低温管线K65热煨弯管用埋弧焊丝研制

Development of submerged arc welding wire for fabrication of hot bend low-temperature pipeline steel K65 pipe

设计了NiMoTiB体系实芯焊丝用于低温管线K65热煨弯管的埋弧焊接，并采用φ4.0 mm焊丝、双面四丝埋弧焊开展了壁厚30.8 mm直缝管试制，然后利用热煨弯制工艺制成弯管，并分别测试了直缝管和弯管的焊缝金属微观组织及力学性能.结果表明，焊态直缝管焊缝组织以针状铁素体为主，以及少量贝氏体及马氏体-奥氏体岛（M-A）；焊缝金属抗拉强度670 MPa，-40℃冲击吸收功为162 J.经过淬火＋回火处理的热煨弯管焊缝主要由块状铁素体和尺寸1-5 μm的退化珠光体组成；焊缝金属抗拉强度665 MPa，-40℃冲击吸收功84 J，能够满足低温管线钢K65的标准要求.

A NiMoTiB type solid wire was developed for submerged arc welding of hot bended K65 linepipe,and microstructure and mechanical property of the fabricated pipe with a wall thickness of 30.8 mm welded by two-sided four wire submerged arc welding were analyzed and tested.The results shows that the weld metal of as-welded pipe consists of acicular ferrite,a few bainite and M-A constituents,which has a tensile strength of 670 MPa and the impact absorbed energy is no less than 162 J at-40 ℃.Hot bending process changed the weld metal microstructure into a mix of blocky ferrite and pearlite,while possesses the tensile strength of 665 MPa and impact absorbed energy of no less than 84 J at-40 ℃.