H62 Brass Friction Plug Welding Technology Research

As one of the earliest non-ferrous materials used in human history,copper and copper alloys have excellent properties in electrical conductivity,thermal conductivity and plasticity,and are widely used in mechanical equipment,aerospace and chemical industries.At present,the welding methods adopted for the welding of copper and copper alloy are mainly submerged arc welding,brazing,TIG welding and MIG welding welding methods,but in the welding process,copper alloy will appear porosity and other defects,so the need for copper and copper alloy welding,friction plug welding as a new solid-phase connection technology,there are greater advantages in the welding.This paper on 5mm thick H62 brass friction plug welding experiments,the main research content and results are as follows:In this paper,the response surface analysis was used to establish a response surface model with spindle speed(ω),friction time(T)and downward pressure(H)as the three factors,and the results showed that the significance of the three factors on the tensile strength of the joint was ω>H>T.The predicted optimal process parameters were spindle speed 2144 rpm,downward pressure 1.46 mm and friction time 17.72 s.At this time,the tensile strength of the joint could reach 350.38MPa,which is equal to the actual value of 350.9MPa.Response surface analysis found that the spindle speed has the greatest degree of influence on the quality of the joint,so the study of spindle speed on the impact of H62 brass friction plug weld head,the joint tensile strength increases with the spindle speed,when the spindle speed of 2400rpm joint tensile strength decreases,different spindle speed welded joints fracture there are a large number of tough nests,showing the characteristics of toughness fracture,and the upper layer The most number of tough nests,the size of the smallest,then the optimal toughness.Joint microhardness is a"W"type distribution,the joint upper middle and lower three layers of hardness from top to bottom in descending order.The temperature field of the joint increases with the increase of the spindle speed,and there is a certain temperature difference between the upper,middle and lower layers of the joint.EBSD analysis of the friction plug weld head under optimal process parameters,the upper region of the center of the plug bar of the joint experiences greater thermal cycling with shear friction.,where the grain experienced complete recrystallization,the highest content of recrystallized grains,the lowest grain size and a large number of twin crystals.The lower layer of the plug bar center undergoes strong plastic deformation,the grains are mainly composed of deformed grains,the grain size is slightly higher than that of the upper layer,the twins are covered by large deformation grain boundaries,and only a small number of twins are shown.The upper,middle and lower layers of the friction interface are affected differently,and the grain size of the upper,middle and lower layers is from small to large in the order of upper layer>middle layer>lower layer,and the number of twin crystals gradually decreases from top to bottom,and the number of recrystallized grains gradually decreases,but the number of deformed grains gradually increases.The joint heat machine influence zone and heat influence zone are subject to a small amount of thermal cycling,the grain size does not show significant changes,the number of twin crystals slightly increases compared with the parent material,and the recrystallized grains and deformed grains also slightly increase.Friction plug welding head under the optimal process parameters for electrochemical corrosion experiments,the joint was found to have the strongest corrosion resistance in the heat-affected zone,the corrosion layer surface is the densest,the surface is relatively gentle after pickling,no serious corrosion pits,the heataffected zone corrosion resistance is the weakest,corrosion layer corrosion off the phenomenon,the surface after pickling a large number of "gullies".The final result of different positions of the joint corrosion resistance ranking:hot machine influence zone>plug bar center>parent material>friction interface zone>heat affected zone.DEFORM software was used to numerically simulate the welding process of H62 brass friction plug welding,it was found that the friction interface area of the joint and the lower layer of the plug bar metal flow rate is the largest,the peak temperature of the joint first appeared in the lower layer of the plug bar area,with the welding process of the entire plug bar and friction interface temperature gradually the same.The maximum effective stress of the joint first appeared in the plug hole side,and then moved upward along the plate thickness direction to the shoulder and the plate extrusion near the flying edge area,with the welding process,the effective stress of the joint gradually decreased.The maximum effective strain in the joint appears in the lower layer of the plug bar,and the effective strain gradually increases as the welding progresses.