低合金钢在高矿化度矿井水环境下的腐蚀行为

Corrosion Behavior of Low Alloy Steels in High-mineralized Mine Water

对27Si Mn,30Cr Mn Si,30Cr Mn Ti,40Cr低合金钢以及Q550等5种液压支架常用钢在高矿化度矿井水中的腐蚀性能进行了研究,并以自来水、Na Cl溶液作为对比腐蚀介质进行比较。通过理论计算、盐雾实验、浸泡实验以及电化学实验进行了一系列腐蚀性能测试,同时利用SEM,EDS和XRD等分析手段对成分和形貌进行了分析。结果表明:Cr和Si对低合金钢的耐蚀性有较大影响:在Cl-环境下,Si的作用较大,Cr次之;在O2(水、大气)环境下,Cr的作用较大,Si次之。因此,在矿井水环境下,30Cr Mn Ti和40Cr低合金钢具有较好的耐蚀性。低合金钢在矿井水下的腐蚀,不仅与合金元素有关,还与矿物离子形成的垢膜致密性有关。水垢一方面填充了铁锈腐蚀产物疏松多孔的结构,减缓了低合金钢的腐蚀速率;另一方面,垢下区域由于电解质溶液中氧浓度较低,又加快了腐蚀速率。在3种不同腐蚀介质中,低合金钢的腐蚀程度从大到小依次为:3.5%Na Cl溶液>高矿化度矿井水>自来水。

The corrosion behavior of low alloy steels, such as 27SiMn, 30CrMnSi, 30CrMnTi, 40Cr and Q550 was studied comparatively in high-mineralized coal mine water, tap water and Na Cl solution by means of immersion test, salt spray test and electrochemical methods as well as XRD and SEM with EDS. The results showed that elements Cr and Si can significantly affect the corrosion resistance of low alloy steels： in chloride containing media, Si exhibits stronger effect than Cr on the corrosion; whereas in the presence of oxygen（water and gas phase）, Cr exhibits stronger effect than Si. Therefore, 30 Cr Mn Ti and 40 Cr have better corrosion resistance in the coal mine water.The corrosion behavior of the low alloy steels in the coal mine water depend not only on the role of alloying elements but also on the compactness of the formed limescale induced by mineral ions.The limescale, on one hand, can fill the porous rust layer, which slows down the corrosion rate of the steel, however, on the other hand, due to the low concentration of oxygen at the zone below the limescale, where the corrosion of the steel can be accelerated. Finally the corrosivity of three corrosive media can be ranked as the order from severe to mild： 3.5% Na Cl solution, high mineralized mine water and tap water.