Physical vapor deposit (PVD) coatings have been used to extend die-casting die life, mainly by reducing molten metal’s corrosion and erosion to the dies. The dies are made of hot-work tool steels. Among the tested PVD coatings, CrN and TiAlN coatings provided the longest die life because of their higher oxidation resistance temperatures. Die insert life can be extended three to eight times based on the in-plant tests. However, the thermal fatigue resistance of hot-work tool steels was affected differently by the PVD coatings. The research work in this area is very limited.
This paper discusses the results from a systematic study involving three H series and two maraging hot-work tool steels with and without TiN, TiAlN or CrN PVD coating, in terms of thermal cycling induced fatigue (heat checking) resistance, hardness and fracture toughness changes, as well as molten aluminum corrosion resistance. Based on the results, a die life extension approach is proposed to reduce die-casting operation cost and improve casting quality.