Improved slurry erosion resistance of martensitic 13wt.%Cr–4wt.%Ni steel subjected to cyclic heat treatment

Abstract

To increase the slurry erosion resistance, cyclic heat treatments were performed on 13wt.%Cr-4wt.%Ni steel at 1050 °C for 3, 5, 7, and 9 cycles. Microstructures in as-received and cyclic heat treated (CHTed) conditions were analyzed with the help of optical, SEM, XRD, and TEM. The structure-property correlations were then studied after determining the hardness, microhardness of each phase, and tensile properties. It was observed that the dissolution of M23C6 carbides caused the lath widening which deteriorated the microhardness of the martensite in the CHTed specimens. The increased hardness and tensile strengths were attributed to the reduced delta ferrite and the refined blocks in the CHTed specimens. Slurry erosion behavior of as-received and CHTed specimens was tested by conducting a 24hrs erosion test on slurry pot tester. The CHTed specimen possessed 69.9% higher slurry erosion resistance due to higher hardness and yield strength. During the first 12hrs of erosion, the subsurface hardening due to work hardening reduced the erosion rates significantly while the progressive loss of erosivity of the sand particles reduced the erosion rates in later hours of erosion test. AFM visualized the plastic deformation as a predominant erosion mechanism for all the specimens.