There are a number of excellent references available that give typical mechanical properties (including hardness) for all structural alloys (steel, cast iron, Al, Mg, Ti, etc.). If you are looking for only one reference, then Metals Handbook from ASM would probably be my suggestion. It is available as a Desk Edition (2nd Edition now) or as a CD-ROM from ASM at
One thing to consider-- not all metals are typically measured for hardness using the Brinell scale. There are several documents that give hardness conversions. ASTM E 140 is THE official standard, along with DIN 50150. SAE J417 is also appropriate. All of these documents can be obtained from Global Engineering Documents at
TVP,
Thanks for the help, but I have already looked into those areas, my company subscribes to all of them. I am still not able to find a high and low end brinell (regardless of units) for SA335 P91. I have read SA335 front to back and even looked at the similar spec in plate. No reference what so ever for the hardness.
The Brinell hardness of a material has a linear relation to the ultimate strength of the part. I don't know the exact equation, but if you know the ultimate strength of the material, then you can find the Brinell.
So if you can find a strength range for the material, which I am sure is given, you can convert to Brinell hardness. There are also charts which can compare the Brinell to any of the other hardness methods.
For carbon & low alloy steel the ultimate strength in psi is roughly 500 times the brinell. I don't think that holds true for other alloys.
I've found the best source for specifying minimum and maximum hardness values are your suppliers. They're not going to want you to spec something they can't deliver. Most can also provide you with some pretty good technical literature. I've got an excellent technical resource text from Corus and another from EMJ that didn't cost me a penny.
is another web site that provides good general info.
NACE specifies some material requirements for various service. NACE MR0175, for example, provides maximum hardness values for a wide variety of material for H2S service.
API 6A provides hardness requirements for various oilfield equipment. ASME B&PVC does the same for some of the materials used in pressure vessels. ASTM was allready mentioned.
SAE J417 gives approximate tensile strength values for various the various hardness numbers. So, based on the minimum tensile strength requirement for grade P91, you can obtain a minimum Brinell hardness number. Since there is no maximum tensile strength requirement, the high end is going to be somewhat nebulous. Your supplier should be able to tell you the maximum tensile strength that they can supply that will also meet the elongation requirements of SA335.
In some cases specifications do set hardness limits. But you need to remember that hardness is a very inaccurate indication of strength and microstructure. If you care you will check those.
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Corrosion, every where, all the time.
Manage it or it will manage you.
For applications requiring piping and boiler components, the range of hardness for Grade P91 is 200-250 BHN. This hardness range should only be used as a in-process Quality Control check, and has been suggested by various reputable manufacturers that routinely handle Grade P91 material.
