Thermal fatigue of hot work tool steels: a review on damage mechanisms, performance improvement, and evaluation methods

Thermal fatigue failure is one of the main factors affecting the service life of hot-working dies. Thermal fatigue resistance also plays a fundamental role in work safety and cost saving in the rapidly developing automotive industry. The recent studies on the thermal fatigue phenomenon of hot work tool steels are reviewed. Those researches primarily focus on damage mechanism, performance improvement, and evaluation methods, encompassing both testing methods and life prediction. Compared to previous researches, notable progress has been made in the following areas: damage mechanisms have been extensively studied from macroscale to microscale. Furthermore, damage mechanisms in different fatigue regimes have also been investigated. In terms of improving the thermal fatigue resistance of hot work tool steels, additive manufacturing is increasingly being adopted as a novel forming method, particularly for designing conformal cooling channel systems in dies. Regarding the evaluation methods for thermal fatigue behavior, iterated numerical analysis and elaborated finite-element models are playing an essential role in predicting thermal fatigue life. This field is currently undergoing tremendous evolution. Finally, current challenges and future research directions are presented for incoming investigators. It is acknowledged that significant scope remains for advancing these areas to more effectively guide the practical manufacture and application of hot-working dies.