Design And Research Of Pulsating Aging Heating System For 2219 Thick Plate Friction Stir Weld

2219 aluminum alloy has excellent strength and low temperature performance,and is widely used in aerospace rocket tanks.However,as China has stepped from a large Aerospace country to a first-class aerospace power,it has put forward higher requirements for the welding strength of the fuel tank of the Long March 9 rocket with a diameter of 9.5m.Therefore,aging treatment of the tank to further improve the welding strength is the development trend of friction stir welding of thick aluminum alloy in the future.However,at present,there is no relevant control technology and aging furnace equipment,and the control technology and aging furnace equipment to achieve spatial uniformity and time synchronization of temperature rise in a super large scale;At the same time,the overall aging will also over age the non welded area of the base metal outside the welding area during weld strengthening,reducing the overall performance.In view of the above problems,the new process and test system of weld induction heating pulsating aging strengthening are studied in this paper.The main research work and progress are as follows:(1)The moving induction heating model of 2219 aluminum alloy thick plate weld was established.The temperature field distribution of aluminum alloy thick plate weld heated under different frequency,current and moving speed was simulated,and the effects of different frequency,current and moving speed on the temperature distribution of aluminum alloy thick plate weld surface and thickness direction were discussed.The analysis shows that it is feasible to apply induction heating method to pulsating aging heating of thick plate welds.The effects of different frequency,current and moving speed on the temperature distribution on the weld surface and thickness direction of aluminum alloy thick plate were discussed.After optimizing the parameters,the upper surface temperature of the aluminum alloy is 172℃,and there is still 140℃at 10mm in the thickness direction,which meets the requirements of pulse aging heating.(2)According to the design of relevant process parameters optimized by reference numerical simulation,an induction heating pulsating aging system is built.The induction heating pulsating aging system includes induction heating equipment,infrared temperature measurement system,temperature control system and linear reciprocating motion platform.The system can well realize the pulsating aging heating of the friction stir weld of thick aluminum alloy plate.The temperature error is about±3℃,and the temperature of 36mm thick aluminum alloy plate can reach 170℃after 30s heating..The temperature time curve of the upper surface of the induction heating aging weld is measured by K-type thermocouple experiment,and the trend is basically consistent with the temperature time curve of the numerical simulation,which verifies the accuracy of the numerical simulation model.(3)By comparing the microstructure and mechanical properties of friction stir welded joints under induction heating pulsating aging,continuous aging and welding,the feasibility of the induction heating pulsating aging system was verified.The results show that compared with the as welded joint,the grain size and shape of the stir welded nugget zone,the heat engine affected zone and the heat affected zone of the continuously aged 6h and the induction heating pulse aged 6h welded joint have no obvious change;However,the second phase of the heat affected zone and the heat affected zone have different degrees of growth.At the same time,both continuous aging and induction heating pulsating aging promote a large number of weld agitation zonesθ~′Re precipitation process of phase,The former ofθ~′is larger than the latter in the number and size of phases,but it is not obvious.Continuous aging and induction heating pulse aging have positive effects on the mechanical properties of the joint.The tensile strength of the welded joint after continuous aging and induction heating pulse aging reached 362mpa and 366mpa respectively,while the tensile strength of the welded joint as welded was 337mpa.There are 69 figures,3tables and 73references...