The paper deals with identifying the causes of surface failure of a shaft made of material 42CrMoS4. On the basis of microstructural analysis completed by hardness testing. the occurrence of undesirable phases. such as non-metallic inclusions in the structure of the shaft. https://www.diegojavierfares.com/top-super-SOLD-Used-Olympia-Cremina-1979-Refurbished-120-volt-Brown-save-big/