Study On Aluminium Shot And Zinc Shot Used For Blast Cleaning

Aluminium cut wire shot and aluminium alloy cut wire shot collectively referred to as aluminium shot,zinc cut wire shot and zinc alloy cut wire shot collectively referred to as zinc shot.As metal abrasives for blast cleaning of castings,die castings,forgings and profiles of aluminum,zinc,magnesium and its alloys,it has been widely used in the automotive,motorcycle,high-speed rail,aviation,instrumentation,hardware and other industries.Aluminium shot and zinc shot used for blast cleaning can effectively remove oxide scale,sticky sand,burrs and debris on the surface of the workpiece,providing a high-quality surface for subsequent passivation,painting,plating and rust prevention of the workpiece.This paper mainly studies the properties,blast cleaning,wear failure process and finite element simulation of blast cleaning of aluminum shot and zinc shot.For properties studies,Ervin life of shot is measured by Ervin life testing machine;measured of microhardness of aluminum cut wire shot and aluminum alloy cut wire shot after different impact cycles to characterize their work hardening characteristics;The metallographic microstructure of aluminum shot and zinc shot was observed and their change rules were analyzed.For blast cleaning studies,Ervin life testing machine simulates the blast cleaning equipment working process to clean aluminum plates and aluminum alloy plates,study on the cleaning efficiency and surface roughness of aluminum shot and zinc shot cleaned up to 98%coverage under the same mass and same volume conditions,optical profiler to observe the surface profile after cleaning,thus,the effect of blast cleaning of aluminum shot and zinc shot is compared.For wear failure process studies,determination of the relationship between impact cycles and residual mass,scanners were used to scan the appearance of shot during wear failure,and the morphology of shot after wear failure was observed with scanning electron microscope,then,analysis and discussion of its wear patterns and failure forms.For finite element simulation studies,using ABAQUES finite element software,a finite element model and a simulated roughness algorithm were established,the accuracy of the model and algorithm was verified by comparing the simulated value with the experimental value,the surface roughness at different shot speeds was simulated and the variation law was characterized.The results show:in the properties,aluminum cut wire shot and aluminum alloy cut wire shot undergo plastic deformation during the continuous impact cycles,the crystal grains are continuously refined,and the dislocation density continues to increase,resulting in work hardening and increased hardness.Its metallographic structure is the streamlined and broken grains after drawing.Zinc cut wire shot and zinc alloy cut wire shot have low recrystallization temperatures and recrystallize in the process of production and impacting.So it is no work hardening feature and its metallographic structure is equiaxed grains.The Ervin life of aluminum cut wire shot and aluminum alloy cut wire shot is much greater than that of zinc cut wire shot and zinc alloy cut wire shot.In the blast cleaning,aluminum cut wire shot and aluminum alloy cut wire shot cleaning efficiency are higher than zinc cut wire shot and zinc alloy cut wire shot,and surface roughness are smaller than zinc cut wire shot and zinc alloy cut wire shot in the same mass and the same volume conditions.With the increase of the particle size of the four types of shot,the cleaning efficiency gradually decreases,and the surface roughness gradually increases.The cost factor of aluminum cut wire shot and aluminum alloy cut wire shot is much smaller than that of zinc cut wire shot and zinc alloy cut wire shot.In the wear failure process,the wear process can be divided into three stages:passivation rounded stage,stable wear stage and severe wear stage.In the passivation rounded stage,the shot shape changes from a cylinder to a sphere;in the stable wear stage,the shot shape basically does not change in size,aluminum cut wire shot and aluminum alloy cut wire shot have a longer stage;in the severe wear stage,there are cracks in the shot and a large number of broken small shot.The main types of wear failure include adhesive wear,skin breakage and fracture breakage.Aluminum cut wire shot and aluminum alloy cut wire shot are mostly ductile fractures.The fracture surface has a smooth surface of the shear lip and a dimpled fiber area.Zinc cut wire shot and zinc alloy cut wire shot have mostly broken cores.In the finite element simulation of blast cleaning,the simulated value is consistent with the experimental value,which proves that the established finite element model and simulated roughness algorithm are correct and effective.The surface roughness under different shot velocities is simulated.It shows that the greater the speed,the greater the surface roughness,but the increase rate is reduced.