Liquid film migration in laser welded joint of Inconel 617
- PDF / 435,331 Bytes
- 8 Pages / 584.957 x 782.986 pts Page_size
- 15 Downloads / 202 Views
ie Yang Department of Welding Technology, Shanghai Turbine Works Company, Shanghai 200240, People’s Republic of China
Xia Liu Shanghai Turbine Plant of Shanghai Electric Power Generation Equipment Co. Ltd., Shanghai 200240, People’s Republic of China
Zhuguo Lia) Shanghai Key Laboratory of Materials Laser Processing and Modification, School of Materials Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240, People’s Republic of China (Received 10 March 2015; accepted 23 June 2015)
Liquid film migration (LFM) in the fiber laser welded Inconel 617 joint was investigated. The results show that the LFM occurs in HAZ of the laser welded Inconel 617 joint. The element of Mo in the migrated region is slightly richer than that in the adjacent matrix. The diffusional coherency strain due to the lattice mismatch between the element of Mo and the matrix atom is the dominant factor contributing to the occurrence of LFM in HAZ of laser welded Inconel 617. The migration of the liquid film is promoted by the thin initial liquid film and the slow cooling rate in large heat input. LFM tends to occur on the grain boundary (GB) with the fine particles and the GB-resolidified particles are formed on the GB with the large particles. Liquation cracking is reduced in the welds with the high heat input and in the solution treatment condition by LFM (1100 °C/1 h).
Contributing Editor: Jürgen Eckert a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2015.205
In 1979, Yoon and Huppmann4 have firstly discovered that the LFM occurs during the liquid phase interspersing of tungsten with the liquid nickel. The liquid film which initially separated the tungsten grains migrates into the dissolving grain, and the expanding grain grows by the formation of the W–Ni solid solution. This phenomenon was called LFM. Some studies on LFM in HAZ during the welding process have been reported by several researchers. Idowu et al.5 and Osoba and Ojo6 have briefly reported that the liquation cracking is reduced by LFM in laser welding of Inconel 718plus and Haynes 282. Ojo et al.7 have revealed that the liquid film caused by the constitutional liquation of the c9 particles is observed to migrate in HAZ of cast Inconel 738LC superalloy, however, liquation cracking is not prevented effectively by LFM. Acoff and Thompson8 have studied LFM in HAZ of Inconel 718 performed in the Geeble. The liquid film is produced by the constitutional liquation of the Nb-rich carbides. The concentration of the element Nb behind the migrated liquid film is shown to be slightly greater than the Nb concentration in the matrix. The Nb concentration in the area swept out by LFM decreases as the peak temperature increases. Nakkalil et al.9 have shown that the solute supersaturation of the liquid film is relieved by LFM during the electron beam welding of Incoloy 903.
2340
Ó Materials Research Society 2015
I. INTRODUCTION
Solid solution strengthened Ni-base superalloy Inconel 617 (UNS N06617) contains the high solid solution element (Mo, Cr, a
Data Loading...
