Tham khảo tài liệu 'modeling and simulation for material selection and mechanical design part 6', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Figure 2 The specimen and sheathed thermocouples. Figure 3 The carburizing-quenching process. 2. Models of Simulation The simulation model in carburizing-quenching process is a steel cylinder of 20 mm diameter 60 mm length and carbon. It is assumed that the model is located in a uniform coolant. Then the finite element model belongs to an axisymmetrical problem. As an initial step of the heat treatment process calculations for the heating and carburizing process were used to simulate thermal stress field thermal distortion as well as carbon distribution in the model. The quenching process of the model was started from the initial temperature 850 C and the model was cooled to 30 C with oil. The heat transfer coefficients h during quenching were calculated as a function of temperature by the methods mentioned below and were used for the simulation as the surface boundary condition in Eq. 4 . 3. Identification of Heat Transfer Coefficients It is important to determine the heat transfer coefficients in the quenching process of metal parts for numerical simulation. However it is rather difficult to evaluate heat transfer coefficients during quenching of actual steel Copyright 2004 by Marcel Dekker Inc. All Rights Reserved. parts which depend on not only the quenchant but also the shape size surface condition and thermal properties of parts etc. It is therefore very difficult to evaluate the heat transfer coefficients in quenching of steel parts. Some approximate methods are estimating the coefficients from the cooling curve data of standard probes which are used for evaluation of the cooling power of liquid quenchants. We have already reported the availability of the lumped-heat-capacity method for the estimation of the heat transfer coefficient from the cooling curve data of the JIS silver probe pure silver solid cylinder of 10 mm diameter by 30 mm length Japanese industrial standard K 2242 72 which has a high thermal conductivity. A computer program LUMPPROB .
