Microstructure, Wear Resistance and Corrosion Performance of Inconel 625 Layer Fabricated by Laser/Ultra-High Frequency (UHF) Induction Hybrid Deposition

Abstract

In order to avoid microstructure degradation caused by low frequency induction heat in laser-induction hybrid deposition, this paper proposes a laser/ultra-high frequency (UHF) induction hybrid deposition method. Microstructure observation is carried out to reveal the effect of UHF induction heat on the microstructure of the deposited layer. Results indicate that the laser-UHF induction hybrid deposited layer, under a current density of 1.14 × 108 A/m2, exhibits a finer microstructure and fewer Laves phases than that of the laser deposited layer. As the current density increases from 1.01 × 108 A/m2 to 1.14 × 108 A/m2, the microstructure of the laser-UHF induction hybrid deposited layer is significantly refined; however, as the current density further increases, the microstructure is only slightly further refined, since the enhanced thermal effect, along with the increasing current density, may help grain growth. Wear test demonstrates that the laser-UHF induction hybrid deposited layer obtained with a current density of 1.40 × 108 A/m2 has the lowest average friction coefficient of 0.375 and the lowest wear rate of 15.53 × 10−5 mm3/N·m, indicating a better wear resistance. Corrosion resistance is also evaluated by electrochemical corrosion test. Results indicate that the addition of UHF induction heat improves the corrosion resistance of the deposited layer. Owing to the high ohm resistance of the passive film, the deposited layer fabricated with a current density of 1.01 × 108 A/m2 exhibits the best corrosion resistance. Based on the analysis of wear and corrosion performance, the current density of 1.40 × 108 A/m2 is an optimal parameter for a laser-UHF induction hybrid deposited Inconel 625 layer.