Q355耐候钢加速腐蚀锈层演变规律研究

Study on the Evolution Law of Rust Layer in Accelerated Corrosion Test for Q355 Weathering Steel

利用加速腐蚀试验,对Q345低合金钢和Q355耐候钢不同时间腐蚀后试样的锈层形貌及腐蚀产物进行对比分析,结果表明:两种试验钢的锈层均主要由α-Fe OOH、γ-Fe OOH和Fe2O3组成,随着腐蚀时间延长,α-Fe OOH、γ-Fe OOH含量逐渐增加,Fe2O3含量逐渐降低,锈层颜色呈现黑色→红色→黄棕色的变化规律。与低合金钢相比,耐候钢锈层中α-Fe OOH含量在不同时间腐蚀后均比低合金试验钢高,并较早由不连续块/片状逐渐长大发展成连续/致密的针状或片状物,孔洞少且较致密平整,附着力强,不易脱落。耐候钢的腐蚀率明显低于低合金钢,且在试验涉及的腐蚀时间内变化不大。

By using the accelerated corrosion test, the systematic contrastive analysis on the rust layer morphology and corrosion products in Q345 low- alloy steel and Q355 weathering steel specimens corroded for different time was carried out. The results showed that, the rust layer was mainly composed of α-Fe OOH, γ-Fe OOH and Fe2O3, and with the extending of corrosion time, the content of α-Fe OOH and γ-Fe OOH gradually increased, and the content of Fe2O3 gradually decreased. And thus, the color of rust layer appeared the change rule of black → red → yellowish-brown. Compared with the low-alloy steel（Q345）, the content of α-Fe OOH in rust layer of weathering steel（Q355） was higher than the content of low-alloy steel after corroding for different test time,and it comparatively early grow into a continuous and compact acicular or flake matters from original discontinuous flake matters,more compact and smooth, with less holes and strong adhesion. So, the rust layer is not easy to fall off. Therefore, the corrosion rate of weathering steel was significantly lower than that of low-alloy steel, and it has little change within the different corrosion cycles in the range of experiment.