Tribological properties of laser clad Stellite 6 coatings on steel substrates

Abstract

The laser cladding of diesel engine exhaust valves is an emerging technology that provides excellent results in terms of the wear and corrosion resistance of the repaired materials. This work focuses on the deposition by laser cladding of Stellite 6 alloy coatings on two different base materials: an AISI 1045 carbon steel and an AISI 304 stainless steel. Following a process optimisation criterion, several of the fundamental laser treatment parameters were varied in order to obtain defect-free coatings with good adherence and minimal dilution. The metallographic structure of the clad material, irrespective of the substrate used, consists of a typical dendritic microstructure in a solid solution of Co. The mechanical strength of the layers was analysed by measuring HV0·1 microhardness and sliding wear behaviour. Laser coatings achieved hardness greater than 500 HV0·1, and presented excellent dry sliding wear behaviour, with a dimensional wear coefficient k one and a half orders of magnitude lower than that of the substrates. A combined oxidation and abrasion mechanism dominated the wear of the Stellite 6 layers, while in the case of AISI 1045 steel substrate, the wear was caused mainly by a surface oxidation mechanism. For the AISI 304 steel, the wear resulted from a combined adhesion, abrasion and plastic deformation mechanism.

Multiphysics simulation of laser–material interaction during laser powder depositon

“…The laser cladding process is defined as the process in which laser beam is used to fuse a material which has different metallurgical properties than the substrate, whereby only a very thin layer of the substrate has to be melted in order to achieve metallurgical bonding with minimal dilution of added material and substrate so that the original properties of the coating material are maintained [2]. In practice, laser cladding makes possible to solve problems such as wear of diesel engine exhaust valves [3], wear of tools made of high speed steel [4], reparation of mold steels [5], corrosion of gas turbine blades [6], and other problems that would be impossible solving using conventional methods, like heat treatment [7].…”

Thermal Fatigue Testing of Plasma Transfer Arc Stellite Coatings on Hot Work Tool Steels under Steel Thixoforming Conditions

“…The higher oxidation resistance of Stellite 12 coating is also evidenced by TGA ( Figure 5). [46,49,[59][60][61] The oxide formed on the Stellite 12 coating was found by energy-dispersive spectroscopy (EDS) analysis to be Cr-rich (Table II). The Cr content of the Stellite 12 coating, well above 20 wt pct, apparently facilitates the formation of a continuous (Cr,Co,Fe) 2 O 3 film during thermal fatigue.…”

Design and Production of Innovative Turbomachinery Components via Topology Optimization and Additive Manufacturing

“…Metallurgical aspects of several International Journal of Rotating Machinery 3 materials, such as for instance super-alloys, have been also investigated to understand the possibilities offered by AM in the turbomachinery sector [9]. Other works in literature deal with smart solutions for a wide range of applications including wear of diesel engine exhaust valves [10], corrosion of gas turbine blades [11], reparation of mold steels [12], wear of tools made of high-speed steel [13], and many others in which the conventional methods fail.…”