Study On The Friction Welding Of Light Truck Bridge Shaft Tube

Continuous friction welding is a new type of welding technology which is efficient,low-cost,non-polluting and can be used for batch operations.At present,it is widely used in aerospace and automobile manufacturing fields,and is especially suitable for the connection of column-type workpieces.Compared with other welding methods,there is no chemical reaction at the friction welded joint,mainly for forged structure.Therefore,the defects of pores,segregation or cracks are relatively small,and the joint strength is much stronger than that of fusion welding and brazing,and can even exceed the strength of the base metal.Our light truck bridge is a form of butt welding of the shaft tube and the shaft head.In the early stage,the carbon dioxide gas shielded welding form of the opening groove is adopted,and the shaft head and the shaft tube are made of Q420 low carbon alloy steel.In order to improve work efficiency,our company newly introduced the shaft friction welding machine.Due to the lack of theoretical support,during the debugging process,the influence of various welding parameters is not understood,and the detour is repeated many times.In order to facilitate the promotion of the friction welding process in the future,the friction welding mechanism was further studied by the company's debugging opportunities.In the actual research,through the literature analysis method,the research results of the previous application of the friction welding process are summarized.Through the test verification method,the weld performance is judged by hardness test,tensile strength and metallographic analysis;Software,establish a friction welding shaft head flash model,and study the influence of welding parameters on the flash.According to the general procedure of the welding test,9 specimens were prepared by M125 double-head friction welding machine,2 of which were subjected to the failure test to prepare the metallographic test,and the metallographic analysis,hardness analysis and analysis of the welded joint were carried out.The influence of each parameter on the joint,and the non-destructive testing of the remaining 7 joints,the weld quality is guaranteed to be no problem.The test results show that the martensite is formed in the weak part of the weld fusion zone and the superheat zone,resulting in increased hardness and brittleness,which is the weakest link of the weld.At the same time,the friction time is short and the top section Under the large pressure and large secondary friction pressure,the weld microstructure is more uniform;the non-destructive testing results show that the friction welding quality is relatively stable.Through the simulation of the friction welding weld flash,it is found that different process parameters correspond to different flash edges,so the foreign trade of the flash can be used as a reference for determining the quality of friction welding.The friction welding of the shaft head friction mainly occurs after the welding process reaches the steady state.The metal material near the interface of the friction welding interface flows out of the interface and forms a flash edge,and the size of the flash edge increases with the increase of the welding time,increasing the axial pressure.It is easier to form a large-sized and highly curved burr than to increase the initial rotational speed.The welding is preferably performed at an initial rotational speed of about 400 r/min and an axial pressure of about 800 KN,at which time the flash is about 9 mm.