耐硫酸露点腐蚀用Q345NS超大管径螺旋埋弧焊管的开发

Development of Super Large Diameter Spiral Submerged Arc Welding Pipe of Q345NS for Sulfuric Acid Dew Point Corrosion Resistance

采用低C、低S,添加Cr、Cu、Sb等合金元素和洁净化冶炼、控轧控冷工艺生产的耐硫酸露点腐蚀用Q345NS热轧卷板,通过优化成型器结构和焊接工艺参数,选用耐酸性焊接材料,控制焊接热输入、钢管成型残余应力等措施,开发出了耐硫酸露点腐蚀用Q345NS超大管径螺旋埋弧焊管,并对其化学成分、显微组织、力学性能、耐酸性能进行了检测。结果表明,焊管管体屈服强度为374~398 MPa,抗拉强度为498~526 MPa,焊缝抗拉强度为510~531 MPa,管体、焊缝及热影响区夏比冲击试验韧脆转变温度分别达到-50℃、-30℃、-30℃;按照GB/T 28907—2012附录A规定进行均匀腐蚀全浸试验,在温度20℃、硫酸浓度20%、全浸24 h以及温度70℃、硫酸浓度50%、全浸24 h两种试验条件下,与Q235B材质相比,Q345NS螺旋钢管耐硫酸露点腐蚀性能具有明显的优势;该钢管表现出良好的力学性能和耐酸性能。

Sulfuric acid dew-point corrosion resistant Q345NS hot-rolled coil was obtained by using the low C,low S,adding the alloying elements such as Cr,Cu,Sb and through the clean smelting,the controlled rolling and controlled cooling process.By optimizing the shaper structure and welding process parameters,selecting the acid-resistant welding materials,controlling the welding heat input,and controlling the residual stress of steel pipe molding,the Q345NS super large diameter spiral submerged arc welded pipe for the dew point corrosion resistance was developed,and its chemical components,microstructure,mechanical properties and acid resistance were tested.The results show that the yield strength of the welded pipe body is 374~398 MPa,the tensile strength of the welded pipe body is 498~526 MPa,and the tensile strength of the weld is 510~531 MPa.The ductile and brittle transition temperatures of the Charpy impact test of the pipe body,the weld and the heat affected zone reached-50℃,-30℃,and-30℃respectively.According to the GB/T 28907—2012 appendix A,a uniform corrosion full immersion test is performed.The test conditions are at a temperature of 20℃,the sulfuric acid concentration is 20%,a full immersion for 24 h,and a temperature of 70℃,a sulfuric acid concentration of 50%,and a full immersion for 24 h.Compared with Q235B material,Q345NS spiral steel pipe has obvious advantages in resistance to sulfuric acid dew point corrosion;the steel pipe shows good mechanical properties and acid resistance.