Small punch creep testing of thermally sprayed Stellite 6 coating: a comparative study of as-received vs. post-heat treatment

G.A. Jackson, M. Bai, Z. Pala, T. Hussain, W. Sun
2019 Materials Science & Engineering: A  
Thermally sprayed Stellite 6 coatings offer high wear and corrosion-erosion resistance at high temperature but the creep behaviour of such coatings is not well understood. In this paper, the microstructure and creep behaviour of a HVOF Stellite 6 coating was investigated. The coating was tested in the as-sprayed condition and after an isothermal heat-treatment of 1 h at 1050°C. The as-sprayed coating comprised FCC Co-Cr-W solid solution with 2-3 wt% HCP phase, whereas the heat-treated coating
more » ... mprised FCC Co-Cr-W solid solution, 11 wt % M 23 C 6 carbides and 7 wt% M 7 C 3 carbides. Small punch creep tests were conducted at 700°C on the as-sprayed and heat-treated coatings. The heat-treated coating exhibited minimum steady-state strain rates approximately 2 orders of magnitude lower than the as-sprayed coating when tested at similar loads, leading to times to failure approximately two orders of magnitude longer for the heat-treated coating within the selected load range. Fracture analysis showed cracking along powder particle boundaries was the main mode of cracking in the assprayed coating whereas for the heat-treated coating, fracture along the carbide / matrix interface was the main fracture mechanism.
doi:10.1016/j.msea.2019.02.030 fatcat:ws2nxcxouvdprgufti3agdoz3q