Influence of the residual stresses induced by tool wear on the failure of brass electro-valves

Failure analysis was performed on different brass electro-valves body affected by unexpected phenomena of cracking. Through the application of optical and scanning electron microscopy, micro hardness Vickers test and X-ray diffraction, the causes of damage were identified. The study showed the dependence between roughness and residual stress associated to the tool wear. A solution to avoid the failure is finally proposed, based on the use combination of a tool with controlled wear and stress relieving heat treatment.