Slurry Erosion Performance of Ni + xCr7C3 Microwave Composite Clad with [10–30 wt%] Cr7C3 Content

Abstract

In the present study, a series of Ni + xCr7C3 (x is the weight fraction of the Cr7C3) clads on hydro turbine steel (CA6NM) were developed through microwave cladding. The weight fraction of Cr7C3 was 10 wt%, 20 wt%, and 30 wt% in the developed clads. These clads were developed to mitigate the erosion induced degradation of the substrate surface. The Ni + 10% Cr7C3 composite clad exhibited poor erosion characteristics compared to Ni-based (Ni + 0% Cr7C3) clad due to embrittlement of the Ni-based matrix caused by dissolution of reinforced Cr7C3 particles. Maximum erosion resistance was exhibited by Ni + 30% Cr7C3, followed by Ni + 20% Cr7C3 clad. The enhanced slurry erosion performance of Ni + 30% Cr7C3 clad can be related to increased volume fraction of Cr7C3 carbides and other secondary phases, such as M7C3, Ni2Si. The average microhardness and fracture toughness of Ni + 30% Cr7C3 clad was on the order of 756 ± 37.8 HV and 12.9 ± 0.64 MPa√m, respectively. Analysis of eroded surface indicates that Ni + 30% Cr7C3 clad exhibited an optimum combination of hardness and fracture toughness for mitigation of slurry erosion.