Study on Brittle Fracture of Medium Manganese Steel

Water toughened medium manganese steel demonstrates good workability after annealing treatment, while water retoughening after machining, lead the steel brittle fracture combined with cleavage and inter-granular fracture in room-temperature tensile tests, and considerable drop down in ductility. Research was made on the brittle fracture with methods including fracture morphology, microstructures, X-ray diffraction and surface analysis. The results showed that the inter-granular fracture resulted from aggregation of impurities in grain boundaries, and the cleavage fracture closely related to accruing of large number of inter-granular fractures and existence of deformational twins inside austenite grains. The cleavage plane is the close-packed plane (111) of a F. C. C structure.