The Influence of Carbon Particle Size in The Carburizing Process of ST-40 Steel to The Surface Hardness

This research aimed to determine the changes in the microstructure that occurred and changes in the hardness value of the steel surface. This research uses ST 40 steel and carbon powder with an average area of carbon particles 115,103µm2 and 515,735µm2. Steel and carbon were put in a closed container and heated at 780oC for 4 hours. After the carburizing process, the particle area was reduced to 110,051µm2 and 440, 058µm2. Raw material yields an average solubility of elements in Fe (β%) 5.99%. The solubility of the carburizing material element is higher in the smaller carbon grains. Likewise, the result of surface hardness after the carburizing process is harder by using small carbon granules.