AMS6421H Steel, Bars, Forgings, and Tubing 0.80Cr - 0.85Ni - 0.20Mo - 0.003B (0.35 - 0.40C) (Modified 98B37)

AMS6421H is a Five-Year Review and update of this specification that revises analytical methods (3.1), grain size determination (3.1.1 and 3.2.2), macrostructure (3.3.1.1, 3.3.1.2), hardenability (3.3.3), decarburization (3.3.4.5), quality (3.4.2); adds prohibition of unauthorized exceptions (3.6); and revises classification of tests (4.2), reporting (4.4), and identification (5.2.1).