## 4 Results and Discussion
### Temperature Distribution  
Understanding the inherent features of SLM processes, such as temperature distribution and molten pool size, is essential before processing. These characteristics influence the physical properties and the overall quality of the resulting products. The effect of laser power and scan speed to temperature distribution along three different directions is shown in Figures 10-12.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Quantity**} & \multirow{2}{*}{**[PERSON] et al. [10]**} & \multirow{2}{*}{**[PERSON] and [PERSON] [14]**} & \multicolumn{2}{c}{**Our Results**} \\ \cline{3-4}  & & & **Model 1** & **Model 2** \\ \hline Length (mm) & 0.300 & 0.226 & 0.284 & 0.383 \\ Width (mm) & 0.200 & 0.180 & 0.122 & 0.102 \\ Depth (mm) & 0.070 & 0.068 & 0.063 & 0.054 \\ Max. temperature (K) & 4900 & 3005 & 2818 & 2699 \\ \hline \hline \end{tabular}
\end{table}
Table 4: Comparison of the maximum temperature and size of molten pool.  
Figure 8: Cross-sectional temperature distribution with \(P=45\) and \(v=120\).  
Figure 9: Temperature distribution with \(P=45\) and \(v=120\). **(a)** Model 1; **(b)** Model 2.  
Figure 11: _Cont._  
Figure 10: Temperature distribution along z-axis. (**a**) Laser power = 45 W; (**b**) Scan speed = 120 mm/s.  
Figure 10 shows that the maximum temperature appears at the top of the powder surface, as depicted along the z-axis. This makes sense, since it is the place where the laser beam irradiates. Under the same laser power, a 33% change (\(\pm\)40 mm/s) of scan speed does not significantly change in maximum temperature for Model 1, while the change in maximum temperature for Model 2 is about 10%. Under the same scan speed, a 22% change in laser power (45 \(\pm\) 10 W) affects the maximum temperature proportionally by  
Figure 11: Temperature distribution along y-axis. (**a**) Laser power = 45 W; (**b**) Scan speed = 120 mm/s.  
Figure 12: Temperature distribution along \(\xi\)-axis. (**a**) Laser power = 45 W; (**b**) Scan speed = 120 mm/s.  
about 9%. This reveals that the depth of the molten pool is more sensitive to laser power than scan speed.  
Figure 11 shows that the molten size along the y direction increases with an increase in laser power and a decrease in scan speed, however, not significantly. Figure 12 illustrates the temperature along the \(\xi\)-axis. Figure 13 shows the change in pool length along the \(\xi\)-axis with different laser power and scan speed. It reveals that an increase in scan speed significantly increases the pool length along the \(\xi\)-axis under the same laser power. As the scan speed increases from 80 mm/s to 160 mm/s, the pool length increases by 26.8% and 12% for heat source Models I and II, respectively. Owing to a similar total heat absorption of the power bed, the corresponding pool width, depth, and maximum temperature decrease.  
Based on the observation that, under the same amount of heat energy, the temperature predicted using Model 1 is much higher than in Model 2, (because the heat source of Model 2 is more widely distributed than Model 1) this causes the predicted temperature to disperse more easily and results in the lower temperature performance.