Corrosion and Wear Behaviour of Boronized high Carbon and Chromium Cast Steel

摘要

The purpose of this study was to examine the effect of boronising heat treatment on the corrosion behaviour (in two different corrosive media) and wear properties (on two different counter sliding discs) of the DIN 1.4777 quality cast steel containing 1.7％ C, 30％ Cr and 1.1％ Si. The steel supplied as cast was exposed to homogenisation heat treatment at 1 150℃ for 3,5 hours and then to boronising heat treatment at 900℃ for 8 hours using the powder of Ekabor 2. An optical light microscope, SEM and XRD analyses were used to conduct microstructural characterisation of the steel investigated. Electrochemical potentio-dynamic polarisation measurements were taken to evaluate corrosion behaviours of the examined steels. Wear tests were conducted in a pin-on-disc type wear device by using a load between 10 N and 60 N. While the corrosion resistance of the boronising heat treated steel deteriorated by the pitting damage mechanism within corrosive media, uniform corrosion damage enhanced the corrosion resistance of the examined boronised steel. Oxidative adhesion, cracking of oxide and/or boride layer, and severe plastic deformation mechanisms were dominant during the wear tests. Severe plastic deformation and cracking of the oxide and/or boride layer caused wear mechanism to transform from mild to severe.