Abstract
Thermal fatigue (TF) is a common problem in many tool steel components. It is caused by thermal cycling in presence of internal constraints. The resulting thermomechanical stresses induce thermal cracking (heat checking). A laboratory test was developed to reproduce TF damage on a laboratory scale, under oxidizing conditions. Two different test configurations were used to induce unidirectional and bidirectional cracking. Nitriding impairs TF resistance of plain steel due to the easier propagation of cracks through the diffusion layer. The efficacy of PVD coatings is dependent on their oxidation resistance and microstructure. The higher oxidation resistance of AlCrN/AlTiN than CrN results in delayed crack initiation. TF resistance is increased if the coating is free of defects and the interface adhesion is good.
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This paper is based on a presentation at the 2nd Mediterranean Conference on Heat Treatment and Surface Engineering, held in Cavtat, Croatia on 11–14 June 2013.