Investigation of mechanical properties and wear behaviour of borontempered ductile iron

In this study, mechanical properties and wear behaviour of borontempered ductileiron are investigated. Borontempering is carried out by boronizing at 900 ºC for 1,3 and 5 hours in powder medium, followed by quenching in salt bath attemperatures 300, 350 and 450 ºC for an hour. After tempering process, thespecimens are cooled at room temperature and then dried and washed with water.Microstructure analyses of the borontempered specimens are performed using theoptical microscopy and x-ray difraction. Boride layer thickness and the variationof its hardness from surface to matrix are determined. The borontemperedspecimens are subjected to tensile, impact and hardness tests. Wear experimentsare performed by means of ball on disc method in unlubricated condition and atroom temperature. Experiments are carried out under 10 N load and at 0.3 m/sslading rate. Friction coefficient is measured by using a load cell which is attachedto wear test machine. Wear tracks are examined with the optical microscopy.Amount of wear debris volume and wear rate are calculated by using profilometerresults.Optimum properties are obtained by borontempering heat treatment.Borontempering gives higher impact toughness than that of boronizing and highersurface hardness than that of austempering. Borontempered ductile iron showslower friction coefficient and wear rate than that of boronized and austemperedductile iron.