Simulation of Low Pressure Carburizing and Low Pressure Oil Quenching Process using ABAQUS for Finding Distortions in Component S. P. Wadkar † , Himanshu J. Patil $ , Shubham R. Tiwari $ Abstract - In this paper, based on the principles of heat transfer and thermal elastic-plastic theory, the heat treatment process optimization for dog clutch gear is proposed according to the structural characteristics of the gear and material properties of SCM415. To simulate the effect of Low pressure carburizing and Low pressure oil quenching process on tooth deformation and residual stress distribution, a heat treatment analysis model of gear is established, stress and deformation of gear teeth changing with time are analysed. The simulation results show that gear tooth hardness increases, tooth surface residual compressive stress increases and tooth deformation decreases after heat treatment process optimization. It can be beneficial for improving the fatigue strength and performance of gears. Keywords – Carburizing, Distortions in treatment, Gear, Heat Treatment, Quenching, I. INTRODUCTION A. Carburizing Carburizing is the process of diffusing carbon into steel so that the surface will become harder. Steel is surrounded with some form of graphite then high temperature and pressure added to the system so that the carbon can diffuse into the steel. This method is limited by contact between the steel and the carbon so it often has problems with the continuity of the case depth. Carburizing can also take place in gas atmospheres at or near standard atmospheric pressure. This method is attractive because a vacuum is not required so some processing cost can be reduced. However, the gas interactions do not allow even case depths. While the gas can easily strike exposed areas such as the top-land of a gear tooth the gas has problems distributing enough carbon at the root of the tooth. This happens because the carbon rich gas will initially strike the tooth root and the carbon will diffuse into the steel. In the last several decades vacuum carburizing was created. This occurs by creating a weak vacuum (10-25 Pascal) around the part to be carburized and then a small amount of carbon rich gas is introduced into the atmosphere. This gas increases the pressure to about 80,000 Pascal in vacuum carburizing and 450 to 1700 Pascal for low pressure carburizing (Benitez). The gas will move very rapidly and because physics dictates that atoms and molecules S. P. Wadkar† - †Assistant Professor, Department of Mechanical Engineering, MIT College of Engineering, Kothrud, Pune, Maharashtra 411038, India. Himanshu J. Patil$ - $ Department of Mechanical Engineering, MIT College of Engineering, Kothrud, Pune, Maharashtra 411038, India. Shubham R. Tiwari$ - $ Department of Mechanical Engineering, MIT College of Engineering, Kothrud, Pune, Maharashtra 411038, India. E-mail Addresses – swapnil.wadkar@mitcoe.edu.in (S. P. Wadkar) h.jagdish.patil@accenture.com (Himanshu J. Patil) s.tiwari0019@gmail.com (Shubham R. Tiwari) move from areas of high concentration to areas of low concentration the carbon rich gas will be attracted to the carbon deficient steel. When the carbon is on the surface of the steel some will diffuse into the steel. The carbon deficient gas will then be replaced by the carbon rich gas fairly quickly because of the speed the molecules move in the vacuum. This is an efficient process because the vacuum required is relatively low and the composition of the gas can be well controlled. Vacuum carburizing is also beneficial because of the low amount of oxygen in the carburizing atmosphere. One of the problems with processing of steels is the oxidizing of the steel at higher temperatures. B. Hardening Hardening is a metallurgical and metalworking process used for increasing the hardness of a metal. The hardness of a metal is directly proportional to the uniaxial yield stress at the location of the imposed strain. A harder metal will have a higher resistance to plastic deformation than a less hard metal. Hardening is performed to: 1) To increase hardness, wear resistance and ability to cut other materials. 2) To improve strength and toughness. The hardening process consists of heating the hypo-eutectoid steel (%C = 0 to 0.8%) to a temperature 30 to 50 ºC above the Upper Critical temperature. For hypereutectoid steels (%C = 0.8 TO 2.11%) to a temperature 30 to 50 ºC above the Lower Critical temperature. Holding at this temperature for considerable time, to complete phase transformation and sudden cooling in water or oil. When the component is subjected to hardening process in a quenched medium, the outer surface of the component experiences cooling effect immediately compare to core of the component i.e. outer surface produces small grains (martensite) and whereas core remains with large grains (Austenite Phase) i.e. Outer surface is hard and core remains in soft condition. Fig. 1. Phase Transformation vs Hardness Proceedings of the World Congress on Engineering 2017 Vol II WCE 2017, July 5-7, 2017, London, U.K. ISBN: 978-988-14048-3-1 ISSN: 2078-0958 (Print); ISSN: 2078-0966 (Online) WCE 2017