Premature thermal fatigue failure of aluminium injection dies with duplex surface treatment

▶ The premature failure of an aluminium injection die with a duplex surface treatment (plasma nitriding and physical vapor deposition coating) was investigated. ▶ The origin of failure was attributed to the sulfur inclusions introduced into the surface of the tool by a sulfur-impregnated grinding stone used in the final polishing operation. ▶ The low adhesion of the CrN coating on the sulfur inclusions led to the spalling of the coating, the exposure of the substrate material and the nucleation of cracks. ▶ New evidence is presented on the influence of surface preparation and manufacturing processes on aluminium injection tool performance.