Experimental Research On Contact Heat Transfer Between Die Material And Super Alloy/Titanium Alloy

During precision forging process of super alloy and titanium alloy,the contact heat transfer has an impact on the accuracy of the component and tool-life.Thermal contact conductance(TCC),as an important physical parameter affecting the distribution of temperature field,is of increasing interest to researchers and engineers.Numerical simulation is one of important methods used in the prediction of hot working.The reliability of analytical approaches depends on the accuracy of material properties and physical parameters.One of important parameters which characterize thermal state of the forged blank is the TCC.So it is necessary to test the TCC and find the affecting factors.Mechanism of contact heat transfer is very complex.Although there are various theoretical models,the application of analytical models to the prediction of TCC is still not feasible as several affecting factors are not considered,and many assumptions are used.The present work concentrates on the measurement of the TCC between the tool and the work piece during forging processes.The main work in this subject is embodied as follows:1.An experimental study which investigates the TCC of die steel and titanium alloy surface in forging environment is described in the range of 500-800℃.The relationships between TCC and average interfacial temperature,contact pressure,thickness of the glass lubricant,contact process were analyzed respectively.2.Glass lubricant enters a liquid state in the temperature range of 620-740℃.The thermal conductivity of glass lubricant increases with the increasing temperature in the range of 510-636℃.3.Various basic reviews,methods and mathematics models about interfacial heat transfer had been summarized.A TCC model for interfaces with interstitial materials was presented based on the testing data and the former authors' models.