Study on the Double-Fined Treatment and Superplasticity of GCr15 Die Steels
Heat treatment has a signifieant impact on the performance of the GCr15 die steel. Using scanning electron microscopy, optical microscopy, hardness tester and tensile testing machine analyses the influence of double-fined treatment on microstructure and mechanical properties of GCr15 steels. The results show that the double-fined treatment can make the carbids which haven’t insoluted fine to 320nm and the grains fine to No. 10. The dislocated martensite become more after double-fined treatment; at the same time, there are more sheet-retained austernite in lathy martensite and around sheet martensite; broken-orifice changes from definitely cleavage brittleness fracture to definitely cleavage tenacity fracture. By double-fined treatment, die steel can be given the neeessary strength and toughness, and the life can be substantially increased. The superplasticity of GCr15 die steel was improved by double-fined treatment. The optimal temperature range of the elongation is: 680~780°C. Anti-oxidants can improve the elongation of GCr15 steels.