超低碳微合金X100管线钢CO2焊焊接接头的组织和性能

 采用CO2焊接方法焊接X100管线钢，分析了不同焊接工艺下焊接接头组织和性能的变化特征。随着焊接热输入的增加，焊接接头的屈服强度和抗拉强度降低，焊缝和热影响区处的冲击吸收功呈现先增大后减小的变化趋势，而焊缝组织均以针状铁素体（AF）为主。焊接热输入为1.17 kJ/mm时，粗晶区的显微组织主要是贝氏体铁素体（BF），强韧匹配性最为优异；当热输入增加至1.91 kJ/mm时，粗晶区的组织除了BF外，还出现了粒状贝氏体（GB），强韧水平明显降低。综合考虑，可将1.17 kJ/mm作为X100管线钢CO2焊接时的最佳热输入。

Microstructure and Properties of CO2 Arc Weld Joints for Ultralow-Carbon Microalloyed X100 Pipeline Steel

CO2 arc welding technique was employed to weld X100 pipeline steel. The influence of welding procedure on the microstructure and properties of welding joints was analyzed. With the weld heat input increasing, the yield strength and tensile strength of welded joints decreased and the impact absorption energy of the weld and heat affected zone increased at first then decreased. However, the microstructure of all welds was mainly made up of acicular ferrite. The main microstructure in CGHAZ was bainitic ferrite which could bring excellent strength and toughness when the heat input was 1.17 kJ/mm. As the weld heat input was increased to 1.91 kJ/mm, Granular bainite and bainitic ferrite were formed, the strength and toughness decreased. Considering all these factors, 1.17 kJ/mm was recommended as the optimal heat input in the CO2 arc welding process of X100 pipeline steel.