Investigation of ductile iron 'in ladle' treatment process parameter / Koh Bee Soon

Project paper (Bachelor of Mechanical Engineering with Manufacturing Engineering) -- Universiti Malaysia Pahang - 2009

Bibliography : p. 67-69

This dissertation deals with the parameters which will affect the quality of ductile iron produced using ‘In Ladle treatment’ process. These parameters included the percentage of magnesium ferrosilicon (MgFeSi) used and the castings size. The objectives of this project is to study and understand the inoculation and nodularization of ductile iron using ‘In Ladle treatment’ process, study on how percentage of magnesium ferrosilicon and castings size will influence the quality of ductile iron produced by “In Ladle” treatment process. Ductile iron studied in this dissertation is one of the most important materials in today industries due to its excellent mechanical properties plus low production cost. Therefore, it is important to establish a clear understanding on the parameters involved in producing ductile iron. This dissertation will describe how percentage of magnesium ferrosilicon used, range from 0.2% to 0.6% and casting sizes range from 0.5 kg to 1.5 kg, affects the mechanical properties of ductile iron castings produced using ‘In Ladle treatment’ process. The ductile iron castings are generated using green sand mold. The molten cast iron is transferred from induction furnace to a ladle; then from the ladle to green sand mold. The ladle will have a deep pocket where magnesium ferrosilicon is placed and the height to diameter ratio is 2.5:1. This technique is known as ‘In Ladle treatment’. After solidification, the ductile castings are removed from the mold and undergo analysis. The analysis included hardness, nodule counts, microstructure assessment and determination of iron grade. From the results obtained, it is observed that 0.2% of magnesium ferrosilicon is insufficient to convert cast iron to ductile iron. However, conversion to ductile iron is considered as successful when 0.3% to 0.6% of magnesium ferrosilicon is used and the types of castings produced are ferritic ductile iron. Nodule count and hardness of ductile iron is also influenced by the percentage of magnesium ferrosilicon. The results indicated that 0.4% of magnesium ferrosilicon is the optimum level which will give highest nodule count but lowest hardness number to the ductile iron. Based on the results obtained, lower casting size will result in higher nodule count and vice versa but casting size does not seem to have any obvious relationship with hardness number. The Vicker hardness as well as nodule count assessment concluded that when nodule count increase, the vicker hardness number will decrease.