| With the development of the automobile industry, the car Radiator constantly is upgrading, Used in the manufacture radiator of copper with products quality is also increasing. And Our country’s automobile tank with thin copper production technology is not high, mainly for the dimensional accuracy of the control level is not high, the performance needs to be improved uniformity.In this paper, micro-alloyed copper alloy prepared by atmospheric melting method, single trace amounts of Ni, Sn, Cr, Zr elements are added to pure copper. Through experiments to study the effects of four elements on the microstructure and properties of copper, conclusions are as follows:(1) when melting, Ni and Sn is added in the form of pure metal, Cr and Zr is added in the form of master alloys. The Strength and hardness of alloy are increases, but the conductivity is decreased. Trace amounts of Ni, Sn, Cr and Zr element have varying degrees of improvement on Softening resistant performance of copper. Softening temperature of Cu-0.25 Ni is 395℃; Softening temperature of Cu-0.25 Sn is 440℃; Softening temperature of Cu-0.25 Cr is 460℃; Softening temperature of Cu-0.25 Zr is 475℃.(2) Trace amounts of Ni, Sn, Cr and Zr element have varying degrees of improvement on Corrosion resistant performance of copper. the corrosion rate decreased from 0.0367mm/a of Cu-0.05 Ni to 0.0267mm/a of Cu-0.25Ni; 0.0241mm/a Cu-0.05 Sn of is reduced to 0.0186mm/a of Cu-0.25Sn; 0.0299mm/a of Cu-0.05 Cr is reduced to 0.0256mm/a of Cu-0.25Cr; 0.0344mm/a of Cu-0.05 Zr is reduced to 0.0299mm/a. of Cu-0.25 Zr.(3) The best aging treatment of Cu-0.2Cr alloy is 450℃×4h, the hardness is 87.8HB, the conductivity is 85.7%IACS; the best aging treatment of Cu-0.2Zr alloy is 450℃×2h, the hardness is 86.8HB, the conductivity is 86.5%IACS.(4) Welded joints hardness of the weld centerline symmetrically, Weld hardness is the lowest, The farther away from the weld center, the higher the hardness. The weld heat-affected zone width of Cu-Ni alloy from the centerline is 5~55mm, There are lots of porosity in weld, Tensile strength of welded joints is 150 MPa, Weld strength is only 38.3%; The weld heat-affected zone width of Cu-Sn alloy from the centerline is 5~40mm, Tensile strength of welded joints is 215.3MPa, it can reach 53.7% of the base material; The weld heat-affected zone width of Cu-Cr alloy from the centerline is 5~25mm, Tensile strength of welded joints is 189 MPa, Reached only 46.9% of the base material; The weld heat-affected zone width of Cu-Zr alloy are narrowest, It is away from the center line of 5~15mm, the tensile strength of welded joints is 185 MPa, reached only 44.3% of the base material.(5)Comparing the experimental results of these four elements, Finally, the selected elements are added Sn, Sn addition amount range: 0.14~0.16%, The tensile strength is 425 MPa, Conductivity is higher than 90%IACS, Corrosion rate 0.01892mm/a, Softening resistance temperature is 425℃, It meets the requirements of the tank Copper strip, Through the research on the alloy melting and casting process, developed a complete set of smelting casting process is:Casting temperature:1160~1185℃;Casting process parameters:6.2mm/0.62 s-1-2.0s-1.2mm/0.2s-0.2s,Casting speed:100~140mm/min;Casting mold water pressure: 0.4 ~0.7MPa.(6) Developed a high-precision ultra-thin copper strip rolling, annealing, and plate-type control technology.The main rolling process for roughing: 14.5-12.0-9.1-6.0-3.8-2.0-1.4, the rolling: 1.4-0.9-0.6-0.45,pre-finishing:0.45-0.25-0.18-0.13-0.1,finishing:0.1-0.085,0.1-0.075,0.1-0.07-0.05.Bell furnace annealing process: the thickness of 1.4mm, the annealing temperature is 400℃, insulation 6h;Continuous annealing process: the rolling intermediate annealing temperature is 650℃, annealing speed is 39m/min; pre-finishing annealing: temperature is 450℃, annealing speed is 95/min.The thinnest of Strip Thickness is 0.05 mm, thickness tolerance is ± 0.003 mm, rolled plate can be controlled within 10 I. |
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