Study And Practice On Carbon Eqiuvalent Of The Dongfeng Car Safeguard Castings

The nodular cast iron has high intensity and toughness, good wear ability and heat property. As an important engineering material, nodular cast iron is widely used in each department of national economy. To automobile industry nodular cast iron is especially important, because many vital parts such as bent craft, many kinds of safeguards are made of nodular cast iron.Aiming to the production of car safeguard castings, the effect of carbon equivalent on casting characteristics and mechanical properties of the nodular cast iron and quality of the castings were systematically investigated in this paper in the condition of production in Foundry 2, Dongfeng Motors. The results show:1 )The carbon equivalent has some effect on casting characteristics of the nodular cast iron. The flowing ability of the melt increases with the increasing of carbon equivalent.2) The carbon equivalent has immediate effects on as-cast structure and mechanical properties of the nodular cast iron, so the properties of the casting can be controlled by adjust CE value.3) The amount of carbon and silicon affects spheroidization of graphite. The higher of the amount of silicon, the more of the number of graphite, and the better of the shape of graphite. But excessive silicon amount will bring the defect of graphite floating.4) The carbon equivalent has significant effects on shrinkage hole and shrinkage porosity of castings, the volume of shrinkage hole increases with carbon equivalent up to 4.2%, then the volume of shrinkage hole decreases and shrinkage porosity increases when carbon equivalent continues to increase. In the range of production increasing silicon content can decrease the volume of shrinkage hole but has little effect on shrinkage porosity.Based on the results and according to the condition of production, a practical and scientific method was proposed to control the carbon equivalent of the nodular cast iron. Practice in production shows that the method can reduce the defects and wasters of castings and improve the quality of casting. So the mass production of car...