This documentidentifies commonlyused alloysteels, heattreatments and inspection requirements forthrough
hardened, case hardened and surface hardened gearing for main propulsion marine service over 1 500 hp.
Forged and hot rolled alloy steel bar stock are specified to two metallurgical quality grades (1 and 2) according
to cleanliness and testrequirements. Cast steel gearing is specified to a single metallurgical qualitylevel. Me-
chanical, metallurgical and nondestructive testrequirements are provided forvarious heattreatprocesses and
metallurgical quality grades of gearing.