Abstract
The effects of σ-phase on the corrosion and unidirectional sliding wear behaviour of wrought duplex stainless steel (DSS) 2205 were investigated. The precipitation of σ-phase was induced by an isothermal aging at 850°C during 5, 15, 30 and 60min. Microstructural characterisation shows that the volume of δ-phase decreases as σ-phase increases. Dry sliding wear tests were carried out in a tribometer (model TRB, Anton Paar, Switzerland) with pin on disc technique at 7 and 15cm/s sliding rate with a load of 1N and an α-Al2O3 ball as counterpart. Results shown an important increase on wear resistance under dry sliding conditions after 5min of heat treatment due to the hardness provided by σ-phase on the DSS compared to base metal (BM). Nonetheless, cracks by Hertzian contact stress due to the difference of plastic deformation of matrix and σ-phase were observed at 15cm/s sliding rate in heat treated samples, induced by stress fatigue during the abrasion wear mechanism on the surface. Also there was observed that δ-phase is prone to dissolution in acidic media as σ-phase volume increases. Thus, results shown an improvement on wear resistance on samples aged for 5min in the starting critical intergranular corrosion susceptibility.
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