Study on technology of nodular cast iron for automobile hub support based on magma

Starting from the practical application of sand casting production process, the process design and material properties of nodular cast iron automobile hub support with high strength and toughness were studied; And use the three-dimensional modeling software ugnx12 0 and the nodular cast iron numerical simulation software magma as technical means, the nodular cast iron process of automobile hub support is simulated and optimized, and the main conclusions are as follows:

(1) The effects of Mn and Cu on the microstructure and mechanical properties of ball milled cast iron were studied. It was found that the increase of Mn content would reduce the spheroidization rate, while the increase of Cu content would increase the spheroidization rate. Both elements increase the content of pearlite in the matrix, promote the refinement of pearlite layer, improve the strength of the material, but reduce the elongation of the material. When the content of Mn is 0.2 ~ 0.4wt.%, The content of Cu is 0.3 ~ 0.4wt.% The tensile strength of the material is 736.67 MPa and the elongation is 10.6%, which meets the comprehensive performance requirements of high strength and Toughness Nodular Cast Iron for preparing automobile hub support.

(2) According to the structural characteristics of nodular cast iron, the casting process scheme of nodular cast iron was formulated. The mold filling and solidification process of the process scheme were simulated by magma casting simulation software. It is found that under this process scheme, the mold filling process of nodular cast iron is reasonable as a whole. However, in the solidification process, due to the low pouring temperature, the early solidification of the feeding channel of the riser neck and the insufficient feeding capacity of the riser, there are many shrinkage casting defects in the nodular cast iron.

(3) The process scheme is improved from the perspective of increasing pouring temperature. The simulation results show that when the pouring temperature is raised to 1425 โ„ƒ, the solidification time of the feeding channel is extended to 182.27 s, so that the riser can feed nodular cast iron for a longer time, which effectively reduces the shrinkage casting defects in nodular cast iron.

(4) The feeding capacity of the riser is further enhanced by changing the height and diameter of the riser and the length of the riser neck. It is found that only increasing the riser height can improve the internal shrinkage porosity of nodular cast iron to a certain extent, but the effect is limited, and when the riser is too high, it will lead to new contact heat joints on nodular cast iron. By increasing the riser diameter and shortening the riser neck length, the cooling rate of riser neck is further reduced, the action time of riser is prolonged, and the shrinkage casting defect volume in nodular cast iron is significantly reduced. When the size of riser is middle Riser: height 70 mm, diameter 60 mm, side Riser: height 90 mm, diameter 54.5 mm, and riser neck length 16 mm, the number of overall shrinkage porosity in nodular cast iron is the least.

(5) Adding cold iron in the thick wall area of the upper end cover where feeding is difficult improves the solidification speed of this part, promotes the simultaneous solidification of thick part and thin wall area, and eliminates the shrinkage casting defects in nodular cast iron through simulation.