Elongation in CG8M (317)

[lkrzyzan]

Hello all,

I'm having issues with elongation coming under the 25% ASTM A351 spec. Haven't found anything I can credibly go on in a literature review. Physical testing seems to indicate that a Cu content >0.45% is beneficial but there is not enough data to make this definitive. Also postively correlating is a higher Mn content (>1.1%)

HT: 1900 WQ

Thoughts?

Thanks,

lkrzyzan

 

[jwhit]

Your solution anneal temperature is barely adequate to dissolve carbides formed during solidification. Sometimes some sigma will form as well. I'd try and bump the temperature up to at least 1975f hold 1 hr. per inch and water quench as rapidly as possible. Realistically I would prefer going to 2050f. That should help. The increased Mo contributes to corrosion resistance in chlorides if I remember correctly. There is however a trade off with more sigma forming tendencies and higher ferrite content. Both of these reduce ductility.
Jeff

 

[lkrzyzan]

Increased Mn seems to have resolved issue. Likely more austenite.

lkrzyzan

 

[EdStainless]

Mn and Cu are weak austenite stabalizers. 0.5% Cu and 1.1% Mn are no problem, but you shouldn't need them.
Raise the anneal temp. You would need many hours at 1950F, I would use 2000F min for this Mo bearing grade.

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