Study On Aluminum Bronze Electroslag Remelting Process And Microstructure And Properties

Electroslag remelting technology is a metallurgical method that combines metal smelting and casting.It has been widely used in the refinement of ferrous metal and alloy because it processes the advantages of reducing non-metallic inclusions and macrosegregation,and improving their mechanical properties.An inspection of literature shows that Electroslag remelting is rarely used in the field of non-ferrous metal and alloy.Especially,its application in refining aluminum bronze has not been reported.Aluminum bronze has good mechanical properties and wear resistance and corrosion resistance.However,due to the problems of complex structure and shape of the copper alloy castings and large differences in solidification of the castings,the mechanical properties of the casting body are lower than those of the copper alloy samples.In this paper,it is hoped that the aluminum bronze can be refined and solidified by electroslag remelting to obtain aluminum bronze with uniform microstructure and high purity,which further improves the mechanical properties and corrosion resistance.According to the characteristics of aluminum bronze melting process and the adaptability requirements of melting point,density,viscosity,electrical conductivity and surface tension of remelted slag,I designed 38% CaF2+57%NaF+5%Al2O3 slag system for aluminum bronze.We prepared ZQAl9-4 alloy ?60×1470mm fused cast electrode rod by ordinary casting process.The crystallizer used for electroslag remelting has an inner diameter of 116 mm,an outer diameter of 246 mm and a height of 460 mm.The electroslag remelting ingot is prepared under the condition of a current of 2000 to 2500 A and a voltage range of 40 to 42 V.The amount of slag was about 1.7kg.XRD phase analysis,metallographic microstructure and scanning electron microscopy analysis of the alloy samples and the anatomical samples of the bearing castings before and after the electroslag casting process.After the electroslag remelting,the aluminum bronze grains were remarkably refined,and the grain size was reduced by about 50% before melting.The number of ? phase and the ?2 phase decrease,the needle-like ?? phase increases,the precipitated phase ? is refined and well-distribute,and the internal structure segregation is significantly improved.Compared with the sand casting electrode sample,the grain boundary of the remelted ingot is more complete,and the precipitation phase near the grain boundary is more.The mechanical properties test of aluminum bronze samples under different process conditions shows:The average hardness of aluminum bronze before and after electroslag remelting is basically flat,but the hardness of remelted ingot is more uniform;the tensile strength of the remelted ingot reaches 620 MPa,the yield strength is 180 MPa,the elongation is 19.5%,and the impact energy is 25.2J,the performance of the pre-melting electrode rods increased by 18%,12.5%,13.4% and 68% respectively;the performance of the electrode rod before the specific gravity is increased by 18%,12.5%,13.4% and 68% respectively.The toughness and toughness of the alloy after remelting are obviously improved.The friction and wear test analysis shows that the aluminum bronze wear rate after electroslag remelting is reduced by nearly 50% compared with the consumable electrode and the bearing body of the bearing,and the durable performance of the remelted ingot is improved.Through the analysis of the comprehensive corrosion in the South China Sea and stress corrosion test in seawater,the corrosion loss of ZQAl9-4 aluminum bronze decreased by 44%,the corrosion rate decreased by 7.5%,and the area of corrosion pit of the corrosion surface decreased by 58%.After electroslag remelting,the alloy has a rupture time of 19.5 hours at a slow strain of 0.006 mm/min under seawater conditions,fracture strength is 443 MPa,elongation is 12.8%.The stress corrosion resistance of the electrode before the specific gravity is increased by 156 %,56% and 128%,the electroslag remelting process improves the seawater corrosion resistance of the alloy.