Microstructural study of weld fusion zone of TIG welded IN 738LC nickel-based superalloy

Ojo, O.A.; Richards, N.L.; Chaturvedi, M.C.

doi:10.1016/j.scriptamat.2004.06.013

Cited by 118 publications

(68 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The solubility of Zr and B in c and c¢ is extremely low, 31,32,35,36 and thus, the aforementioned elements segregate into the boundary (c/c¢) eutectic-residual liquid interface, thus, providing favorable conditions for the precipitation of phases rich in Zr like Ni 5 Zr or Ni 7 Zr 2 and phases rich in B like M 5 B 3 or M 3 B 2 borides. 31,32,35,36 On the basis of phase equilibrium 37 for the binary alloy Ni-Zr, it can be clearly stated that only one eutectic reaction occurs (which takes place at 1170°C), in which L fi c + Ni 5 Zr. This stands in clear contrast with our observations.…”

Section: Microstructure Constituents and Solidification Pathmentioning

confidence: 99%

The Influence of the Melt-Pouring Temperature and Inoculant Content on the Macro and Microstructure of the IN713C Ni-Based Superalloy

Matysiak

Zagórska

Bałkowiec

et al. 2015

JOM

View full text Add to dashboard Cite

The aim of this work was to determine the effect of melt-pouring temperature T m and inoculant (cobalt aluminate-CoAl 2 O 4 ) concentration in the prime coat of the shell mold on the macro-and microstructure of the IN713C superalloy. The results show that cobalt aluminate is an effective modifier of the IN713C superalloy, which causes refinement of the equiaxed grains (EX) and a reduction of the fraction and size of the columnar grains on the casting surface. Also, the melt-pouring temperature in the range of 1450-1520°C was found to influence the mean EX grain size. Based on the results of differential thermal analysis of the alloy and detailed microstructure characterization, a sequence of precipitations has been proposed that advances current understanding of processes that take place during alloy solidification and casting cooling.

show abstract

Section: Microstructure Constituents and Solidification Pathmentioning

confidence: 99%

The Influence of the Melt-Pouring Temperature and Inoculant Content on the Macro and Microstructure of the IN713C Ni-Based Superalloy

Matysiak

Zagórska

Bałkowiec

et al. 2015

JOM

View full text Add to dashboard Cite

show abstract

“…As such it plays important role on the hot tearing susceptibility of the IN738LC superalloy. Ojo et al (2004) reported that at high cooling rates, partition coefficient of Zr is around 0.13 in IN738LC. This segregation not only increases the volume fraction of eutectic but also its spreading along grain boundaries, as shown in Fig.…”

Section: Tablementioning

confidence: 99%

Hot tearing in polycrystalline Ni-based IN738LC superalloy: Influence of Zr content

Heydari

Fard

Bakhshi

et al. 2014

Journal of Materials Processing Technology

View full text Add to dashboard Cite

a b s t r a c tZirconium is always present in Ni base superalloys as it enhances their creep properties. In the present study, the influence of very small Zr additions, 100-400 ppm, i.e. 0.01-0.04 wt.%, on hot tearing of IN738LC superalloy is experimentally investigated using dedicated turbine blade castings. Although the Zr content remains very small, it has a strong effect on hot tearing tendency. Microstructure of hot tear in as-cast samples reveal that grain size and secondary dendrite arm spacing have no significant effect on hot tearing. On the other hand eutectic phase volume fraction and its dispersion or spreading along grain boundaries drastically affect the hot tearing propensity and strongly increase with increasing amounts of Zr. Hence grain coalescence becomes impossible at grain boundaries covered with eutectic phase films. With increasing Zr content, gain coalescence between two distinct grains with no interdendritic phase requires more undercooling. Coalescence is retarded and occurs deeper in the mush zone, i.e. at lower temperatures resulting in a higher sensitivity to hot tearing. Finally, it is shown that a reduction of Zr content to 0.02 wt.% is required to fully suppress hot tearing in polycrystalline IN738LC blades.

show abstract

“…However, γ' precipitation-strengthened alloys are very difficult to weld in a crack-free manner due to their inherent susceptibility to heat affected zone (HAZ) cracking during welding and during post-weld heat treatment [1,2,3]. Despite the difficulties regarding crack-free welding of superalloys, welding is the most essential joining and repair process for turbine parts [4].…”

Section: Introductionmentioning

confidence: 99%

“…Various combinations of these parameters can lead to different cracking mechanisms such as · solidification (hot) cracking · constitutional liquation cracking along grain boundaries · sub-solidus / ductility dip cracking and · strain age cracking during post weld HT, see [1,2,3] for details.…”

Section: Introductionmentioning

confidence: 99%

A Study of the Weldability of Gamma Prime Hardened Superalloys

Schnell

Hoebel

Samuleson

2011

AMR

View full text Add to dashboard Cite

Fusion repair processes such as gas tungsten arc welding (GTAW) and laser welding have been introduced for repairing turbine parts made from Ni-based superalloy materials. The weld-repair of turbine parts is well established, however, the inherent susceptibility of γ' hardened superalloys to weld cracking remains an issue and has resulted in repair limitations for highly loaded areas of turbine parts. This study presents a view of the weldability of superalloys taking both, the impact of the weld process and the weld filler selection into consideration. This comprises the interpretation of specific process parameters into physical parameters controlling the weldability and cracking sensitivity such as thermal gradient in the weld pool and solidification speed. Alloy specific parameters of the weld filler material, such as melting point and solidification interval are studied and set in correlation with the solidification parameters during welding.

show abstract

Microstructural study of weld fusion zone of TIG welded IN 738LC nickel-based superalloy

Cited by 118 publications

References 8 publications

The Influence of the Melt-Pouring Temperature and Inoculant Content on the Macro and Microstructure of the IN713C Ni-Based Superalloy

The Influence of the Melt-Pouring Temperature and Inoculant Content on the Macro and Microstructure of the IN713C Ni-Based Superalloy

Hot tearing in polycrystalline Ni-based IN738LC superalloy: Influence of Zr content

A Study of the Weldability of Gamma Prime Hardened Superalloys

Contact Info

Product

Resources

About