机械复合管管端的耐蚀性

Corrosion Resistance of Mechanical Composite Pipe End

对油气管道用316L/X65双金属机械复合管管端进行了微观组织观察、化学成分分析及耐晶间腐蚀、点腐蚀性能评价。结果表明:复合管管端堆焊层分为内外两层,显微组织为柱状树枝状奥氏体组织,外层相比内层晶粒更细小,且外层堆焊层具有良好的耐蚀性;复合管管端的晶间腐蚀性能符合工程应用要求,耐点蚀性能由弱到强依次为316L-Inconel625、316L衬管、Inconel625堆焊层,温度升高会显著降低管端的耐点蚀性能,因电偶作用316L衬管与Inconel625堆焊层连接处的316L更易发生腐蚀。

The microstructure observation,chemical composition analysis and evaluation of intergranular corrosion resistance and pitting corrosion resistance of 316L/X65 bimetal mechanical composite pipe end used for oil and gas pipeline were carried out.The results showed that the cladding layer at the end was divided into two layers,the microstructure was columnar dendritic austenite,the grain of the outer layer was smaller than that of the inner layer,and the outer layer had good corrosion resistance.The intergranular corrosion resistance of the pipe end of the composite tube met the engineering application requirements.The pitting resistance from weak to strong can be ranked as 316L Inconel625,316L liner tube and Inconel625 surfacing layer.The pitting resistance of the pipe end would be significantly reduced when the temperature rised.The 316L at the joint of 316L liner and Inconel625 surfacing layer were more susceptible to corrosion due to the galvanic effect.