采用干湿交替腐蚀试验方法，结合电化学测试、锈层截面和腐蚀产物X射线衍射(X-ray diffraction，XRD)分析，研究SO₂质量分数对E690钢在模拟污染海洋大气环境中腐蚀行为的影响。结果表明，海洋大气环境中的SO₂改变了E690钢海洋大气腐蚀的电化学机制，使得极化曲线的阳极分支由弱钝化特征转变为活性溶解特征，阴极分支由氧扩散过程控制转变为氧扩散和析氢反应共同控制，因而大大促进了阳极和阴极的电化学反应过程。同时，SO₂又显著促进α-FeOOH的生成和Ni、Cr合金元素在内锈层中的富集，大大促进锈层的致密化，使均匀腐蚀速率逐渐减低，并促进锈层底部点蚀坑的生长。随着模拟溶液中NaHSO₃浓度的增加，E690钢在60 d内的平均腐蚀速率逐渐增加，当NaHSO₃浓度达到0.03 mol/L时，又出现一定程度的降低;同时，锈层底部的点蚀坑随NaHSO₃浓度的增加显著长大。

In order to investigate the corrosion resistance of ocean platform steel E690 in sea water, the corrosion induced by oxygen-concentration cell of E690 steel in 3.5%NaCl with oxygen concentration within a range of 0.3 to 8 mg/L was investigated by means of electrochemical measurement techniques, scanning electron microscopy and Raman spectroscopy. The influence of the difference in dissolved oxygen, the ratio of cathode area to anode area and the corrosion product on the corrosion behavior of E690 steel was examined respectively. It was found that: when the ratio of cathode area to anode area was less than four (Sc/a≤4), the cathode and these ratios would be the main factor that influenced the oxygen-concentration cell corrosion; when Sc/a>4, the dissolved oxygen would be the main factor that influenced the oxygen-concentration cell corrosion; How the corrosion product influenced the oxygen-concentration cell corrosion depends on the dissloved oxygen. When the rusted metal under an oxygen-deficient condition, the rust layer would prevent the substrate from corrosion; when the rusted metal was immersed in an aerated condition, the corrosion product would participate in the cathodic reaction process, which would accelerate the anode dissolution and resulted in localized corrosion, such as pitting.

With the development of ocean engineering, various metallic materials have been applied to the marine environment. It is an urgent requirement to study the galvanic series and alloy composition optimization of metallic materials in the tropical marine environment. In this work, open circuit potentials (OCP) and galvanic series of 36 kinds of metallic materials in Sanya seawater were studied. By considering the response of OCP to tidal changes, the anti-corrosion effects of alloying elements were also analyzed. The results show that the OCP of metallic materials in Sanya seawater has a large range. The galvanic series order of metallic materials from high to low in Sanya seawater is: nickel alloy, duplex stainless steel, austenitic stainless steel and pure copper, ferritic stainless steel, martensitic stainless steel, copper alloy, low alloy steel, carbon steel, cast iron, aluminum alloy and aluminum anode. Low-carbon high-alloy content carbon steel and high Cr, Ni contents stainless steel have higher OCP. The potential fluctuations of carbon steel with tidal changes involves two phases: (1) under the dynamics control, the OCP of carbon steel is more negative at high tide; (2) under the diffusion control, the OCP is more positive at high tide. The potential fluctuations of metallic materials reflect the effect of the corrosion product film on the change of ionization balance, and metals with less potential fluctuations have better inhibition on ion diffusion. In Sanya seawater, the carbon steel, which has more alloying content and less carbon content, has less potential fluctuations with the tidal changes and has good oxygen diffusion resistance. The potential fluctuations of austenitic stainless steel with tidal changes are less than that of ferritic stainless steel and martensitic stainless steel. After 2700 h immersion, austenitic stainless steel and martensitic stainless steel, which have a higher content of Mo, have more stable OCP. In other words, the corrosion film gets a better corrosion resistance. The OCP of aluminum anode in Sanya seawater environment increases when the oxygen content is brought up. The OCP of Zn-containing or Ga-containing aluminum anode remains relatively stable. Al bronze and T2 copper have less potential fluctuations with tidal changes, and perform good corrosion resistance in Sanya seawater.

对36种金属材料在三亚海水中的腐蚀电位序、腐蚀电位对潮汐变化的响应以及不同金属合金元素成分对耐三亚海水环境腐蚀的作用进行了研究。结果表明,三亚海水环境中金属材料腐蚀电位的稳定区间较大,腐蚀电位序从高到低为：镍基合金、双相不锈钢、奥氏体不锈钢和紫铜、铁素体不锈钢、马氏体不锈钢、铜合金、低合金钢、碳钢、铸铁、铝合金和铝阳极。碳钢电位随潮汐变化的波动在动力学控制下,高潮位时腐蚀电位较负;在扩散作用控制下,高潮位时腐蚀电位较正。金属腐蚀电位在海水中的波动体现了腐蚀产物膜对扩散控制下的腐蚀具有阻碍作用。在三亚海水环境中,低C和高合金元素含量的碳钢对氧扩散抑制作用较好。奥氏体不锈钢的腐蚀电位随潮汐变化的波动远小于铁素体不锈钢和马氏体不锈钢,浸泡2700 h后,含Mo的奥氏体不锈钢和马氏体不锈钢有较为稳定的腐蚀电位,腐蚀产物膜具有较好的保护性。铝阳极在三亚海水环境中的腐蚀电位随海水高含氧量时间的增加而上升,含Ga和高Zn含量的铝阳极材料的腐蚀电位较为稳定。Al青铜和T2紫铜在三亚海水环境中有较稳定的腐蚀电位,并且有较好的耐蚀性。

本文简要地总结了国内近年来在贝氏体相变理论研究方面的主要成果，包括以下方面：①发现钢中的贝氏体超精细结构；②贝氏体表面浮突完全由贝氏体铁素体长大过程中形变产生，单一超亚单元对应的浮突呈帐篷型；③贝氏体铁素体宽面上存在三维巨型台阶，在近NW关系下相变单元宽面接近(335)f，为扩散型界面；④发现钢中贝氏体碳化物在α/γ界面的γ侧形核并向奥氏体内生长；⑤建立了贝氏体激发形核—台阶长大模型，理论计算表明这种机制是合理的，它成功地解释了贝氏体的多层次复杂结构,以及上贝氏体、下贝氏体等不同形态的形成原因等。

The microstructure of X80 pipeline steel welding joint, consisted of Fe₃C and degenerated pearlite, was simulated by carburizing treatment. The effects of Fe₃C and pearlite on the electrochemical properties of bainitic ferrite steel and localized corrosion occurrence regularity in Yingtan soil simulation solution were investigated by scanning Kelvin probe (SKP), scanning vibrating probe (SVP) and local electrochemical impedance spectroscopy (LEIS), combined with immersion test. It is demonstrated that the corrosion potential of degenerated pearlite is lower than bainitic ferrite, and decreases with increasing Fe₃C content. Localized corrosion occurs on the surface of the carburized sample in Yingtan soil simulation solution. The anodic oxidation process is observed to be initiated on the carburized degenerated pearlite, whereas the cathodic reaction involving dissolved H⁺ is on bainitic ferrite, and the anodic current density increases with increasing Fe₃C concentration. As the ion contents of the soil simulation solution doubled, the anodic dissolution of degenerated pearlite increases, and the local impedance of the electrode decreases.

通过对X80管线钢进行固体渗碳模拟焊接接头区域的Fe₃C和退化珠光体组织,采用扫描Kelvin探针(SKP)、扫描振动参比电极(SVP)和局部电化学交流阻抗谱(LEIS)结合浸泡实验分析了Fe₃C和珠光体对铁素体钢表面电化学性能以及在鹰潭土壤模拟溶液中的局部腐蚀发生规律的影响. 结果表明, 退化珠光体组织在空气(湿度为40\%, 温度为22 ℃)中的腐蚀电位低于贝氏体铁素体, 并且随着Fe₃C含量的增加, 腐蚀电位降低; 渗碳试样在鹰潭模拟溶液中发生局部腐蚀,中心铁素体区为整个材料电偶腐蚀的阴极, 退化珠光体和退化珠光体/贝氏体铁素体区为阳极, 随着Fe₃C含量的增加, 阳极溶解电流密度增大；模拟溶液各离子含量成倍增加后, 退化珠光体的阳极电流密度升高, 电化学交流阻抗值降低, 局部腐蚀效应增大.