The course is designed to familiarize students with the fundamental mechanisms of production and operation degradation of the properties of engineering materials, in particular steels and other metals. The knowledge obtained will provide on one hand for a more accurate determination of the limit state and a more effective exploitation of the materials used and, on the other hand, for a qualified estimate of failure causes. Production degradation (metallurgy, purity, chemical and structural heterogeneity, and effects of welding as an example of the effect of the technological process itself). Operation degradation (corrosion, hydrogen embrittlement, wear, radiation embrittlement, and structural stability). The nature of the degradation process is always made clear, together with methods of evaluating it and its effect on the properties of materials. Methods of analysing the causes of defects in machine parts, including practical examples. Students are made familiar with selected methods for predicting the service life of machine parts.