焊接氧化皮对奥氏体不锈钢孔蚀性能的影响

采用电化学测试技术,在NaCl介质中焊接氧化皮对3种奥氏体不锈钢的耐孔蚀性能进行了探讨.结果表明,有焊接氧化皮部位较比母材更易产生孔蚀,去除氧化皮则改善耐蚀性能.有焊接氧化皮的不锈钢耐孔蚀性能依NK1<316<304次序变劣.通过表面SIMS分析,发现焊接氧化皮合金表面贫乏铬,从而导致耐孔蚀性能下降.有焊接氧化皮NK1不锈钢耐孔蚀性能之所以优于304不锈钢,是由于表面膜中富集铜元素,并参与了成膜过程,改善了表面电化学行为,增强了表面膜抵抗侵蚀性离子破坏的能力.

EFFECTS OF WELDS SCALE ON PITTING RESISTANCE OF AUSTENITIC STAINLESS STEELS

The pitting resistance for three kinds of austenitic stainless steels with weld scales were investigated by electrochemical technology in NaCl solution. The result showed that the pitting in the area covered with weld scale occurred more easily than in the base metals. After the weld scale being removed by pickling, the same material showed better pitting resistance for all the three stainless steels tested. For the three kinds of steels covered with weld scale, the pitting resistance order was NK1>316>304. The secondary ion mass spectroscopy (SIMS) analysis indicated that the depletion of chromium made the pitting resistance of the steel covered with scales worse. However, the NK1 covered with weld scale had better pitting resistance than that of the 304 stainless steels because copper element was rich in surface film and took part in the process of film forming, which improved the electrochemical behavior and strengthened it's resistance.