Production Technics and Mechanical Properties of High Toughness Austempered Ductile Iron

In order to produce high toughness austempered ductile iron (ADI),the influence of chemical composition and heat treatment was studied.The chemical composition of the iron was designed by adding Cu,Mo,Ni.The high quality ductile iron roughcast was made by casting.The heat treatment was performed at austenitizing temperatures of 880-920 ℃ and then at austempered temperatures 350-370 ℃.The mechanical properties of the high toughness ADI sample are tensile strength 908-1 054 MPa,average elongation 11.8%,impact resistance 136 J,yield strength 744 MPa,and Brinell hardness 271 HB.The mechanical properties of the produced high toughness ADI excel the European Community ADI standard,but do not comply with the principle of the change between tensile strength and elongation,impact resistance,yield strength,Brinell hardness in ADI Standard EN1564.