Change in Wear Resistance of Iron Based High Carbon—High Chromium Hard Overlay by Heat Treatment

Abstract

Iron based high carbon - high chromium hard overlay is used in order to give a high wear resistance for abrasive parts. As weld, this hard overlay has a microstructure with primary precipitated carbide M₇C₃, secondary precipitated carbide and matrix gamma-phase, and has a hardness of 800—900 HV. For this hard overlay, the influences of heat treatment to the wear resistance were investigated. The wear resistances of the hard overlay did not change at the heat treatment conditions of 773 K (500 degree C) x 1 hour or 823 K (550 degree C) x 1 hour. But these dropped down at the heat treatment conditions over 823 K. Hardness of the hard overlay changed like as the wear resistance. These phenomenon were affected by the microstructure change that gamma - phase in the matrix phase of the weld metal transformed to alpha - phase by heat treatment at the conditions over 823 K.