Abstract
Improving the strength of grey cast iron wheel hubs will improve the safety of automobiles and have a great significance for energy saving and environmental protection. This paper systematically compares the calculation results of Python-based precipitation calculation and JmatPro software simulation with experiments. The results show that with a low mass fraction of niobium (0.098%) cuboid Niobium Carbide (NbC) precipitates do not form in the liquid phase; however, an elongated NbC niobium-rich phase may form during the solidification process and in the solid phase. However, cuboid NbC precipitates can be precipitated from the liquid phase when the niobium mass fraction is higher (0.27%, 0.46%). These results indicate that with the increasing niobium content the amount, particle size, and initial precipitation temperature of niobium carbide precipitated in the matrix structure will increase. According to the observation and statistical analysis of the microstructure, it is found that tensile strength will be improved with an increase in niobium content due to the refinement of the graphite and pearlite interlamellar spacing. In this paper, adding less than 0.32% of Nb to grey cast iron is recommended, considering the comprehensive cost and the effect of niobium in the material structure.
Highlights
IntroductionGrey cast iron is the key material for the wheel hub of domestic and foreign trucks
Improving the strength of grey cast iron wheel hubs improves the safety of automobiles and has a great significance for energy saving and environmental protection
The properties of the graphite flakes and pearlite were measured for a range of niobium contents, while the tensile strength was measured for alloys containing 0% and 0.32% Nb
Summary
Grey cast iron is the key material for the wheel hub of domestic and foreign trucks. Improving the strength of grey cast iron wheel hubs improves the safety of automobiles and has a great significance for energy saving and environmental protection. Grey cast iron is composed of a pearlite matrix, graphite flakes and precipitated carbides [1,2,3]. Due to the relatively simple production process, low cost, high recovery rate, high thermal conductivity, excellent machinability and casting performance, grey iron castings maintain a significant position in the market [4,5,6]. The method of adding a trace amount of niobium elements to improve the structure and mechanical properties of grey cast iron has received extensive attention [6,7,8]
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