Preheat of X80 pipeline steel

During the welding process of X80 pipeline steel, the microstructure and properties of the heat-affected zone will be greatly changed due to the heat of the welding process, especially the microstructure and properties of the coarse-grained heat-affected zone change the most. Using thermal simulation technology, engineering test method and microscopic analysis method were used to study the influence of preheating temperature on the charpy impact toughness of the coarse-grained heat affected zone of X80 pipeline steel, and the reasons were analyzed to determine the preheating of the pipeline under small line energy. Temperature. It is considered that welding under small line energy, preheating before welding is beneficial to the toughness of the coarse grain zone. When the field welding line energy is 10 kJ/cm, it is recommended that the preheating temperature before welding is 150 °C; Welding under energy, preheating before welding has no benefit to the toughness of the coarse grain zone. If the preheating temperature is too high, it will cause damage to the toughness of the coarse grain zone and should be limited.