Effect of Coating Thickness on Fatigue Behavior of AISI 1045 Steel with HVOF Thermal Spray and Hard Chrome Electroplatin
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Effect of Coating Thickness on Fatigue Behavior of AISI 1045 Steel with HVOF Thermal Spray and Hard Chrome Electroplating Vinh Phoi Nguyen1 • Thien Ngon Dang1 • Chi Cuong Le1 • Dung-An Wang2,3
Submitted: 15 March 2020 / in revised form: 30 June 2020 / Accepted: 18 August 2020 Ó ASM International 2020
Abstract The effects of coating thickness on the fatigue lives of AISI 1045 steel shaft-bending specimens with WC10%Co-4%Cr high-velocity oxygen fuel (HVOF) coatings and hard chrome electroplated coatings under cyclic loading conditions are investigated. Residual stress distributions of the HVOF-coated layer and the hard chromeplated layer were measured. During cyclic fatigue testing, cracks are initiated near the interface between the HVOF coating and the steel substrate and propagate through the substrate to cause final fracture based on experimental results. For the specimens with hard chrome-plated coatings, the fatigue crack is initiated near the top of the coating, propagates through the coating, and then grows in the thickness direction of the steel substrate to cause final fracture. As the coating thickness of the HVOF-coated specimens increases, the fatigue strength of the specimens increases, which can be attributed to the fact that the magnitude of the compressive residual stress near the interface between the substrates and the HVOF coatings is higher when the coating thickness gets higher. As for the hard chrome-plated specimens, the fatigue strength is deteriorated when the coating thickness is increased. The microcrack density in the hard chrome coatings increases with the coating thickness and, therefore, may result in the decreased fatigue strength. & Dung-An Wang [email protected] 1
HCM City University of Technology and Education, Hochiminh City, Vietnam
2
Graduate Institute of Precision Engineering, National Chung Hsing University, Taichung, Taiwan
3
Faculty of Mechanical Engineering, Industrial University of Ho Chi Minh City, Ho Chi Minh City, Vietnam
Keywords coating fatigue hard chrome HVOF residual stress
Introduction Hard chrome plating can be applied to improve corrosion and abrasion resistance, and it can also be used to build up undersized or worn parts. With the low friction coefficient and high corrosion and wear resistance, chromium plating has been extensively used to improve properties of parts such as shafts, piston rings, engine valve stems, aircraft landing gear, and engine parts. The use of hard chrome plating, however, has been restricted due to negative environmental effects and health hazards. On the other hand, tensile residual stress and microcracks usually exist in parts with hard chrome plating; thereby, the fatigue strength and static load bearing capacity of the parts is reduced. Gawne (Ref 1) described that high tensile residual stress may be found in chromium coatings. They also discussed that the high residual stress generated during electroplating might be the source of the high dislocation densities in the deposited chromium layer. P
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