Experimental investigations on fracture toughness and transition temperature in hard chrome coated structural materials

This experimental investigation is devoted to the analysis of the influence of hard chrome coating and service temperature on the fracture toughness of structural materials. The experimentations have been carried out on C15 steel and EN8 steel. The fracture toughness of these materials is investigated over a wide range of temperature and coating thickness. The fracture toughness of these materials is determined under mode-I condition, using CVN impact testing machine. Specimen preparation and testing were carried out according to ASTM E23 standards. Results of the experimental investigation have shown that, the service temperature and coating thickness play a significant role on the fracture behavior of these materials. The coating thickness has a great impact on the fracture toughness of the material. Also, it is identified that the transition temperature of the coated material is more than that of the normal one. The test results showed that there is a particular range of temperature and the coating thickness with in which the material can give effective service. The nature of fracture, transition temperature and other micromechanisms of fracture are precisely analyzed with the aid of SEM fractography. It is found that the cleavage triggering sites have maximum influence on the fracture toughness of the coated materials.