Enhancement of carbide fraction in carburized spheroidal graphite cast iron by YAG laser

摘要

In order to increase the wear resistance, spheroidal graphite cast irons with ferritic matrix were carburized and/or alloyed with tungsten by YAG laser-beam surface melting. Laser-treated iron without alloying elements has a hypo-eutectic chillstructure with austenite dendrites. This micro structure can be changed to a hyper eutectic chill structure with primary cementites by laser carburization with graphite powder. Laser-treated iron with carburizing and tungsten alloying had hard WC carbide. The average hardness of a laser-treated iron without alloying elements, a carburized iron and iron both carburized and W alloyed were, 820HV0.1, 1100HV0.1 and 1150HV0.1 respectively. Pin on disc type tribo-tests revealed that these laser-treated ironshave excellent wear resistances. This laser carburizing process could easily be applied to low carbon steel and 18 Cr-8 Ni steel.