Y. Tian

Erratum to: Microstructure Evolution and Rapid Solidification Behavior of Blended Nickel-Based Superalloy Powders Fabricated by Laser Powder Deposition

Laser powder deposition was performed on a substrate of Inconel 738 using blended powders of Mar M247 and Amdry DF3 with a ratio of 4:1 for repairing purposes. In the as-deposited condition, continuous secondary phases composed of γ-Ni3B eutectics and discrete (Cr, W)B borides were observed in inter-dendritic regions, and time-dependent nucleation simulation results confirmed that (Cr, W)B was the primary secondary phase formed during rapid solidification. Supersaturated solid solution of B was detected in the γ solid solution dendritic cores. The Kurz–Giovanola–Trivedi model was performed to predict the interfacial morphology and correlate the solidification front velocity (SFV) with dendrite tip radius. It was observed from high-resolution scanning electron microscopy that the dendrite tip radius of the upper region was in the range of 15 to 30 nm, which yielded a SFV of approx 30 cm/s. The continuous growth model for solute trapping behavior developed by Aziz and Kaplan was used to determine that the effective partition coefficient of B was approximately 0.025. Finally, the feasibility of the modeling results were rationalized with the Clyne–Kurz segregation simulation of B, where Clyne–Kurz prediction using a partition coefficient of 0.025 was in good agreement with the electron probe microanalysis results.

Laser Wire Deposition of Thick Ti-6Al-4V Buildups: Heat Transfer Model, Microstructure, and Mechanical Properties Evaluations

This paper investigates the effect of depositing thick laser wire Ti-6Al-4V samples on the developed microstructure and subsequent mechanical properties. First, a thermal model is proposed to get a better understanding on the typical thermal cycles that the material has undergone. It is followed by a discussion on the typical structural features that developed in the as-built condition and following three post deposition heat treatments. A stress relief cycle did not substantially affect the morphology of the developed α platelets. Annealing and HIP followed by aging favored the coarsening of the post-deposited microstructure. A strengthening in terms of hardness has been observed only after the stress relief heat treatment. Developed static tensile properties were globally below the wrought levels. Stress-relieved specimens developed the higher strengths, whereas the annealed or HIPed samples followed by aging were associated with a better elongation. Charpy impact properties were higher in the annealed or HIPed condition followed by aging when compared with the stress-relieved ones. No anisotropy in the impact toughness properties was observed. The annealed and aged samples and the HIPed and aged samples produced overall very similar results showing that HIP is not required for enhance materials properties of laser wire deposition applications.