X70级HFW焊管在线中频感应热处理工艺研究

X70 Grade HFW Pipe On-line Mid-frequency Induction Heat Treatment Process Research

为了探究X70级HFW焊管在线中频感应热处理工艺,通过采用不同的焊后在线正火热处理工艺方案进行了试验研究,比对了X70级HFW焊管热处理后组织与性能的变化情况。试验结果显示,中频感应加热正火温度和加热保温时间对焊接区的金相组织和性能有显著影响;910℃保温17 s、950℃不保温正火后,焊接区有硬质相组织,焊缝抗拉强度高,但塑性韧性低;980℃正火后,金相组织粗大,焊缝抗拉强度降低;950℃保温17 s正火后,金相组织为均匀细小的F+P,焊缝塑性韧性提高。试验结果表明,采用950℃正火,在此温度下适当的延长正火保温时间,能够获得良好的金相组织和综合力学性能。

In order to explore on-line mid-frequency induction heat treatment process of X70 HFW pipe, in this article, it conducted tests through adopting different online normalizing heat treatment process after welding, and compared the microstructure and properties change of X70 HFW pipe after heat treatment. The results showed that the normalizing temperature and heat preservation obviously affect the metallographic structure and properties of welding zone. After heat preservation for 17 s at 910℃or normalizing at 950 ℃without heat preservation, the hard phase microstructure appeared in welding area, the tensile strength of weld was high, and the plasticity and toughness were low. After normalizing at 980 ℃, the metallographic structure became coarse, and the tensile strength of weld decreased. After normalizing with heat preservation for 17 s at 950℃,the metallographic structure composed of even and fine F＋P, and the plasticity and toughness of weld increased. The test results indicated that normalizing at 950 ℃with suitably prolonged heat preservation duration will achieve good metallographic structure and comprehensive mechanical properties.