Microstructure of the surface layer of gray cast iron after hardening-finishing

Abstract

1. During surface hardening by ball burnishing and roller burnishing of gray cast iron microstructural transformations occur in the surface layer-the white phase occurs in treating pearlitic cast iron at low feed rates, the transformation of lamellar pearlite into divorced pearlite, the agglomeration of pearlite and partial transformation of ferrite into pearlite during treatment of pearlitic cast iron with increasing feed rates and during hardening of pearlitic-ferritic cast iron. 2. Ferritic cast iron is hardened hardly at all but there is danger of re-cold working and “peeling” of the surface layer. 3. The same character of transformations during hardening by ball burnishing (roller burnishing) and during the running-in period of wear causes the increased wear resistance of ball-burnished surfaces during the running-in period and the approximately identical wear resistance during the steady wear period for surfaces both hardened and not hardened before wear.