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CF12 Heat Treatment

Hi. I'm a student of metallury in Polytechnice University of Isfahan. I need some information about the heat treatment of CF12 (A kind of Stainless Steel) for my university project, would you mind please inform me about this or if it's possible tell somewhere (in internet) to find information about that.

Amin Taghavi
Metallurgy Student - Tehran, Iran
2004

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2004

I didn't find CF-12 even going back to a 1948 ACI listing (which included CF-10 and CF-16). CF-12M is a cast austenitic stainless steel; the 12 indicates 0.12 wt% max. C, and the M is 2-3% Mo. It is similar to 316 SS but somewhat higher in C and Si. CF-12 would have the same relationship vis-à-vis 304 SS.

It cannot be strengthened by heat treatment, but may be toughened. For maximum corrosion resistance and toughness, solution anneal at ~1100 °C to dissolve chromium carbides and any sigma phase and to homogenize solidification segregation, then quench. The annealing time depends upon the size of the part, but should be limited to minimize grain growth. E.g., ® hour for thin parts (~1/2Ö thick), 1 hr for 1Ö thick, 2 hr for 3Ö thick. A neutral (non-oxidizing, non-carburizing) or inert atmosphere or vacuum should be used. A rapid quench (water) is usually best, but where distortion or residual stress is a problem, oil quenching or rapid air cooling may be used.

Stress relieving depends upon metallurgical factors; do an Internet search. A complete stress relief is not usually performed due to sensitization (intergranular carbide, sigma formation). A partial stress relief for improved mechanical properties and stress corrosion resistance can be done at 500 °C for 2 hours. -- Information is primarily from several ASM Handbooks (www.asminternational.org) and MIL-H-6875H.

Ken Vlach [deceased]
- Goleta, California
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