International Journal of Applied Engineering Research ISSN 0973-4562 Volume 13, Number 5 (2018) pp. 2078-2083 © Research India Publications. http://www.ripublication.com 2078 Influence of Reheating in Pack Carburizing Process with Bamboo Charcoal and Cow Bone Powder Media for Hardness Number and Impact Strength Low Carbon Steel Sujita 1 , Rudy Soenoko 1 , Eko Siswanto 1 and Teguh Dwi Widodo 1 1 Department of Mechanical Engineering, Brawijaya University,Malang, Indonesia Street Mayjend Haryono 167 Malang 65145 Indonesia. E-mail: sujita@unram.ac.id Abstract Pack Carburizing process is the process of adding carbon element (C) into the metal, especially on the surface of the material where the carbon element is obtained from materials containing carbon so that the metal hardness can increase. Carburizing research that has been done with teak wood charcoal media and BaCO3 or NaCO3. The Pack Carburizing process is high costly. This study uses an alternative carburizing media in the form of bamboo charcoal and cow bone powder. The aim of this research is to know the difference of toughness value and hardness of low carbon steel which have undergone pack carburizing process, and reheating process of low carbon steel. The pack carburizing process was carried out at temperature 900 0 C for 7 hours carburizing time. The hardening process was carried out by reheating the specimens at 900° C, for 50 minutes holding time, cooled with air-cooled media, water and water + 30% salt. Then tested toughness and hardness test. While Scanning Electron Microscope (SEM) test is done to see the carbon diffusion after carburizing process in the form of a picture or photo. From this study it was concluded that with 7 hours of carburizing time, carbón diffusion and highest surface hardness were obtained in carburizing process, and cooling process with 30% salt + water cooling medium), the hardness number can increase up to 110% from the initial is 120.08 Kg /mm 2 Keywords: Pack Caburizing, Cooling, hardness, cooling medium, bamboo charcoal, cow bone INTRODUCTION All human needs cannot be separated from the metal element. So that metal has an active role in human life and support technology in today. Therefore, human efforts arise to improve the properties of the metal. That is by changing the mechanical properties and physical properties. The basic metal processing industry (blacksmith) which began to become the attention of West Nusa Tenggara (NTB) Regional government, is one of the bright prospect businesses. The need for equipment from metal is now increasing. However , in the NTB area this industry is still managed by the home industry is not fully managed by NTB local government. The products of home industry are the tools needed by the agrarian sector, such as machetes, hoes, knives, crowbars and others. Low carbon steel is also use for shipbuilding plates, shaft drive rods and others. The base metal used in this industry is low carbon steel which has the properties that is capable of forging and machine ability. Despite this low carbon steel still has a level of hardness number that has not been maximized. Carburizing is one of the most commonly performed steel heat treatments. For perhaps three thousand years it was performed by packing the low carbon wrought iron parts in charcoal, then raising the temperature of the pack to red heat for several hours. The entire pack, charcoal and all, was then dumped into water to quench it. The surface became very hard, while the interior or “core” of the part re- tained the toughness of low carbon steel [7-9]. Carburizing process is the process of adding carbon element (C) into the metal, especially on the surface of the material where the carbon element is obtained from materials containing carbon so that the metal hardness can be increased, the surface hardening on the metal can be done by adding certain elements to the metal such as carbon, nitrogen, and others. These elements can be obtained around us such as bovine bone, bamboo charcoal and others that may be unused again, but the carburizing process produces less harm to the metal [1][13][14]. Lack of carburizing process is the high cost of carburizing media and low hardness value of the metal can be improved by using alternative carburizing medium and cooling with different cooling media. The cow bone powder contains Calcium Carbonate and Tricalcium Fospat [2][12]. The results of this study became the reason to conduct research of surface hardening low carbon steel. This study uses air, water and water + 30% salt as cooling medium. The reason the three cooling media have different cooling properties and speed, so it is possible to see be different hardness value and the toughness value in the test specimen. Low carbon steel is also called mild steel or tool steel. This low carbon steel in the trade of its use is very broad as in the general construction steel which is made in the form of steel plates, strips and steel bars. Based on carbon content then low carbon steel can be use: Low carbon steels containing 0.1 to