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

Jackson, G.A.; Bai, M.; Pala, Z.; Hussain, T.; Sun, W.

Abstract

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 comprised FCC Co-Cr-W solid solution, 11 wt% M23C6 carbides and 7 wt% M7C3 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 as-sprayed coating whereas for the heat-treated coating, fracture along the carbide / matrix interface was the main fracture mechanism.

Citation

Jackson, G., Bai, M., Pala, Z., Hussain, T., & Sun, W. (2019). Small punch creep testing of thermally sprayed Stellite 6 coating: A comparative study of as-received vs post-heat treatment. Materials Science and Engineering: A, 749, 137-147. https://doi.org/10.1016/j.msea.2019.02.030

• Journal Article Type: Article
• Acceptance Date: Feb 9, 2019
• Online Publication Date: Feb 10, 2019
• Publication Date: Mar 11, 2019
• Deposit Date: Feb 18, 2019
• Publicly Available Date: Feb 18, 2019
• Journal: Materials Science and Engineering: A
• Print ISSN: 0921-5093
• Publisher: Elsevier
• Peer Reviewed: Peer Reviewed
• Volume: 749
• Pages: 137-147
• DOI: https://doi.org/10.1016/j.msea.2019.02.030
• Keywords: Small punch creep; HVOF; Stellite 6; Creep; Fracture; Mechanical properties
• Public URL: https://nottingham-repository.worktribe.com/output/1563535
• Publisher URL: https://www.sciencedirect.com/science/article/pii/S0921509319301923
• Additional Information: This article is maintained by: Elsevier; Article Title: Small punch creep testing of thermally sprayed Stellite 6 coating: A comparative study of as-received vs post-heat treatment; Journal Title: Materials Science and Engineering: A; CrossRef DOI link to publisher maintained version: https://doi.org/10.1016/j.msea.2019.02.030; Content Type: article; Copyright: © 2019 The Author(s). Published by Elsevier B.V.