EFFECT OF DAMNIFICATION IN RUST LAYER ON CORROSION BEHAVIORS OF LOWCARBON BAINITIC STEEL IN THE ENVIRONMENT CONTAINING Cl−

利用电化学、金相、能谱等方法, 研究了低碳贝氏体钢在表面锈层受到不同程度的损伤后, 在含Cl^-环境中的继续腐蚀行为. 实验发现, 低碳贝氏体钢和作为对比材料的低碳钢试样的表面锈层受损伤后, 在继续腐蚀过程中均能很快得到修复. 在损伤程度与继续腐蚀时间相同的条件下, 低碳贝氏体钢的锈层电阻与损伤修复率均高于低碳钢. 低碳贝氏体钢基体/锈层界面的断裂韧性高于锈层本身.在受外界作用时, 锈层不会沿基体/锈层界面彻底脱落从而在基体表面保存残留锈层. 残留锈层能明显促进新锈层在损伤部位的形成. 原有锈层与损伤部位新形成的锈层中Cu和Cr含量接近, 并与钢基体的含量相当.     

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 通过周期性浸润腐蚀试验,研究了组织结构对贝氏体高强钢的耐腐蚀性能的影响。贝氏体高强钢和其退火试样的失重数据表明,贝氏体组织的耐腐蚀性能略优于铁素体和珠光体组织。运用扫描电镜和X射线衍射仪等分析测试手段对耐蚀机制进行了研究,发现两种试样均存在较致密的内锈层和疏松外锈层。两种试样的锈层成分主要是稳定的α-FeOOH和少量的γ-FeOOH组成。贝氏体组织的高强钢的锈层晶体更细小,均匀的组织结构有利于增强钢的耐腐蚀性能。     

The corrosion resistance of ultra-low carbon bainitic steel

The corrosion resistance of ultra-low carbon bainitic (ULCB) steel was compared with a weathering steel 09CuPCrNi through accelerated corrosion tests. The results indicated that the corrosion resistance was almost the same for ULCB and 09CuPCrNi based on the weight loss. It can be seen that the grain refinement did not deteriorate corrosion resistance property. The homogeneous microstructure, lower carbon content and random distributing ∑3 boundary could effectively increase the corrosion resistance of the ULCB steel. The characteristics of the rust layers indicated that the inner rust layer contained nanocrystalline Fe_3−xO₄ particles, while copper and chromium alloying additions were enriched at the rust layer and substrate interface in ULCB steel. These factors played important roles in forming a compact protective rust layer.     

中性介质中Q420qD高强桥梁钢的腐蚀行为

通过中性盐雾腐蚀试验、电化学测试等手段研究了Q420qD超低碳贝氏体高强桥梁钢和其对比材料F500L-Z普钢在中性介质中的腐蚀行为.结果表明:Q420qD超低碳贝氏体高强桥梁钢的耐腐蚀性优于F500L-Z普钢;其电化学阻抗值随金属材料浸泡时间的延长而增大,说明随着浸泡时间的延长,金属材料表面锈层不断加厚,逐渐增加了阻挡电解液对金属材料的侵蚀及金属材料表面金属原子失去电子向溶液中迁移的过程.     

碳钢和耐候钢在北京城市大气环境中初期腐蚀行为

对碳钢和耐候钢在北京城市大气中的初期腐蚀行为进行了研究．主要采用金相、扫描电镜、X-射线衍射方法分析和探讨了初期腐蚀层形貌、腐蚀产物和合金元素的分布．结果表明：在腐蚀初期，耐候钢表面生成的锈层较碳钢致密，裂纹和孔洞相对较少；25d后碳钢和耐候钢局部都出现了分层现象。腐蚀产物没有区别，差别主要是锈层中合金元素的作用．耐候钢锈层中有Cu、Cr合金元素的析出，聚集在裂纹处可抵御大气中水气及其有害离子的侵入，防止基体金属进一步腐蚀．     

电化学方法研究锈层覆盖下碳钢的腐蚀规律

分别采用失重法与电化学方法(包括极化曲线、线性极化法和电化学阻抗技术)研究了碳钢在海水中浸泡48周的腐蚀规律。结果发现,短期浸泡在海水中的碳钢,表面生成的腐蚀产物薄且疏松,长期浸泡后,锈层逐渐分为两层:外锈层薄且疏松,内锈层厚且致密。短期浸泡,失重法与电化学方法得到的腐蚀规律一致,腐蚀速度逐渐减小并且数值相近,此时电化学方法可以用来准确的估算碳钢的腐蚀速度。长期浸泡,电化学方法测定的腐蚀速度转为逐渐增大,偏离了失重结果,并且锈层越厚偏差越大,此时电化学方法会过高估算腐蚀速度。     

海水飞溅区Ni-Cu-P钢的锈层和耐点蚀性能研究

在海水飞溅区对实验室冶炼的Ni-Cu-P钢、含Cu低合金钢和碳钢进行660 d的挂片实验,评价Ni-Cu-P钢的耐蚀性能;采用Fourier变换红外(FTIR)光谱、电感耦合等离子体原子发射光谱(ICP-AES)、电子探针(EPMA)、SEM和EDAX等技术,分析3种钢表面的锈层特征.结果表明,Ni-Cu-P钢表现出比...     

Rust formation and corrosion performance of Si- and Al-bearing ultrafine grained weathering steel

A high Si, Al type ultrafine-grained (UFG) weathering steel was produced by the multi-pass warm rolling method, and its corrosion resistance was estimated by a cyclic wet/dry corrosion test using chloride ions. The Si- and Al-bearing UFG steel exhibited excellent corrosion resistance in comparison with Si–Mn carbon steel (SM).

EPMA and TEM analyses showed that Si and Al mainly exist in nano-scale iron complex oxides in the inner rust layer formed on the developed steel. The Al K X-ray spectrum of Al₂O₃ and metallic Al had different peak positions due to chemical shifts, and that of the test sample was the same as that of Al₂O₃ in the EPMA analysis. This result suggested that Al was present in the complex oxides as Al³⁺. In the same way, Si was identified as an intermediate state such as Si²⁺ in the complex oxides of the inner rust.

EIS (electrochemical impedance spectroscopy) measurement of the corrosion test samples revealed that the rust resistance (R_rust) and corrosion reaction resistance (R_t) of the developed steel were much larger than those of SM. It was found that nano-scale complex iron oxides formed in the lower layer of iron rust in the developed steel, resulting in increased R_rust and R_t, and finally suppressing corrosion.     

低碳贝氏体钢在青岛曝晒一年的锈层力学性能和抗热震性能研究

研究了低碳贝氏体钢在青岛曝晒一年后表面锈层的相组成、形貌、力学性能以及抗热震性能.结果表明:锈层由α-FeOOH、β-FeOOH、γ-FeOOH、Fe3O4以及非晶相组成;锈层的表面和截面形貌显示锈层较为致密,合金元素Cr和Cu在锈层中接近钢基体处有明显的富集现象;锈层的弹性模量和硬度随距锈层/钢基体界面的距离增大而降低;锈层/钢基体的结合强度和抗热震能力均高于锈层本身.     

耐候钢及其腐蚀产物的研究概况

介绍了耐候钢的发展、国内外使用及研究状况，概述了合金元素对耐候钢耐大气腐蚀性能的影响及其作用机制的研究进展，并对腐蚀产物的组成、锈层形成及其演变的电化学过程方面的研究进行了介绍，对今后耐候钢的研究与发展前景提出了展望。     

显微组织对低碳钢耐蚀性的影响

用不同热处理工艺得到铁素体+珠光体与马氏体两种不同组织的低碳钢,通过周浸试验和扫描电镜(SEM)、电化学和X射线衍射（XRD）等手段分析两者的耐蚀性能差异表明,在周浸试验条件下,组织均匀的马氏体钢的耐蚀性明显优于由铁素体和珠光体组成的复相钢;马氏体组织的自腐蚀电位较高,阳极腐蚀电流密度较小,形成的锈层更加致密,且主要由性质稳定的α-FeOOH构成。     

模拟工业大气条件下高锰耐候钢的腐蚀行为

应用电化学阻抗谱研究了在模拟工业大气的腐蚀溶液中Mn对耐候钢耐腐蚀性能的影响,并通过锈层电子探针面扫描验证了实验结果。电化学阻抗谱结果显示,在腐蚀初期高锰耐候钢表现出较强的点蚀反应特征,腐蚀后期则显示和比对钢相同的耐腐蚀能力。在模拟工业大气腐蚀条件下,Mn在耐候钢的内锈层中没有产生富集,Cr 和Cu在内锈层和钢基体界面中形成了富集带,这是保护性锈层生成的主要原因。     

Influence of carbon content and microstructure on corrosion behaviour of low alloy steels in a Cl containing environment

Corrosion behaviour of low alloy steels (A and B) with different carbon content was studied by a salt fog test and an outdoor test. A commercial weathering steel 09CuPCrNi was used for comparison. The corrosion resistance of steels A and B with homogeneous microstructures was better than that of the commercial weathering steel 09CuPCrNi in the salt fog test. Steel A with an ultra-low-carbon content had far less weathering resistance than the other steels in the outdoor test. Selective corrosion of large pearlite produces stress in initial corrosion product films. Uniform corrosion product films with few cracks tend to form on homogeneous microstructures such as ferrite and bainite, and this is advantageous for the formation of a compact rust layer in the initial stage of atmospheric corrosion. However, uniform microstructures will result in over even interfaces between rust layers and bases, which will lead to frequent peeling of rust layers from bases because stress is induced by large temperature fluctuations and wet-dry alternations. Protection of the rust layer on a low alloy steel is dependent on the rust density and the bonding performance of the rust-base rather than the proportion of the rust phase in the initial stage of atmospheric corrosion. These results indicate that homogenous microstructures, proper amounts of carbon content and fine carbon-rich phases that are produced by appropriate processes are beneficial for the corrosion resistance of steels.     

Corrosion behaviour of low-carbon bainitic steel under a constant elastic load

The corrosion behaviour of low-carbon bainitic weathering steel in an environment containing chlorine ions (Cl⁻) was studied by applying different constant elastic loads. The results showed that the applied elastic load reduces the resistance of the rust layer to Cl⁻ diffusion because of the porous structure as well as the enhanced anion selectivity in the rust: this leads to more severe corrosion of the steel compared with load-free conditions. The corrosion rate increased with increasing loads. Corrosion enhancement can be attributed to mechanical-chemical interactions at the steel surface.     

Cu,P,Cr 和 Ni 对低碳钢耐蚀性的影响简

选择Cu-P-Cr-Ni钢、Cu-P-Cr钢和Q235碳钢,在0.01 mol/L的NaHSO3溶液中进行周期浸润、阻抗谱和极化曲线实验,研究了Cu-P-Cr-Ni系合金钢相比Q235碳钢在模拟工业大气(SO2)环境下的耐腐蚀性能;利用SEM,EPMA面扫描和XRD分析腐蚀锈层的形貌、组成及Cu,Cr和Ni的元素分布情况。结果表明:Cu-P-Cr-Ni系钢的腐蚀诱发敏感性最低,其次为Cu-P-Cr钢,腐蚀速率分别为Q235碳钢的59.5%和52.8%;锈层分为内、外两层,致密的内锈层明显发生Cu的颗粒状、Cr的团聚状富集,外锈层主要有Cr的富集,Ni富集不明显。Cu和Cr等的富集可形成致密的内锈层,提高低碳钢的耐蚀性。     

海水中碳钢内锈层中的微生物及其对腐蚀的影响

通过在海水中现场挂样,检测了碳钢内锈层中的硫酸盐还原菌(SRB)、异养菌、铁细菌和硫 氧化菌的数量,用SEM观察了内锈层中腐蚀性细菌的形态和分布,并测定了内锈层中的FeS含量,研究了内锈层中微生物对碳钢海水腐蚀的影响及碳钢内锈层中的微生物及其腐蚀与大型生物、锈层、温度等的关系.结果表明：碳钢在海水中暴露1～120个月,内锈层中有大量的硫酸盐还原菌聚集,同时有不同数量的异养菌、铁细菌和中性硫氧化菌存在;内锈层中有高含量的FeS,并随暴露时间的延长而增加.在青岛、榆林海水中暴露1个月,碳钢的腐蚀已经受到微生物,尤其是SRB的显著影响.     

周期干湿浸条件下P265GH钢和Q235钢的大气腐蚀行为简

以NaCl+NaHSO3为腐蚀介质,通过浸渍干湿复合循环实验及腐蚀失重分析,并利用SEM,XRD和FTIR技术,研究了Q235碳钢和P265GH低合金钢的大气腐蚀行为。结果表明,两种钢的腐蚀遵从相同的动力学规律,腐蚀产物中均存在大量致密的α-FeOOH和非晶态δ-FeOOH,锈层具有很好的保护性,使得腐蚀速率降低。实验开始阶段两种钢的腐蚀量基本相同,但随着腐蚀的进行两者差距增大,P265GH低合金钢较Q235碳钢的失重小、锈层致密、耐腐蚀性好。     

真空油淬马氏体不锈钢表面白亮层的形成原因

马氏体不锈钢螺母的表面在空气环境中易出现棕黄色锈迹,利用光学显微镜、扫描电镜和化学元素检测等方法对马氏体不锈钢表面锈蚀进行分析。结果表明,马氏体不锈钢在真空固溶+油液淬火后表面形成一层均匀的白亮层组织,白亮层组织耐蚀性较正常的马氏体组织差,白亮层组织在空气中易锈蚀,锈蚀通常不穿透白亮层。通过碳含量测定及机理分析,认为白亮层产生的必要条件为真空加热、油液冷却。真空加热引起不锈钢表层合金元素Cr贫化、冷却时油液中的碳渗入导致表层增碳,导致淬火时不锈钢表层未发生马氏体转变,形成耐蚀性较差的白亮层组织。     

渗Al碳钢在高温精制环烷酸介质中的腐蚀行为

研究了固体渗Al碳钢在高温精制环烷酸中的腐蚀行为 ，并评价了渗Al层对碳钢抗环烷酸腐蚀性能的影响.结果表明：腐蚀初期，渗Al碳钢显示出 较好的抗蚀性能；但延长腐蚀时间，其抗蚀性能显著恶化，渗Al层以台阶方式逐层剥落.渗 Al碳钢表面氧化膜及Fe-Al合金层在精制环烷酸介质中的不稳定性是导致涂层抗蚀性能恶化 的主要原因.     

晶粒尺寸对普碳钢耐工业环境下大气腐蚀性能的影响

用不同轧制及热处理工艺制备了化学成分相同而晶粒尺寸不同的3种普碳钢试样。采周浸、锈层横截面微观分析、交流阻抗测试等手段对晶粒尺寸与普碳钢耐工业环境下大气腐蚀性能之间的规律进行了研究,同时测定了不同晶粒尺寸的普碳钢在10％硫酸溶液中的极化曲线。结果表明,普碳钢晶粒尺寸从50um减小到4um,周浸加速腐蚀试验后锈层中裂纹和空洞的数量也相应减少,耐蚀性能提高;但极化曲线试验表明,晶粒细化可加速普碳钢在10％H2SO4溶液中的腐蚀速度。分析了晶粒尺寸对晶界局部阳极腐蚀电流密度的影响,对其影响耐蚀性的机理进行了讨论。