PSI - Issue 54

Daniel F.O. Braga et al. / Procedia Structural Integrity 54 (2024) 626–630 / Structural Integrity Procedia 00 (2023) 000–000 Daniel F.O. Braga et al.

629

4

Fig. 2. Strain field evolution during tensile testing (Run Order #7)

3. Results and Discussion

The resulting Ultimate Tensile Strength (UTS) and elongation averages and standard deviations are plotted in Fig. 3. Small variation was found in UTS in between parameter sets and UTS standard deviation was also low, which indicates that the parameter window studied was not overly wide, which would result in unstable material processing. The UTS of all sets tested was within the reported valued for LMD Inconel 625 by Zafar et al. (2023), but lower than reported for wrough Inconel 625 by Nguejio et al. (2019). The average UTS was then used in analysis of variance (ANOVA), to determine the contribution of each process parameter and their combinations towards the strength of LMD Inconel 625 components. A confidence level of 90 % was used in this analysis.

Fig. 3. UTS and Elongation with RunOrder

A regression model based on the statistical analysis of the DoE results is presented in Eq. 1. This model has an adjusted R 2 of 57.69 %, which is a relatively low fit. This relatively low fit, may be explained by the lack of fit shown in the analysis of variance, with it accounting 28.94 %. From this analysis only two sources were found significant, both linear. These were Laser Power and Powder feed, with 21.53 % and 40.62 %, respectively. UTS = 764 . 5 − 0 . 0769 × LaserPower + 7 . 92 × PowderFeed (1) The obtained regression model was used to extrapolate the process parameters within a window of 1000 to 1600 W laser power and 7 to 15 g / min of powder feed. The maximum predicted UTS of 806.42 MPa is achieved with 1000 W