海底尾水排放用X65MO超厚壁螺旋埋弧焊管的开发

为开发适用于尾水排放并满足海底运行条件的螺旋埋弧焊管，通过化学分析、显微组织分析和力学性能试验等方法，开发出一种低C及Mn-Cr-Mo-Nb系合金体系、多边形铁素体+粒状贝氏体+少量珠光体组织特征的X65MO材质、25.4 mm超厚壁热轧卷板。同时，通过径厚比、板宽、成型角对成型质量的影响规律和焊接线能量对焊缝质量的影响规律进行分析研究，确定出小径厚比、超厚壁Φ1 219 mm×25.4 mm钢管的成型参数和焊接参数，获得了低残余应力和高焊接质量的钢管，并且对试制的螺旋埋弧焊管的理化性能进行了检测。结果显示，钢管母材屈服强度为475～560 MPa，抗拉强度为570～635 MPa，焊缝抗拉强度为590～690 MPa；-10 ℃下的母材、焊缝和热影响区夏比冲击功平均值分别达到427 J、207 J和215 J，0 ℃下DWTT剪切面积平均值为98%；母材、焊缝和热影响区硬度最大值为241HV10。研究表明，试制的海底尾水排放用X65MO钢级Φ1 219 mm×25.4 mm超厚壁螺旋埋弧焊管具有良好的力学性能，可满足API SPEC 5L（46版）标准和工程技术条件要求。

Development of X65MO Ultra Thick Wall SAWH Pipe for Subsea Tailwater Discharge

In order to develop SAWH pipe suitable for tailwater discharge and meeting the seabed operating conditions, through chemical analysis, microstructure analysis and mechanical property test, a X65MO 25.4 mm ultra thick wall hot rolled coil with low C and Mn Cr Mo Nb alloy system, polygonal ferrite+granular bainite+a small amount of pearlite structure characteristics was developed. Through the analysis and research on the influence of diameter thickness ratio, plate width and forming angle on the forming quality and the influence of welding line energy on the weld quality, the forming parameters and welding parameters of small diameter thickness ratio and ultra thick wall steel pipe Φ1 219 mm×25.4 mm are determined, and the steel pipes with low residual stress and high welding quality were obtained, and the physical and chemical properties of the trial produced SAWH pipes are tested. The results show that the yield strength of base metal was 475～560 MPa, the tensile strength was 570～635 MPa, and the tensile strength of weld seam is 590 ～ 690 MPa. The average Charpy impact energy of base metal, weld seam and HAZ at - 10 ℃ reached 427 J, 207 J and 215 J respectively. The average DWTT shear area at 0 ℃was 98%, and the maximum hardness of base metal, weld seam and HAZ was 241HV10. The research shows that the trial produced X65MO Φ1 219 mm×25.4 mm ultra thick wall SAWH pipes for subsea tailwater discharge have good mechanical properties, which can meet the requirements of API SPEC 5L (46th edition) standard and engineering technical conditions.