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The IUP Journal of Mechanical Engineering
Process Factor Optimization for Controlling Properties of Gray Cast Iron IS: 210
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Cast iron is iron, carbon and silicon alloy and also contains other minor elements. To produce cast iron steel scrap, foundry return and pig iron are melted in an induction furnace. A new inoculant Sr-FeSi is added to molten metal during transfer of metal from the furnace to ladle. Sr shows better effect medium or high sulphur containing gray cast iron. An experiment is carried out with the full factorial method, and ANOVA is performed for finding the significant factor. In the paper, design of experiment has been applied to find the effect of chemical composition and inoculants. The paper also covers the effect of carbon, silicon and inoculants on the mechanical properties and microstructure. The results show that inoculant improves the property with an increase in the percentage of carbon and hardness and a decrease in tensile strength. Inoculant produces finer and small flake graphite.

 
 

Because of the good combination of castability, mechanical and technological properties, generally gray cast iron is used by the car industry, where there is an expanding interest in light metals. The final property of gray iron depends on the microstructure at the end of solidification, which is affected by many parameters like solidification rate, casting condition, chemical composition and inoculation practice. The characteristic of inoculant (some late added alloy at the time of pouring) is to impart for a reduction in shrinkage tendency. There are several techniques for inoculation like mold inoculation, ladle inoculation and stream inoculation. Ladle inoculation technique is the cheap and fast technique (Wending et al., 2016). It was found that gray iron inoculation can enhance the morphology and distribution of Type A graphite in the matrix. Inoculation also can increase the pearlite content and diminish the interlamellar spacing of pearlite (Chisameral et al., 2011; and 2012; Seidu, 2014; and Wending et al., 2016). Different types of gray iron composition are given in Figure 1. Gray iron comprises hypoeutectic and hypereutectic range, as shown in Figure 1 (Arthur, 2011). Rear-earth element can modify the morphology of gray iron (Aravind et al., 2009). The formation of steatite—having excessive phosphorus will result in increased brittleness and reduced hardness (Abbasi et al., 2007). In gray iron, if the carbon is in free condition then it develops flake graphite and if carbon is in combined form then it develops cementite. The distribution and size of flake affect the property of gray iron. There are five types of form denoted by letters A to E (Richard et al., 1976). Generally, Type A microstructure is preferred. Type D and Type E forms are generated at the rapidly solidified area, results in reduced mechanical properties.

 
 

Mechanical Engineering Journal, Inoculant, Gray iron, Tensile strength, DOE, ANOVA.