高强耐候钢Q450NQR1腐蚀规律和机制

Corrosion Rules and Mechanism of High Strength Steel of Q450NQR1

通过采用周浸腐蚀试验方法研究了Q450NQR1高强耐侯钢和Q345钢在浓度为0.01mol/L的亚硫酸氢钠溶液中,经过6,24,48,72和96h周浸腐蚀试验后的耐腐蚀性能,并测试了不同周浸腐蚀时间后试样的腐蚀电位和腐蚀电流密度。研究发现,Q450NQR1钢腐蚀速率随试验时间延长而下降,其表面的锈蚀产物膜在周浸腐蚀试验48h后基本达到稳定。Q450NQR1钢在浸泡各个周期内相对Q345钢均有更好的耐腐蚀性。电化学极化实验证实Q450NQR1钢的腐蚀电流48h后趋于稳定,而Q345B48h后腐蚀电流密度略有增大,这与周浸腐蚀试验结果是一致的。微观腐蚀形貌及EDS分析认为这是由于Q450NQR1钢中添加的Cu和Cr元素参与了腐蚀成膜,并促使腐蚀产物膜整齐致密。XRD分析结果表明,Q450NQR1钢随时间延长,腐蚀产物中的α-FeOOH含量不断增加,在48h后含量基本稳定,大量α-FeOOH促使了锈层更加致密稳定,从而提高了Q450NQR1试样的耐腐蚀能力。

According to the requirement of Ministry of Railways of China, the strength of steel plate used for railway truck is improved to 450 MPa. Many Chinese steel companies developed their own Q450NQR1, which is a kind of high strength weathering steel containing Cu, Cr, Ni and other alloying elements. For most products, the mechanical properties are excellent; however their atmospheric corrosion resistance is not that good in practical applications, because specialist on corrosion has seldom participated in the developing process of Q450NQR1. The accelerated corrosion properties of high strength weathering steel Q450NQR1 are studied and compared with mild carbon steel Q345B by means of the periodical immersion cyclic corrosion test. The corrosion potential and corrosion current density are analyzed by electrochemical technology. The results show that under the testing conditions, the weight losses and average corrosion rates for steel Q450NQR1 are remarkably lower than that for steel Q345B. The corrosion product formed on steel Q450NQR1 is more stable than that on steel Q345B, and it reached at stable condition after 48 hours. The same conclusions are drawn by the electrochemical polarization test and open potential measured. The EDS and XRD results suggest that Cu and Cr are able to improve the stability of corrosion product formed on steel Q450NQR1, and with the in-creasing contents of α-FeOOH, which provides a better and stable protection from further corrosion of the substrate, the corrosion resistance of steel Q450NQR1 is improved.