低成本高韧性X70钢级板卷及螺旋埋弧焊管的研制

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The alloy design, microstructure and mechanical properties of X70 grade submerged - arc weld- ing helical （SAWH） pipe with lower or without expensive Mo alloy were researched. The excellent low temperature toughness welding materials and welding technology were also developed. The research results show that the low cost X70 grade steel pipe reached the requirements of technical conditions. The Bausch- inger effect value is only 8 MPa, steel pipe circumferential spring back is within 30 mm, the Charp impact energy for pipe body, welding seam and heat affected zone at -29 ℃ were better than the second west - east gas pipeline project technical conditions of grade X70 steel pipe, and the products were successfully applied in pipeline projects abroad.研究了X70钢级减少或不添加价格昂贵的Mo等合金的螺旋焊管的化学成分、组织及性能，以及优异低温韧性钢管的焊材、焊接工艺。结果表明，研制的低成本钢管达到技术条件的要求，其包辛格效应值较小，为8MPa；钢管周向弹复在30mm以内；-29℃的管体横向、焊缝及热影响区的夏比冲击功均优于西气东输二线技术条件X70钢级钢管的指标，并成功应用于国外管道工程。