Effect of normalizing temperature on microstructure and mechanical properties of ductile iron for piano iron plate

Piano iron plate is one of the components that play a decisive role in the quality of piano. In this paper, the effects of normalizing temperature on the microstructure and mechanical properties of nodular cast iron for piano iron plate were studied by normalizing at different temperatures and tempering at the same temperature. The microstructure observation, tensile test and impact test were used to study the effect of normalizing temperature on the microstructure and mechanical properties. The results show that after normalizing at 840 ~ 1 040 °C and tempering at the same temperature, the microstructure of ductile iron is mainly pearlite. In the normalizing temperature range of 840 ~ 1 040 °C, with the increase of normalizing temperature, the impact toughness and elongation of ductile iron increase, while the tensile strength and Brinell hardness show the opposite trend. When the normalizing temperature is 930 °C, the comprehensive mechanical properties of ductile iron are the best. At this time, the tensile strength is 815 MPa, the Brinell hardness is 328 HBW, the elongation is 3,79 %, and the impact toughness is 3,04 J / cm².