High speed laser cladding of an iron based alloy developed for hard chrome replacement

Tougher environmental legislations related to the usage of hexavalent chrome are forcing industries to search for new alternatives to replace conventional hard chrome plating [European Union, Off. J. Eur. Union 56, 1–5 (2013)]. In addition to the environmental aspects, the typical requirements of the coatings are smooth surfaces with high resistance to wear and corrosion [R. Weil and K. Sheppard, “Electroplated coatings, friction, lubrication, and wear technology,” in ASM Handbook, ASM International, edited by S. D. Henry (ASM International, Metals Park, OH, 1992), Vol. 18, pp. 834–839]. Furthermore, to be attractive to any high volume industrial application, a replacement solution must not only have technical, but also cost benefits. High-speed laser cladding is such a process that can replace hard chrome plating [T. Schopphoven, A. Gasser, and K. Wissenbach, J. Laser Appl. 28, 022501 (2016); T. Schopphoven, A. Gasser, and G. Backes, Laser Tech. J. 4, 26–29 (2017)]. If compared to conventional laser cladding, where the layer thickness normally ranges between 0.5 and 1.5 mm, the high-speed laser cladding process can produce layers between 25 and 500 μm in thickness. The resulting heat input as well as the dilution with the substrate is very low [T. Schopphoven, A. Gasser, and G. Backes, Laser Tech. J. 4, 26–29 (2017)]. Until now, nickel based alloys have mostly been used as hard chrome replacement with high-speed laser cladding [T. Schopphoven, A. Gasser, and K. Wissenbach, J. Laser Appl. 28, 022501 (2016); O. Raykis, Laser Tech. J. 1, 28–30 (2017)]. However, there is a need for new innovative coating materials. The novel iron-based alloy in this study, consisting of 18% Cr and 2.5% Ni, features very good wear properties and high corrosion resistance. In combination with high-speed laser cladding, this alloy delivers an environmentally friendly and cost effective solution with complete metallurgical bonding to the substrate.