuire: We have seriously considered 316N, and still may go that direction. We do not have the flexibility to go to the duplex alloy, although I would like to. The grain size is affected mostly by the forging temperature, and as I mentioned, I do not have confidence that it is being properly controlled. But that's an internal problem. Thanks for the heads-up on ferrite content. I frankly missed that, and it should have been obvious to me.