Evaluation of Abrasive Wear in UNS S32101 and S32750 Duplex Stainless Steels Submitted to Friction Stir Processing

Abstract

Duplex stainless steels are largely applied in petrochemical industries due to their high corrosion resistance and mechanical performance. Their applicability also requires a great wear resistance, which can be enhanced by friction stir processing (FSP), a surface hardening technique. In this work, FSP is utilized to process surfaces of UNS S32101 and UNS S32750. The materials were analyzed by EBSD in order to determine grain size and phase fraction. Microhardness tests were used to verify and compare the shifting of hardness values from 296 ± 8 to 314 ± 11 HV0.2/15 and from 323 ± 8 to 350 ± 8 HV0.2/15 for UNS S32101 and S32750, respectively. Abrasion tests were executed to study the wear behavior of both processed and unprocessed alloys. Abrasion tests indicated that the hardening by FSP promoted decrement of abrasive wear resistance. Volumetric loss increased after FSP, from 52.1 ± 0.5 to 53 ± 2 mm3, for UNS S32101, and from 50 ± 2 to 56.3 ± 0.3 mm3 for UNS S32750. Tensile tests results were fitted to Hollomon’s equation in order to identify mechanical properties and tendencies of strain hardening. SEM images were used to classify the wear micromechanisms acting on the samples. The results suggest that FSP can promote modifications of wear mechanisms and these changes can be correlated to the alloys’ microstructure.