Numerical Investigation On Induction Heat Treatment And Research On Rapid Austenization Kinetics

Due to the high heat efciency, high heat rate, convenience of automation andother advantages, induction heat treatment has been widely used in auto parts, bear-ing and other parts’processes. Computer simulation of induction heating process cannotonlygetinformationofelectromagnetic, temperatureandsolidstatetransformationfelds, but also can reduce experimental cost, provide guildlines for process optimiza-tion and coil design. However, a complete set of numerical simulation work includingelectromagneticfeld,temperaturefeldandsolidstatetransformationandexperimentalverifcation has not been established both in China and abroad.First, this thesis is focused on transformation kinetics of rapid austenization dur-ing induction heat treatment. After a brief review of the JMAK dynamics model, thisthesis describes a newly developed extended analytic dynamics model which is basedon JMAK. Subsequently proposed a new kinetic parameters determination formulasand an iterative approach; the same time, the success of the chaos particle swarm opti-mization algorithm is applied to numerical ftting of kinetic parameters determination.Based on42CrMo steel austenitic dilation data, this thesis used these two methods todetermine the kinetic parameters, the parameters describes the dynamics characteris-tics consistently with the experimental values.Second, this thesis also use a fnite element model to simulate the induction heattreatmentprocessofacylindricalworkpiece. Combinedwithkineticresults,thismodelpredictsthechangesofelectromagneticfeld, temperaturefeldandtransformationpro-cess. Experimentally obtained temperature curve, the microstructure distribution andhardness results is very close to temperature changes and phase distribution informa-tion obtained by simulation which confrms the validity of the model of the present simulation.The comparison results prove that the numerical simulation method and kineticapproach has the ability to predict the temperature change under real process, and laythe foundation for further exploration of computer numerical simulation of inductionheat treatment.