Nb-Cr X80管线钢管焊接接头断裂韧性的研究

对低温环境下Nb—CrX80管线钢管及其焊接接头的断裂韧性进行了深入研究。研究发现．Nb—Cr X80管线钢母材的抗开裂性能要优于热影响区，纵焊缝介于二者之间。对于KOBELB52U φ3．2mm低氢焊条上向根焊＋HOBART X80 φ2．0mm自保护药芯焊丝半自动下向填充盖面焊环焊接头，焊缝NQ方向的抗开裂能力优于NP方向，但热影响区的性能却是NP方向优于NO方向；而对于KOBELB52U φ3．2mm低氢焊条上向根焊＋金桥JC-30φ2．0mm自保护药芯焊丝半自动下向填充盖面焊环焊接头，焊缝及HAZ试样，NQ方向CTOD平均值要高于NP方向．说明NO方向抗开裂能力更好。

Study on the Fracture Toughness of Welding Joint for Nb-Cr X80 Line Pipe

The Nb-Cr X80 line pipe and fracture toughness of its welding joint were studied at low temperature.It was found that for Nb-Cr X80 pipeline steel,the anti-cracking performance of the base metal is better than that of HAZ, while the cracking performance of longitudinal weld is between base metal and HAZ.For circumferential welding joint deposited by KOBE LB52Uφ3.2 mm upward(for root pass)+HOBART X80φ2.0 mm self shielded flux-cored wire downward(for fill,and cap passes),the anti-cracking performance of NQ direction is better than that of NP direction. However,for HAZ,the anti-cracking performance of NQ direction is worse than that of NP direction.In the case of welding joints deposited by KOBE LB52Uφ3.2 mm upward(for root pass)+JC-30φ2.0 mm self shielded flux-cored wire downward(for fill,and cap passes),for NQ direction,both the average value of CTOD of weld metal and HAZ are better than that of NP direction.This indicates anti-cracking performance in NQ direction is better.