中文摘要：

在管线钢中添加1％～5％（质量分数，下同）Cr可提高其抗CO2腐蚀能力，本工作重点研究了Cr含量对低Cr管线钢组织、力学性能、耐蚀性能及焊接性能的影响。结果表明：3％～5％Cr元素的添加可使钢的组织由铁素体加少量珠光体变为以贝氏体为主。1％以上Cr的加入即可提高钢的硬度、强度，同时保持良好的韧性。由于富Cr保护性腐蚀产物膜的形成，3％～5％Cr的添加可显著降低CO2全面腐蚀速率，并抑制局部腐蚀的发生。含1％～5％Cr的合金钢焊接接头具有较好的综合力学性能，但5％Cr钢焊接接头热影响区硬度偏高。

英文摘要：

1%-5% （mass fraction） Cr addition to pipeline steels can enhance their CO2 corrosion resistance. The effects of Cr content on the microstructure, mechanical properties, corrosion and welding characteristics were investigated for the low Cr pipeline steels. The results showed that 3%-5% Cr addition changed the microstructure of the steels from ferrite and pearlite into bainite. By adding more than 1% Cr, the hardness and strength of the steels were obviously improved combined with good toughness. With Cr content increasing to 3%-5%, CO2 general corrosion rate of the steels was reduced and localized corrosion was inhibited because of the protective corrosion scale with Cr element enrichment. Good mechanical properties could also achieve on the weld joints of the Cr containing steels. However, the hardness of heat-affected zone （HAZ） increased too much when Cr content reaching 5 %.