What is the part,that you plan to manufacture nd why select CA6NM for a high temperature(what temperature) application? Traditionally,CA6NM was developed over 410 grade of castings for better impact and wear properties.
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"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year
Not enough information to make a valid comparison between these alloys. It is known cast Grade 91 will have much better high temperature strength properties in comparison to cast CA6NM because Grade 91 is a creep strength enhanced ferritic steel, and was developed primarily for use in the Power Generation industry.
Regarding corrosion applications in certain environments, the higher chromium containing alloy CA6NM (12%) will have better corrosion resistance in comparison Grade 91 (9%).
we use before CA6NM in casting exhaust parts that in contact with hot gasses but now purchaser want to replace it with Cast "9CR-1MO (V,Nb)" STEEL. I want to know that, this changing in material is because of price or performance?
I would certainly not recommend 9Cr-1 Mo ,grade to be used in traditional casting techniques. There are other grade of heat resistant stainless steels as per ASTM A297,you can consider those for your application.
As suggested earlier,it is advised you engage the services of a knowledgeable and experienced metallurgist. It helps!
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"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year
I have seen CA6NM used in traditional gas and large steam turbine casings where metal temperatures do not exceed 1000 deg F. The elevated temperature strength of the CA6NM shows a significant decrease above 1000 deg F.
If you want an alternative alloy that can be used go with a 1%Cr-1%Mo- 0.5%V casting. This alloy has been used by turbine OEM's for many years, is reliable for elevated temperature service and castable. I would not use Grade 91 cast material.
This is not cost driven, Cr is $1.5/lb and Mo is $18.
While the oxidation resistance of 9-1 is better than a straight 9%Cr I am not sure that it would match 13%Cr.
I am more concerned about castability and resulting properties.
CA6NM has proven toughness, which could be a problem with 9-1.
that is true its C12A. It is creep resistance steel but the part that we made is in contact with hot gasses such as SO2 ... and working temperature is 550 C.
For castability and weldability, CA-6NM is superior. Having about the minimum Cr required to qualify as stainless, it will have superior corrosion resistance (although if you leave it out in the rain it will develop rust). In my experience it is mainly a hydro turbine and pump grade.
lidbasky,
Please note that while 9Cr-1Mo-V casting is grade C12A under A-217, 9Cr-1Mo castings have grade designation C12.
Regarding high temperature strength at 550 C, agree with Metengr that C12A is superior to CA6NM but not C12.
Regarding oxidation resistance at 550 C, castability of the alloy and weldability of the alloy, I agree with metengr and brimstoner CA6NM will prove superior to C12A and C12.
