Numerical Simulation Of The Heat Treatment Process Of S34MnV Steel Main Neck For Ship

Large marine crankshaft is an important part of marine engine,it consists of two parts: the main journal and the crank.Main journal is one of the most important and expensive parts of the entire engine.Main journal will be out of shape by internal stresses during the heat treatment process.A damaged main journal can cause damage to other parts of the engine,rendering the engine inoperable,and its stability greatly affects the reliability of the entire engine.Therefore,manufacturing processes of large-scale main journal must meet the strict requirements of standard specifications.With the development of science and technology,simulation technology is becoming more and more mature,it has been widely used in the design of engine parts.The main journal is made of S34 MnV steel in this paper.In order to obtain the results of multi-field coupled simulations,it is necessary to quantify the effect of stress on phase transition kinetics and transformation plasticity and derive a corresponding mathematical model.In this paper,the marine journal,the development of numerical simulation of heat treatment process at home and abroad and the calculation model principles of heat transfer,microstructure and stress are briefly introduced.Expansions of martensite transformation in S34 MnV steel are studied under tensile and compressive stresses using a Gleeble-3500 thermo-mechanical simulation system.Such components as elastic strain,thermal strain and transformation strain are extracted from the total strain so as to determine the transformation plasticity coefficient in the Greenwood-Johnson model and the transformation kinetic parameters in the Koistinen-Marburger equation of martensite transformation.The parameters of the physical properties of the S34 MnV steel are calculated using JMatPro software,and the axisymmetric heat transfer model in the quenching process of the main journal is established by the ABAQUS software.In the process of heat treatment,the variation of thermophysical parameters of S34 MnV steel with temperature and the latent heat of phase transformation are taken into account.The relevant program code is programmed in high-level language.In the quenching process,water quenching andquenching alternately by water and air are adopted.The paper give quantitative data on temperature field,microstructures field and stress field at each time.The results show that transformation plasticity coefficient K in the Greenwood-Johnson model has a constant value under tensile stresses and another lower value under compressive stresses.Effects of applied stresses on kinetic parameters ? and Ms in the Koistinen-Marburger model are evaluated and found insignificant.The microstructures obtained by two heat methods is similar,but the water quenching is easy to generate great stresses and break the inside of the workpiece.Therefore,it is better to adopt the way of quenching alternately by water and air.