Mg处理X70级抗酸性海底管线钢(X70MOS)成分设计及耐蚀性能研究

Composition Design and Corrosion Resistance of Mg Microallyed X70 Grade Acid Resistant Submarine Pipeline Steel(X70MOS)

利用OLI Analyzer Studio软件,模拟海底管线管内NACE A和管外3.5%NaCl腐蚀环境,计算合金元素添加量对X70海底管线钢腐蚀速率的影响规律。在保证X70海底管线钢力学性能前提下,设计成分并轧制含0.003%Mg和无Mg的X70MOS实验钢。运用电化学测试技术和NACE TM 0284-2016标准,研究和评估X70MOS实验钢和常规X70海底管线钢的耐蚀性能和抗HIC性能。结果表明,Mg处理钢在NACE A溶液中较无Mg处理钢、X70海底管线钢腐蚀速率分别降低14.3%和73.3%,在3.5%NaCl溶液中分别降低52.8%和80.4%。Mg处理钢HIC敏感性较无Mg处理钢、X70海底管线钢大大降低,满足NACE标准规定值。X70MOS钢研制中使用0.003%Mg处理不仅可以降低合金成本,而且具有提高耐蚀性和抗HIC性能作用。

The corrosion rate of X70 submarine pipeline steel with alloying element addition in the so called NACE A medium and 3.5%NaCl solution was calculated by means of OLI analyzer studio software in order to simulate the corrosion situation of inner side and outer side of the real pipeline in service.Under the premise of ensuring the mechanical properties of X70 submarine pipeline steel,experimental X70MOS steels without and with 0.003%Mg-addition were designed and rolled.Then their corrosion resistance and hydrogen induced cracking(HIC)susceptibility were studied via electrochemical techniques in accord with NACE TM 0284-2016 standard.The results showed that corrosion rate of X70MOS steel with Mg-addition was lower than both that without Mg-addition and X70 submarine pipeline steel by 14.3%and 73.3%respectively in NACE A solution,and decreased by 52.8%and 80.4%respectively in 3.5%NaCl solution.The HIC susceptibility of the Mg-alloyed experimental steel with finely dispersed inclusions was lower than that of X70MOS steel without Mg-addition and X70 submarine pipeline steel.The development of X70MOS steel with 0.003%Mg-addition can enhance the corrosion resistance of the designed steel.