بهينه‌سازي پارامترهاي توليد آلياژ اينكونل 718 به روش لايه‌نشاني فلزي توسط ليزر

Direct Energy Deposition (DED), as one of the additive manufacturing approaches, has extensive applications in the fabrication an‎d restoration of complex industrial parts. The parameters influencing this method play a crucial role in determining the geometric characteristics of the deposited layers. In this research, the effect of laser scanning speed an‎d applied power on the weld pool geometry in the laser cladding process was investigated. For this purpose, geometric parameters including weld width, height, contact angle, porosity percentage, penetration area, total weld area, an‎d dilution percentage were measured using the ImageJ image processing software.The results indicated that increasing the power from 700 to 1100 W at a constant speed resulted in an increase in width (up to 2188 µm) an‎d the penetration area (up to 507,743 µm²), as well as a decrease in the contact angle (down to 44°). It was also found that increasing the scanning speed from 550 to 700 mm/min reduced the height an‎d the penetration area, but increased porosity under specific conditions. The maximum porosity (1.9%) was observed at a power of 900 W an‎d a speed of 700 mm/min, while the minimum porosity (0.17%) was observed at a power of 700 W an‎d a speed of 700 mm/min. The dilution percentage increased from 26% to 36% with increasing power an‎d decreased with increasing scanning speed.The low-speed strategy (550 mm/min, 900 W) yielded high penetration with moderate porosity (0.9%), whereas the high-power strategy (1100 W, 700 mm/min) resulted in similar penetration but higher porosity (1.7%). Ultimately, this study demonstrated that selec‎ting optimal parameters depends on balancing efficiency, porosity control, an‎d desired coating morphology.Microscopic examinations also revealed that the morphology an‎d amount of the Laves phase are a function of the ratio of input heat to cooling rate during deposition. Accordingly, it was determined that the amount of Laves phase has a direct relationship with the input heat in the deposition process; such that the volume fraction of this phase fluctuated between 22% an‎d 48%. Therefore, in coatings produced with higher input heat, a larger volume of the Laves phase is formed. Furthermore, the hardness of the fabricated coatings depends on the process parameters an‎d the amount of Laves phase. In samples produced with a higher cooling rate, higher hardness was achieved compared to other coatings due to the finer structure an‎d reduced amount of Laves phase.Corrosion test results also showed that samples produced at higher speeds exhibited lower secondary breakdown potential an‎d weaker resistance to pitting corrosion due to higher porosity an‎d structural defects. In contrast, decreasing the scanning speed reduced porosity an‎d increased the breakdown potential, thereby improving corrosion resistance. Overall, the corrosion behavior of the samples was predominantly influenced by the scanning speed, while laser power played a lesser role in altering localized corrosion resistance within the investigated range.

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امين اله محمدي

بهزاد نيرومند , مسعود عطاپور