Influence of the handling parameters on residual stresses of HVOF-sprayed WC-12Co coatings

• Handling parameters have an important influence on residual stresses of WC–12Co coatings.
• An increase of substrate temperature and coating thickness leads to rising stresses.
• A decrease of the handling parameters increases compressive residual stresses.
• With increasing specific material removal rates during grinding the stresses rise.

In this research work HVOF WC–12Co coatings were deposited on C45 steel (1.0503) substrates. Unfavorable residual stresses can lead to delamination and spallation and thus have to be avoided by optimizing the handling parameters. This study investigates the influence of the following handling parameters: substrate temperature, number of overruns, stand-off distance, track pitch, and gun velocity on the residual stress and hardness. Additionally, the effect of post-treating the coating by means of surface grinding was determined. For the HVOF spraying experiments, fine agglomerated and sintered WC–12Co powders (2–10 μm) with WC particles in the submicron range (400 nm) were chosen. It was determined that alterations of these handling parameters had significant effects on the residual stress and the hardness.