Analysis on low temperature toughness of self-shielded flux cored wire used for pipeline

Low temperature toughness of deposited metal made by three types self-shielded flux-cored wires used for X70 pipeline has been investigated,by analyzing macroscopic and SEM morphology of impact fracture,microstructure and statistics of inclusion.The results showed that low temperature toughness of deposited metal of three wires was significantly different.No.3 wire has highest toughness with an impact absorbing energy average value of 330 J at-40℃,while the toughness of No.1 wire is the lowest,whose impact absorbing energy average value is only 113 J at-30℃.Differences of inclusions and microstructure of deposited metal were the main reason for significantly different toughness.Uniform and fine equiaxed grains and small inclusions uniformly and dispersedly distributed in deposited metal are beneficial to improve the low temperature toughness.