Study On The Corrosion Behavior Of Carbon Steel In Ku'erle Soil

In this paper , the 1~7 days initial corrosion behavior and the 7~30 days short-time corrosion behavior of X70 steel and Q235 steel in 25,30,35℃, 1.04%,2%,3% moisture content Xinjiang Ku'erle soil were studied by indoor corrosion simulation test, SEM, EDS , XRD, and the result of the macro-morphology, weight loss, corrosion area, corrosion depth, elemental and chemical composition of corrosion product. By combining electrochemical kinetics, the corrosion process, the law of corrosion, and corrosion mechanism were discussed. On the basis of them, the selection of localized corrosion evaluation indicators was preliminarily discussed.The results showed the 1~7 days initial corrosion state of two kinds of carbon steel in 35℃, 1.04%,2%,3% moisture content Xinjiang Ku'erle soil was typical local corrosion that began from small holes and spots , and then developed widely and deeply , and gradually developed into patches of corrosion pits. Comparing with the corrosion depth, the corrosion area expanded more rapidly. Different moisture content led to different corrosion state and corrosion rate. EDS analysis showed that in the initial period , the corrosion products of two kinds of carbon steel in original soil were the same But there were differences in specific initial corrosion behavior of them. Most of all, the corrosion horizontal expansion of Q235 steel in original soil was faster than that of X70 steel, only 7 days Q235 steel developing into non-uniform general corrosion.The 7~30 days short-time corrosion state of two kinds of carbon steel in 20,30,35℃, 1.04%,2%,3% moisture content Xinjiang Ku'erle soil was mostly typical local corrosion. Temperature and moisture content were both the important factors which affected the short-term corrosion behavior of carbon steel in Xinjiang Ku'erle soil. From the point of view that temperature influenced on corrosion behavior, corrosion behaviors in the original soil under various temperature were similar. Temperature had a prominent influence on the corrosion expansion only in the horizontal. The rise of temperature accelerated corrosion development. From the point of view that moisture content influenced on corrosion behavior, corrosion behaviors in 35℃under various moisture content were different. The corrosion behaviors in the original soil and 3% moisture content were two different ones. The corrosion behavior in 2% moisture content possessed that of in the original soil and 3% moisture content. Moisture content had a prominent influence on the corrosion expansion not only in the horizontal but also in the vertical. The increase of moisture content also accelerated the corrosion, and r-FeOOH was generated which had never been generated in original soil. There were also differences in specific initial corrosion behavior of two kinds of carbon steel. The differences of initial corrosion behavior and the short-time corrosion behavior between X70 steel and Q235 steel indicated that X70 steel's corrosion resistance was better than Q235 steel's.