Experimental Investigation and Statistical Optimization of Dimensional Accuracy and Microhardness in Fiber Laser Cutting of Low-Carbon Steel Sheets

This study investigates the influence of process parameters on dimensional accuracy and microhardness in fiber laser cutting of low-carbon steel. A full factorial design of experiments (DOE) with three factors—cutting speed, focal position, and assist gas pressure—was applied to evaluate their effects on dimensional deviations and microhardness in the heat-affected zone (HAZ). The results showed that focal position is the most significant factor affecting all evaluated dimensional responses, while cutting speed has a strong influence on circular and linear dimensions. The effect of assist gas pressure was found to be response-dependent, being insignificant for inner diameter deviation but significant for selected linear features and through interaction effects with focal position. Statistical analysis confirmed the presence of significant interaction effects between process parameters. Microhardness measurements revealed a substantial increase in hardness from the base material toward the cut edge, indicating microstructural transformations caused by rapid thermal cycles during laser cutting. While this increase in hardness may enhance wear resistance, it may also lead to increased brittleness and reduced toughness. The findings provide a detailed insight into the relationship between process parameters and dimensional accuracy, highlighting the importance of parameter optimization and interaction effects in contributing to improved quality of laser-cut components.