The effect of residual stresses in 100Cr6 at different hardness on the obtained HVOF-coatings

Mohamed Abdulgader, Institute of Materials Engineering / TU-Dortmund, Dortmund, Germany
Wolfgang Tillmann, Chair of Materials Engineering / TU-Dortmund , Dortmund, Germany

The formation of residual stresses in thermal sprayed coating is due to the high temperatures and the subsequent cooling of the deposited material. The induced stresses effect directly the adhesive strength, wear resistance and toughness of the coating. This work investigates the relationship between residual stresses, heat treatment and the coating performance. The samples were made out of bearing steel 100Cr6 and have a diameter of 15 mm and are 226 mm long. They were delivered in three degrees of hardness (HV 270, HV 460, HV 800). Furthermore, the effect of substrate preparation on the induced residual stresses was investigated. The effect of induced stresses on the coating properties was also determined. The heat treatment shifts residual stresses of 100Cr6 into an increased tensile stress. The stresses induced by substrate preparation are compressive stresses. However, the applied coating shows tensile stresses. The residence time of the spray flame on the substrate has a strong influence on the induced stresses. With a shorter residence time, the tensile stresses become larger. The induced residual stresses have no direct influence on the wear resistance. No correlation could also be found between the induced residual stresses and the phase composition of the produced coating.

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