Metallographic Evaluation of Increased Susceptibility to Intermediate Embrittlement of Engine Valve Forgings Made of NCF 3015 High Nickel and Chromium Steel

This paper focused on determining the increased tendency of cracking after die forging process high nickel and chromium steel. The increase in carbon content austenitic nickel–chromium steel promoted valve forgings to intergranular crack head. Attention was paid issues related chemical composition material be considered when hot forming components. Optical scanning electron microscopies were used examine microstructure fracture features samples removed from a fractured embrittlement due microcavity formation at grain boundaries. Creep theory boundaries explain formation. tensile behavior interpreted evolution during deformation referred intermediate brittleness effect carbon. It found that strong undercooling observed edges head are factors promote reduction boundary cohesion enhance temperature embrittlement. Finally, it heterogeneous structure manifested by presence M23C6-type carbides matrix most likely occurring brittleness.