The Effect of IN718 Superalloy Swarf Machining Addition and Normalizing on the Microstructure and Mechanical Properties of Hypereutectic Gray Cast Iron Produced by Lost Foam Method

Cast iron has a special place in various industries due to its low price and production ease. It seems that the use of machining chips is a suitable solution for alloying and increasing the mechanical properties of cast iron. In this research, continuous swarf resulting from IN718 machining with aligned placement in the foam was carried out. After placing the swarf, GG20 cast iron was cast by the lost foam method. After casting, the composite and simple samples were normalized at 900ºC. Microstructural studies were showed that the structure contains type A and C graphites and fine pearlites in the presence of chips. Also, the presence of swarf disturbed the solidification balance, which ultimately resulted in the presence of ferrite areas in the vicinity of the swarfs. As a result of normalization, the C graphites of the simple sample were removed entirely. Allotriomorphic ferrite was formed in the composite sample at the interface, and fine A-type graphites were distributed in fine pearlite matrix. The addition of swarf increased the hardness from 132 to 153 HB due to the creation of local saturated solid solution, compositing, and normalizing due to the mentioned microstructural changes the hardness of both samples increased to 148 and 180HB. Swarf acted as a barrier against crack growth causing the formation of soft phases and finer pearlite and graphite. The sample’s impact energy increased from 3 to 3.5J. With normalizing, the fracture energy of the simple sample increased to 4.12J while the composite sample to 6.1J.