API TR 21B PDF
This test program was designed to provide the data necessary to develop two independent sets of hardness conversions, one for precipitation hardened nickel alloys (PHNA) and the other for martensitic stainless steels (MSS), that could be used to ballot two new hardness conversion tables with corresponding hardness conversion equations for ASTM Standard E140.
The members of ASTM Committee E28.06.02 recommended the round robin hardness tests be performed at six different companies. The members of API Subcommittee 21 Task Group recommended the various alloys to test, and the desired hardness ranges for the test specimens.
