# Influence of Laser Cutting Parameters on the Microhardness, Roughness, and Microstructure of AISI 304, S355J2, and AlMg3 Alloys

## TL;DR

This study compares how laser cutting affects the surface quality of three metals, showing that material-specific adjustments are needed for optimal results.

## Contribution

The paper provides original, comparative guidelines for laser cutting parameters tailored to specific materials.

## Key findings

- S355J2 steel shows the lowest surface roughness but significant surface hardening with microhardness up to 700 HV 0.1.
- AISI 304 steel exhibits superior thermal stability with no microstructural changes and moderate roughness.
- AlMg3 alloy develops a visible remelted layer and fine-grained microstructure with lower hardness and a diffuse heat-affected zone.

## Abstract

What are the main findings?
Optimal surface quality in laser beam cutting requires material-specific optimization of gas pressure.Laser beam cutting increases microhardness in the immediate cutting zone across all materials.AISI 304 steel shows the highest heat resistance, with no microstructural changes or melt zone observed.

Optimal surface quality in laser beam cutting requires material-specific optimization of gas pressure.

Laser beam cutting increases microhardness in the immediate cutting zone across all materials.

AISI 304 steel shows the highest heat resistance, with no microstructural changes or melt zone observed.

What are the implications of the main findings?
Gas pressure must be tailored to each material to achieve superior surface finish in industrial applications.Enhanced microhardness improves wear resistance but may affect ductility in the cut edge.AISI 304’s superior thermal stability makes it ideal for high-precision cutting processes requiring minimal distortion.

Gas pressure must be tailored to each material to achieve superior surface finish in industrial applications.

Enhanced microhardness improves wear resistance but may affect ductility in the cut edge.

AISI 304’s superior thermal stability makes it ideal for high-precision cutting processes requiring minimal distortion.

This study provides a comparative and material-specific assessment of how laser cutting parameters affect the surface integrity of three commonly used engineering alloys, thereby extending the current knowledge beyond single-material analyses. The main objective was to quantify and relate changes in surface roughness, microhardness, and microstructure to variations in laser cutting conditions for S355J2 steel, AISI 304 steel, and AlMg3 aluminum alloy. Variable cutting parameters were applied, including cutting speed, assist gas type and pressure, as well as laser beam power, and their combined effect on the thickness of the remelted and heat-affected zones was evaluated. The results show clear material-dependent trends: S355J2 steel exhibited the lowest surface roughness but the most pronounced surface hardening, with maximum microhardness values reaching approximately 700 HV 0.1 in a relatively narrow heat-affected zone, whereas AISI 304 showed a distinct edge-hardening effect with more moderate roughness. In contrast, the AlMg3 alloy developed a clearly visible remelted layer and a refined, fine-grained microstructure, accompanied by much lower hardness levels but a more diffuse heat-affected zone. These findings provide original, comparative guidelines for selecting laser cutting parameters tailored to specific materials, enabling the optimization of edge quality and surface properties in industrial applications.