加工工艺对无铅黄铜耐腐蚀性能的影响

Effects of Processing Techniques on Corrosion Resistant of Pb-free Brass

采用脱Zn腐蚀深度测量方法、恒电位测试方法、光学显微镜和SEM等分析方法,研究了不同的加工工艺对无铅易切削铋黄铜的耐脱Zn腐蚀性能的影响。结果表明,冷拔态的铋黄铜,由于β相沿着冷加工方向分布,同时位错密度和残余应力的增加,导致了其耐脱Zn腐蚀性能比热轧态的黄铜和铸造态的黄铜差。热轧态的黄铜,由于在热加工过程中发生了回复和再结晶,使得其耐腐蚀性能和铸造态的相当。黄铜在3%的NaCl溶液中会生成Cu2O、CuCl钝化膜,产生钝化现象,极化测试表明冷拔状态无铅黄铜产生点蚀现象。

Effects of different processing techniques on corrosion resistance of Pb-free brass have been investigated by dezincification corrosion depth testing, potential tests, optical microscope and SEM. The results show that dezincification corrosion resistance of cold-drawing Bi-brass is worse than that of hot-rolled Bi-brass and as-cast Bi-brass as a results of β phase distributed along cold-working direction and the increase of dislocation density and residual stress. The corrosion resistante of hot-rolled Bi-brass is equivalent to that of as-cast Bi-brass, which is attributed to the dynamic recovery and recrystallization during hot-rolling process. The passivation phenomenon of the brass in 3% NaCl solution can be observed due to the creation of passive film of Cu_2O or CuCl_2. Occurrence of pitting corrosion in cold-drawn brass can be found after the polarization measurement.