Processing Technology And Interfacial Characteristics Of Stud-type Spin Impact Bonding

In modern industry,it is widely required to join columnar metal and plate metal.Traditional methods of welding column-plate structural parts include arc stud welding,friction stud welding and resistance stud welding.The above three welding methods have different degrees of limitations in application.Impact bonding can achieve better solid-phase connection between dissimilar materials.Common impact bonding include explosive welding,magnetic pulse welding,and capacitor discharge welding.The main application of explosive welding is composite with large-area plates,magnetic pulse welding is applied more on pipe composites,while capacitive energy storage welding is concentrated on bonding of small parts.Given the current common impact bonding method is not good enough to meet the requirements of column-to-plate structural parts dissimilar materials welding,this study developed a new impact bonding method,stud-type spin impact bonding,using guns to launch homemade pure copper bullet to hit the low carbon steel plate,and the collision speed is controlled by controlling the amount of the gunpowder,and the solid phase connection between the dissimilar materials of the column-plate structural member was achieved.This research mainly includes the process characteristics of stud-type spin impact bonding,the relationship between the interface wave and reliable connection,the interface microstructure and the deformation of the grain deformation,and the theoretical verification of the interface forming and deformation.The part of process characteristics mainly studied the shear deformation of the collision surface and forming characteristics under different impact ways,the results shown that the tile angle between the stud and the steel plate is necessary.The forming characteristics of stud-type spin impact bonding include the height of the stud bump,the edge diameter after the stud collision deformation,the diameter of the collision area,the diameter of the indentation,the depth of the indentation,and the height of the edge of the warp.When the bullet speed increases,the height of the stud edge will decrease,the diameter of the edge after the stud collision will increase,the diameter of the collision area will not change significantly,the diameter of the indentation will increase slightly,and the indentation will increase.The edge height will increase.The part of relationship between the interface wave and the reliable connection summarizes and discusses the formation mechanism and influence mechanism of the implant-type rotating collision impact interface.It was found that the wavelength and amplitude of the interface wave increase with the increase of the collision velocity and the collision angle.In addition,it was verified by bending and tearing experiments that the joint formed by the wave-shaped interface has better tear resistance.Besides,the hardness distribution of the interface was analyzed by nanoindentation test,it was found that the hardness of the Fe side near the collision interface increased,while the hardness of the Cu side near the collision interface decreased,and the hardness at valley is smaller than the peak.The wavelength and amplitude of the generated interface wave were measured,the results shown that the farther from the center line of the stud axis,the larger the amplitude and wavelength of the interface wave with smaller collision angle.The part of relationship between the microstructure and grain deformation of the interface is mainly carried out by observing the microstructure changes near the collision interface via SEM,the results shown that there is residual austenite on the Fe side after the collision,and deformation of the crystal structure and slip on the Cu side.In addition,the evolution of grain deformation along the direction of collision and the direction perpendicular to the collision interface to the depth of the base metal parallel to the collision interface of Fe and Cu were analyzed,it is found that the wavelength and amplitude of the interface wave at the front collision end are larger and the grains will break and stretch in the direction of collision.In the vicinity of the collision surface,the grain refinement was obvious,and as the collision velocity increases,the grain refinement effect enhanced.As the collision progresses,the wavelength and amplitude of the interface wave at the collision interface are greatly reduced.At this stage,the grain is still stretched along the collision direction.At the end of the collision,the grains on the side of the steel plate is only slightly stretched,and further extends along the collision surface toward the base material,the grains were refined into equiaxed crystals,and in the deeper material,coarse-grain-like grains are formed along the direction of the collision.In the part of theoretical verification of interface forming and deformation,ANSYS LS-DYNA was used to do a numerical simulation of the impact between the stud and the steel plate.The equivalent stress,the stress components at the center of the impact surface and the deformation evolution of the stud and the steel plate during the collision process were analyzed.The results shown that the equivalent stress on the surface of the steel plate is symmetrically distributed and will become uniform with the collision,while the stud and steel plate tilting collisions create a more pronounced broadening in the rear collision zone.