Study on Microstructure and Fracture Behavior of X100 Pipeline Steel Welded Joints

Effects of welding heat input on the microstructure, Vickers microhardness and CTOD of the CO₂ shielded arc welded joints of X100 pipeline steel were investigated. The results showed that compared with those of 15 kJ/cm, the Vickers microhardness and CTOD in the coarse grain area in the heat affected zone of 30 kJ/cm were lower, that's because the content of the bainites decreased under the welding heat input of 30 kJ/cm.