Effects of welding parameters on microstructure and mechanical properties of underwater wet friction taper plug welded pipeline steel
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Microstructure and mechanical properties of underwater wet friction taper plug-welded API X52 pipeline steel with 6500–7500-rpm rotational speed at 30–45-kN axial force have been investigated, and the defect-free friction taper plug-welded joints were obtained. It was found that the microstructure in welded joint was remarkably inhomogeneous and very different from the X52 base metal. The weld region could be divided into forged zone (FZ), final frictional plane (FFP), shear deformation zone (SDZ), bonding zone (BZ), and heat-affected zone (HAZ). The HAZ has the coarsest grain and mainly consists of martensite and bainite, and the FZ and SDZ are mainly characterized by a mixture of martensite, bainite, and various shapes of ferrites. The BZ is represented by the banding pattern of fine equi-axed grain ferrites because of local decarbonization around frictional interface in wet welding condition. The axial force has a greater impact on microstructure of welded joint as compared with rotational speed. The hardness profiles measured on cross section of welded joints are severely non-uniform, ranging from 200 to 400 HV1, due to the inhomogeneity of microstructures. The impact absorbed energy of bonding interface sites in welds was considerably lower than that of base metal (about 20% of parent metal) because of the local obviously coarse grain, Widmanstätten ferrites, and banding ferrite defects. The principle of “close mode” friction welding is illustrated, and the microstructural characteristics and mechanical properties of welds can be predicted by judging the type of friction welding.
KeywordsFriction taper plug welding API X52 pipeline steel Welding parameters Microstructure Mechanical properties
The authors acknowledge the financial support from National Natural Science Foundation of China (51475327).
- 1.Thomas WM, Icholas ED, Jones SR et al (1993) Friction forming: International Patent, WO 93/04813[P]Google Scholar
- 3.Łabanowski J, Fydrych D, Rogalski G (2008) Underwater welding - a review. Adva Mater Sci 8(3):11–22Google Scholar
- 4.Meyer A (2003) Friction hydro pillar processing: bonding mechanism and properties. GKSS- Forschungszentrum Geesthacht GmbH, HamburgGoogle Scholar
- 11.Yin Y et al (2014) Welding process and microstructure of weld for friction hydro pillar welded DH36 high strength steel. Trans China Weld Inst 35(9):109–114Google Scholar
- 13.Hou X (2013) Research on the experiments and the microstructure properties of friction hydro pillar processing. Tianjin University, TianjinGoogle Scholar