Abstract: This article mainly introduces the process flow,  process difficulties,  and innovative points of hot-rolled direct production of large-diameter medium thick wall P22 seamless steel tubes with a diameter of over Φ 900mm.  This research and development has the advantages of short process flow,  low production cost,  high yield,  The steel pipe has precise dimensions, good surface quality, and excellent performance. Base-d on the P22 seamless steel pipe produced by Φ820mm precision inclined rolling mill ,combined with the  requirement of grade 12Cr2MoG in GB/T 5310-2023 ,,the relevant indicators of P22 seamless steel pipes were analyzed through surface quality inspection, physical and chemical inspection and other methods.After testing,  the  produced P22 seamless steel pipe  had  properties as outer diameter deviation of -0.5mm-+6.2mm, ovality  of 0.58%,  wall thickness deviation of  -8.7%-+10.3%,  uneven wall thickness of 13.42%,  tensile strength of  513 MPa, ,511 MPa,  yield strength of  318, MPa, 311 MPa, elongation of  34.0%,33.0%, eaverage impact energy of 257J,242 J at room temperature ,  average hardness of 153/152 HBW,  microstructure of ferrite+bainite+a small amount of pearlite,  grain size of 6.0-7.0,  and ductile brittle transition temperature below -40 ℃; The results indicate that the chemical composition and various properties of large diameter medium thick walled P22 seamless steel pipes produced by the Φ 820 mm precision skew rolling mill meet the requirements of ASTM A 335/A 335M-24b and other standards.

Key words: P22 Seamless Steel Pipe, Large Diameter Over 900mm, Medium Thick Wall, Precision Oblique Rolling

摘要： 主要介绍热轧直接生产直径Φ900mm以上大口径中厚壁P22无缝钢管的工艺流程和工艺难点、创新点，该研发具有工艺流程短，生产成本低，成材率高，钢管尺寸精确、表面质量良好和性能优异等优点。基于 Φ820mm精密斜轧机组所生产的P22无缝钢管，结合GB/T 5310—2023中对牌号12Cr2MoG的要求，通过表面质量检验、理化检验等手段对P22无缝钢管的相关指标进行分析。 经检测得到生产的P22无缝钢管，外径偏差为-0.5~+6.2mm，椭圆度为0.58%，壁厚偏差为-8.7%~+10.3%，壁厚不均为13.42%，抗拉强度为513、511 MPa，屈服强度为318、311 MPa，伸长率为34.0%、33.0 %，室温冲击功均值为257、242J，硬度均值为153、152HBW，显微组织为铁素体+贝氏体+少量珠光体，晶粒度为6.0~7.0级，韧脆转变温度在-40℃以下；结果表明，基于Φ820 mm 精密斜轧机组所生产的大口径中厚壁P22无缝钢管的化学成分以及各项性能均满足ASTM A 335/A 335M—24b 等标准要求。

关键词: P22无缝钢管, Φ900mm以上大口径, 中厚壁, 精密斜轧