Minimum Hardness according to NACE and API 6A 2

[Runus]

The maximum hardness according to NACE and API 6A is 250 HV. I can't find the requirements for minimum hardness in these standards. What is the minimum requirements? (It is PWHT)

 

[rneill]

There is no requirement for minimum hardness. There are requirements for minimum yields and tensiles in applicable material standards but not hardness. As long as you are below the maximum you are fine.

 

[DVWE]

If you want a rough estimation of minimum hardness, you can multiply the number in Brinell Hardness * 500. For example 150 BHN * 500 = 75ksi. This should be used for estimation purposes only.

 

[19Delta]

I have a similiar problem. I need either a min or max hardness for austenitic stainless steel and cannot find it in API6A. The only suggestion i have had is to use the same hardness that is used for the rings. What do i put on the drawings?

 

[pavanbhav]

The minimum hardness correlates to the minimum required tensile strength for your part. For example, an API 75k material designation has a 95ksi tensile requirement. So your minimum hardness would be about 197 BHN and you max would be aboud 235 BHN (= 250 HV or 22 HRc).

API doesn't get into hardness for austenitics, but you should be able to find them in an ASTM spec. try ASTM A182 for forgings.

The bottom line is that hardness is a direct representative of the tensile strength of the material.

 

[19Delta]

That's great advice, I'll look in the ASTM A182 that our metalurgist gave me.