显微组织对桥梁钢模拟海洋潮差区腐蚀行为的影响

对采用不同热处理工艺的桥梁钢在3.5%NaCl溶液中和人工海水中分别进行了极化曲线测量和周期浸润加速腐蚀试验,采用失重法和腐蚀产物分析研究了腐蚀演化规律。结果表明,经回火处理后,桥梁钢的组织由粒状贝氏体非平衡组织向回火索氏体平衡组织转变,晶粒细化、组织更为均匀,因此具有更好的耐腐蚀性能。经过640℃回火处理后的钢耐腐蚀性最佳。周期浸润腐蚀试验中的锈层能对钢基体起到一定的保护作用,但轧态粒状贝氏体组织钢外锈层中FeOOH的α/γ比较低、内锈层的α-Fe较高,锈层保护性较差。

Influence of Microstructure on Corrosion Behavior of Bridge Steels in Simulated Ocean Tide Zone

Bridge steels with different heat treatment processes were used for polarization curve measurement in 3.5% NaCl solution and alternate immersion accelerated corrosion testing in artificial seawater.The corrosion evolution of bridge steels was studied by weight-loss method and corrosion product analysis.The results showed that the microstructure of the bridge steels was changed from non-equilibrium granular bainite to equilibrium temper sorbite after drawing temper.Because of the grain refinement and uniformity of structure,the corrosion resistance of temper sorbite microstructure was better than that of granular bainite microstructure in simulated ocean tide zone.As carbide grains were dispersive and fine,the seawater corrosion resistance of the sample tempered at 640 ℃ was the best in simulated ocean tide zone.The rust layer formed through alternated immersion test provided protection for the substrate steels,but α/γ in the outer rust layer FeOOH of hot rolled sample with granular bainite microstructure was relatively low and the percentage of α-Fe in inner rust layer was relatively high,resulting in fairly poor protection capability of the rust layer.