Research On Annealing Microstructure And Properties Of Thin-walled Copper Tube

Thin-walled copper tube having excellent thermal conductivity, anti-magnetic corrosion resistance, good mechanical properties and ductility,which can be used as an excellent heat transfer device and be widely applied. Multi-pass drawing thin-walled copper tube in the production process leads to work hardening, poor plasticity, is not conducive to late-bending process. A reasonable choice of finish annealing process on the final product performance is critical.The microstructure and properties of defective TP2 brass thread were detected,and contrasted with the licensed tube’s. Testing found that the grain size of the defective TP2 brass thread were higher than the normal management of large and uneven organization, higher hardness values than normal tube’s, the grains’ orientation factors in the (111) plane was higher than normal tube’s, while lower than normal tube’s in the (220) plane.The recrystallization annealing test of TP2 copper tube at different annealing temperatures and holding time were studied, the variations rules of microstructure and properties were analyzed. Annealing results showed with the growth of annealing temperature and holding time, the grain size became larger after recrystallization, the number of annealing twins increased, the hardness value decreased, the grains’ orientation factors in the (111) plane increased; At a heating temperature of 445℃ to 520℃, holding time within the range of 27-39min, The organization of the annealed Φ9 (9.520×0.240×0.120mm) model copper tube satisfied the formula f (d) =0.1510+0.0030t1/2-0.0400e-23316.0930/T, the hardness values satisfied the equation f (H)=340.0000-2.9580t-0.8480T+0.0200t2+0.0030tT+0.0010T2; At a heating temperature of 475℃ to 550℃, holding time within the range of 27-39min, The organization of the annealed Φ7 (7.000×0.250×0.180mm) model copper tube satisfied the formula f (d)=0.0800+0.0040t1/2-0.0140e-23316.0930/T, the hardness values satisfied the equation f (H)= 484.3000-3.8350t-1.1690T+0.0400t2+0.0010tT+ 0.0010T2.