In order to obtain nodular cast iron that meets the requirements of high strength and toughness of automobile hub support, based on the chemical composition of QT450-10 nodular cast iron, which is the most commonly used material for hub support casting in China, this paper uses alloying means to further improve the strength of the material by adjusting the content of Cu and Mn while ensuring the plastic toughness (elongation ≥ 10%).
(1) Based on the composition of the existing national standard QT450-10 nodular cast iron, three groups of high strength and Toughness Nodular cast Iron for manufacturing automobile hub support were designed. The effects of alloying elements Mn and Cu on the microstructure and mechanical properties of nodular cast iron were studied and discussed.
(2) With the increase of Mn, the spheroidization rate of the sample decreases, the number of graphite balls decreases, the content of pearlite in the matrix increases and the content of ferrite decreases; With the increase of Cu, the spheroidization rate increases and the content of pearlite in the matrix increases significantly. Both elements promote the refinement of pearlite lamella, but Cu has stronger action ability.
(3) With the increase of Mn and Cu content, the pearlite content in the matrix increases, the material strength increases, but the elongation decreases. When the addition of Mn is 0.2 ~ 0.4 wt.% and the addition of Cu is 0.3 ~ 0.4 wt.%, the comprehensive properties of nodular cast iron sample are the best, the tensile strength reaches 736.67 MPa and the elongation is 10.6%, which meets the performance requirements of the designed high strength and Toughness Nodular Cast iron material. Therefore, the nodular cast iron with this composition is selected as the material for subsequent simulation research.