Causes analysis on cracks in nickel-based single crystal superalloy fabricated by laser powder deposition additive manufacturing

Zhou, Zhipeng; Huang, Lan; Shang, Yijing; Li, Yunping; Jiang, Liang; Lei, Qian

doi:10.1016/j.matdes.2018.10.042

Cited by 136 publications

(27 citation statements)

References 31 publications

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“…Cracking seems to be inhibited using a pre-heating temperature of 450 • C (Figure 4B). Similar crack formation along the build direction in LMD-produced samples has been reported for other materials, such as IN718 (Zhou et al, 2018). In that case, cracking was observed at track overlapping regions.…”

Section: Processability In Lmdsupporting

confidence: 83%

Laser Metal Deposition of Ultra-Fine Duplex AlCrFe2Ni2-Based High-Entropy Alloy

et al. 2020

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A duplex, nano-scale Co-free high-entropy alloy (HEA) based on AlCrFe 2 Ni 2 was processed using laser material deposition (LMD). Process parameters in various beam diameter configurations, as well as deposition strategies, were used while the alloy microstructure was investigated in the as-built and heat-treated condition. Interlayer regions present a duplex microstructure composed of ultra-fine face-centered cubic (FCC)-platelets nucleated in a nano-scale structured body-centered cubic (BCC) phase. Rapid cooling during LMD induces the decomposition of the BCC phase into ordered and disordered nano-scaled structures. The hard and brittle BCC phase yields a high crack susceptibility during rapid cooling in the LMD process. A suitable processing strategy paired with a post-processing heat treatment was developed to solve this challenge. After heat treatment at 900 • C and 6 h annealing time with subsequent furnace cooling, the material presented a homogeneous duplex ultra-fine FCC/BCC microstructure and high bending strength (2310 MPa) compared to a heat-treated cast duplex-steel (1720 MPa) while maintaining excellent ductility (no failure at 20% bending strain).

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Section: Processability In Lmdsupporting

confidence: 83%

Laser Metal Deposition of Ultra-Fine Duplex AlCrFe2Ni2-Based High-Entropy Alloy

et al. 2020

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“…However, for the judgment of cracking mechanism of other cracks in Figure 5a, it is not sufficient to observe only the growth direction. Because of the complex solidification process of melting, remelting, partial remelting, cyclic annealing, and countless HAZ within the LFRed coating, it is difficult to identify whether the cracking behavior belongs to the liquation cracking or solidification cracking [38,39]. It can at least be determined that crack 1 in Figure 5a belongs to the liquation crack, as it exists in the original HAZ and is similar to an upward growth direction parallel to deposition.…”

Section: Liquation Crackingmentioning

confidence: 99%

Cracking, Microstructure and Tribological Properties of Laser Formed and Remelted K417G Ni-Based Superalloy

Liu

Wang

et al. 2019

Coatings

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The K417G Ni-based superalloy is widely used in aeroengine turbine blades for its excellent properties. However, the turbine blade root with fir tree geometry experiences early failure frequently, because of the wear problems occurring in the working process. Laser forming repairing (LFR) is a promising technique to repair these damaged blades. Unfortunately, the laser formed Ni-based superalloys with high content of (Al + Ti) have a high cracking sensitivity. In this paper, the crack characterization of the laser forming repaired (LFRed) K417G—the microstructure, microhardness, and tribological properties of the coating before and after laser remelting—is presented. The results show that the microstructure of as-deposited K417G consists of γ phase, γ′ precipitated phase, γ + γ′ eutectic, and carbide. Cracking mechanisms including solidification cracking, liquation cracking, and ductility dip cracking are proposed based on the composition of K417G and processing characteristics to explain the cracking behavior of the K417G superalloy during LFR. After laser remelting, the microstructure of the coating was refined, and the microhardness and tribological properties was improved. Laser remelting can decrease the size of the cracks in the LFRed K417G, but not the number of cracks. Therefore, laser remelting can be applied as an effective method for strengthening coatings and as an auxiliary method for controlling cracking.

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“…However, for the judgment of cracking mechanism of other cracks in Figure 5a, it is not sufficient to observe the growth direction only. Due to the complex solidification process of melting, remelting, partial remelting, cyclic annealing and countless HAZ within the LFRed coating, it is difficult to identify the cracking behavior belongs to the liquation cracking or solidification cracking [33,34]. At least it can be determined that crack 1 in Figure 5a belongs to the liquation crack, as it exists in the original HAZ and is similar to an upward growth direction parallel to deposition.…”

Section: Solidification Crackingmentioning

confidence: 99%

Cracking, Microstructure and Tribological Properties of Laser Formed and Remelted K417G Ni-Based Superalloy

Liu¹,

Yu²,

Wang³

et al. 2018

Preprint

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K417G Ni-based superalloy is widely used in aeroengine turbine blade for its excellent properties. However, the aeroengine rotor blade zigzag crown appears early failure frequently, which is because of the wear problems occurring in the working process. Laser forming repairing (LFR) is a promising technique to repair these damaged blades. Unfortunately, the laser formed Ni-based superalloys with high content of (Al + Ti) have a high cracking sensitivity. In this paper, the crack characterization of the LFRed K417G, the microstructure, microhardness and tribological properties of the coating before and after laser remelting are presented. The results show that the microstructure of as-deposited K417G consists of γ phase, γ′ precipitated phase, γ + γ′ eutectic and carbide. Cracking mechanisms including solidification cracking, liquation cracking and ductility dip cracking are proposed based on the composition of K417G and processing characteristics to explain the cracking behavior of the K417G superalloy during LFR. After laser remelting, the microstructure of the coating has been refined, and the microhardness and tribological properties has been improved. Laser remelting can decrease the size of the cracks in the LFRed K417G but not the number. Therefore, laser remelting can be applied as an effective method for strengthening coating and as an auxiliary method for controlling cracking.

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Causes analysis on cracks in nickel-based single crystal superalloy fabricated by laser powder deposition additive manufacturing

Cited by 136 publications

References 31 publications

Laser Metal Deposition of Ultra-Fine Duplex AlCrFe2Ni2-Based High-Entropy Alloy

Laser Metal Deposition of Ultra-Fine Duplex AlCrFe2Ni2-Based High-Entropy Alloy

Cracking, Microstructure and Tribological Properties of Laser Formed and Remelted K417G Ni-Based Superalloy

Cracking, Microstructure and Tribological Properties of Laser Formed and Remelted K417G Ni-Based Superalloy

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