Abstract: In accordance with the AMS5678G material specification of 17-7PH stainless steel wire, metallographic method is required to test the depth of retained austenite on surface. In view of the problem of specimen preparation and the definition of the depth of retained austenite layer, the selection of specimen clips, erosion method and etching time, and depth definition of retained austenitic layer were tested. It is concluded that in order to avoid the influence of chemical erosion potential during retained austenite display, plastic sample clip should be used for inlay; using Fry's reagent to wipe the specimen with a wiping time of 5-10 s is a more suitable way to reveal the microstructure. When there is a retained austenitic layer on surface of the steel wire, its depth is defined as the dense retained austenitic layer depth, which is approved by the material specification unit.

Key words: 17-7PH steel wire, retained austenite on surface layer, depth test, metallographic method