2205 Duplex vs 316 ss Rockwell comparisson

[Reifleman2]

I am researching the differences in Rockwell numbers between 316 ss and 2205 Duplex (I am not a metallurgist, so bear with me ).

I understand the inherent advantages and disadvantages of 2205 Duplex vs 316 ss (austenite and ferrite structures and what that implies) but the range of Rockwell numbers for 2205 were 31 C (max) but 95 B (max) on 316 ss. I realize the scales are different, so how do I compare the two ratings properly (B and C scales)?

I expect the Rockwell rating to be better on the 2205, but I may be wrong.

Thanks in advance.

 

[Metaljon]

There is no unifying table covering the austenitic and duplex materials. If you have a look at ASTM E140 there are some tables that show the relative hardness for austenitic steels difference between B and C scale. This will give you some relative scale understanding. If you use the A scale as the intermediate scale this will give a relative hardness approximation. The B scale ends at 100HRB which is approximately 61.5 HRA. The C scale starts from 20 HRC which is approximately 60.3 HRA.

 

[stanweld]

The different scales are not really comparable at the maximum hardness limits provided. Rb 95 is outside the range of the C-Scale and Rc 31 is outside the range of the B Scale. Furthermore, the hardness values are not comparable between the two materials. If the materials were carbon or low alloy ferritic steels, the Rb 95 is somewhat comparable to Rc 15 to 16. The Rc 31 is somewhat comparable to Rb 106 - 107.

 

[Reifleman2]

Perfect, thank you for the clarification and info. Very helpful.

 

[EdStainless]

In physical reality Rockwell hardness does nothing, it is tensile strength that you actually use when you apply a material.
Look at your specs, what is the minimum specified strength for the alloys.
In most product forms the minimum required properties are:
alloy UTS yld hardness
316L 70ksi 25ksi RB 90 max
2205 95ksi 70ksi RC30 max

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