This study aims to determine the effect of the carbon coating on the physical and mechanical properties of the gray cast iron solidification in permanent mold for tapping end.
The material used to make the specimen is turning lathe the former scrap in the melt in an induction furnace and poured in permanent mold is coated with carbon which is done at the tapping end, then specimen tested in physical and mechanical properties. This testing is CE meter which in this test the iron is still in liquid form, testing the chemical composition then hardness testing and microstructure testing on parts that direct contact with the air and on the direct contact with the mold.
Test results CE meter at the end of the tapping obtained the highest temperature of 1286.2 °C, began to condense at temperatures of liquid (1164,1 oC), and is solid at a temperature solid (1113,8 oC). Chemical composition testing of specimens without the carbon coating is Fe (93.46%), C (3.52%), Si (1.95%), a specimen with a carbon coating Fe (93.36%), C (3.69% ), Si (1.95%). The test results of micro picture looks graphite and cementite, for direct contact with the mold coated carbon dominated by graphite, while for direct contact with the air is dominated by cementite. The test results hardness specimens without the coating carbon obtained hardness HRB 97.79 and for coated the carbon obtained HRB 91.97 on the sides and HRC 18.79 on the top. From the data it can be concluded that the addition of the elements carbon (C) on the specimens with a carbon layer by 0.17%, hardness the specimens with coating the carbon more soft because it is dominated graphite, for parts in direct contact with the air is dominated by cementite because in this case freezing faster
