Effects of different surface states on gas nitriding of gears

Through experiments investigating the effects of different surface states of quenched and tempered 42CrMo gear steel on gas nitriding, it is concluded that increasing surface roughness within a certain range can enhance nitrided case depth; surface compressive stress reduces case depth and nitrided surface hardness; acid-etched surfaces improve case depth and nitrided surface hardness;Finer and more uniform matrix microstructure with higher matrix hardness in the quenched and tempered condition results in greater case depth and higher nitrided surface hardness.