Study on the Non-Shrinkage Casting of a Nodular Cast Iron Automobile Steering Knuckle

Author of the article:LIU Peixin1 , CHI Enlai1 , CUI Hongbao2

Author's Workplace：1. Yantai Pengcheng Auto Parts Co., Ltd., Yantai 264000, China; 2. School of Materials Science and Engineering, Henan Polytechnic University, Jiaozuo 454000, China

Key Words：nodular iron; knuckle; eutectic degree; shrinkage porosity

Abstract：A nodular cast iron automobile steering knuckle is a multihot-spot casting. Due to the mushy solidification characteristics of nodular cast iron, defects such as shrinkage cavities and porosities often occur in casting, which requires an increase in riser feeding, resulting in a decline in the yield rate and the complexity of the casting process design. In this paper, graphitization expansion was fully utilized to feed an automobile steering knuckle with multiple hot pots. The thermal analysis curves of cast iron were measured to obtain the relevant parameters, and the effects of different eutectic degrees and various inoculation combinations on the shrinkage porosity of nodular iron steering knuckles were analyzed. The results show that non-shrinkage nodular cast iron automobile steering knuckle casting without riser can be obtained by adjusting the eutectic degree of molten iron close to 1 and eutectic undercooling degree of solidification temperature curve close to zero, and using silicon carbide pretreatment, wire feeding inoculation, floating silicon inoculation, ladle inoculation and flow inoculation, which significantly improves the yield rate.