Study On Microstructure And Properties Of Continuous Drive Friction Welding Of 45#/Q235 Dissimilar Steel

Large scale amusement equipment is often used for parts with certain plasticity,toughness and high strength,while dissimilar steel welding can ensure the relevant properties of parts,which is commonly used to connect 45# shaft pin and Q235 profile.Due to there are differences between 45# steel and Q235 steel material properties,the properties of welded joints are poor and defects are easy to appear.Continuous drive friction welding is a solid-state welding,which is an effective method for welding dissimilar steel.In this paper,based on 45# steel and Q235 steel are taken as the research object,through the combination of experimental analysis and numerical simulation,the optimal process parameters of continuous drive friction welding of 45#/ Q235 dissimilar steel are determined.The microstructure,properties and fracture morphology of the joint are studied,and the temperature distribution and material flow in the welding process are analyzed.The details are as follows:The results show that the optimal process parameters of 45#/Q235 dissimilar steel CDFW are rotation speed of 2500r/min,friction pressure(forging pressure)of 40 k N,friction time of 5s,forging time of 2s,maximum joint tensile strength of 491 Mpa,maximum joint hardness of 259.8Hv;under short friction time and low friction pressure,the joint grains are mainly large ferrite and pearlite,with the increase of friction time and pressure,the grains in weld zone are refined by dynamic recrystallization,and the grains are composed of widmanstatten,troostite and pearlite.The grains in partially deformation zone grow up endothermically,and only part of recrystallization refinement occurs.With the increase of friction time and pressure,the grains in the joint grow endothermically.The hardness of the joint presents an inverted "V" shape,the hardness near the weld zone is higher than other zones,the fracture position of the joint was located in partially deformation zone of Q235 steel,there are dimples at the fracture,and the fracture form is mainly ductile fracture.With the increase of friction time and friction pressure(forging pressure),the maximum temperature and material flow velocity of the joint first increased and then maintained at a stable value;the maximum temperature and material flow velocity of the joint first appeared in the 0.5R zone,and with the increase of friction time and friction pressure(forging pressure),the maximum temperature and material flow velocity continuously extended to the edge zone and R zone until the whole weld line.The temperature and flow velocity of the newly formed flash are high,and the temperature and flow velocity of the formed flash decrease rapidly;the material on the axis mainly moves along the axial direction;under the condition of short friction time and low friction pressure(forging pressure),the material in R zone mainly moves along the axial direction,and the material in 0.5R zone and edge zone moves along the axial direction and radial direction,the material of flash mainly came from 0.5Rand edge zone.Under long friction time and high friction pressure(forging pressure),the material of three zones moves along the axial and radial direction,and the material of flash mainly came from three zones.