Experimental Study On Portevin-Le Chatelier Effect Of Aluminum-magnesium Alloy Based On Heat Source Analysis Method

It is remarked that some plastic instability phenomena such as Portevin-Le Chatelier(PLC)effect may occur in the Aluminum magnesium alloy in the process of processing and service,which may bring unexpected surface roughening effect and lead to the weakening of material structure stability and even premature failure in some most unfavorable cases.Traditional PLC effect research focuses on laser scanning extensometer and digital speckle interferometry,but the two methods have their own limitations.Therefore,a method of heat source analysis is introduced into the study of PLC effect in Aluminum magnesium alloy.The main work is as follows:(1)A method for calculating full field heat source of alloy material under tensile dynamic damage is presented.Firstly,a full field temperature measurement platform based on advanced infrared thermal imaging technology is constructed,to lower the environmental noise,an insulation set-up was designed and placed around the specimen.Then,based on the theory of thermodynamics,heat conduction equations under tensile dynamic loading are derived.According to this method,heat source fields under tensile tests can be obtained accurately.(2)Based on the heat source analysis method,the evolution of thermal dissipation of PLC effect under different tensile strain rates is studied.Using this method,the accurate temperature field obtained from experiment is imported into heat source calculation model to acquire accurate heat source field.Then,the evolution of heat source field accompanying with PLC effect under different strain rates is studied,the A,B and C PLC bands were obtained.(3)The relationship between thermal dissipation and microstructure evolution of the specimen surface in the process of PLC effect is investigated.The evolution of microstructure analysis under different strain rates was carried out by an in-situ fatigue testing machine.Based on dynamic strain aging(DSA),the microstructural evolution and its qualitative relationship with temperature evolution are analyzed,which lays the foundation for further study of the micro mechanism of PLC effect...