酸性NaCl溶液中304控氮不锈钢腐蚀过程的声发射特征

采用声发射技术和电化学噪声技术研究了304控氮不锈钢C型环试样在0.5mol·L-1NaCl与1.5mol.L-1H2SO4的混合溶液中,恒载荷情况下的腐蚀过程。分析了腐蚀过程中所产生的声发射信号的振铃数随时间分布情况,以及不同阶段的声发射信号的频谱特征。同时对比分析了声发射检测结果与电化学噪声检测结果。结果表明,声发射检测技术对于304控氮不锈钢在酸性NaCl溶液中所产生的腐蚀声发射信号很敏感,在不同腐蚀阶段中,声发射信号特征差异明显,对于判断不同腐蚀阶段具有指导意义;声发射与电化学噪声测试结果基本一致,将声发射检测与电化学噪声检测结合使用,有助于使现场检测结果更加可靠。

Acoustic emission characteristics of corrosion process of 304 nitrogen controlled stainless steel in acidic NaCl solution

The corrosion behavior of 304 nitrogen controlled stainless steel C-ring specimen with constant load in acidic NaCl solution is studied using acoustic emission(AE)and electrochemical noise(EN)techniques.The solution contains 0.5 mol·L~(-1) NaCl and 1.5 mol·L~(-1) H_2SO_4.The ring-down count feature of each AE signal generated during the corrosion process is extracted.By analyzing the ring-down count distribution as a function of time,it is found that the ring-down counts are significantly different in different corrosion stage,which may be used to estimate different stages of corrosion process.The frequency spectrum of AE signal at each main stage is analyzed.The stress corrosion cracking(SCC)of specimen is detected by using AE and EN techniques and the acquired data are compared.The result shows that AE technique is very sensitive to the AE signals generated by 304 nitrogen controlled stainless steel in acidic NaCl solution,so that the corrosion can be detected effectively.The test result of AE is consistent with that of EN,and the combination of AE and EN techniques makes the on-site testing more reliable.