Effects of Laser Shock Processing on the Mechanical Properties of 6061-T6 Aluminium Alloy Using Nanosecond and Picosecond Laser Pulses

Laser shock processing (LSP) is a surface treatment technique used to enhance mechanical properties such as hardness, corrosion resistance, and wear resistance. This study investigates the effects of LSP on a 6061-T6 aluminium alloy using four treatment conditions: nanosecond (ns-LSP), picosecond (ps-LSP), and a combination of nanosecond-picosecond (nsps-LSP) and picosecond-nanosecond (psns-LSP) pulses. Two laser systems were employed: a Q-switched Nd:YAG laser (850 mJ/pulse, 6 ns, 1064 nm, 10 Hz), and an Ekspla Atlantic 355-60 laser (0.110 mJ/pulse, 13 ps, 1064 nm, 1 kHz). All treatments induced compressive residual stresses up to 1 mm in depth. Additionally, improvements in microhardness were observed, particularly at deeper layers in the combined nsps-LSP treatment. Surface roughness was measured and compared. Among all configurations, the nsps-LSP treatment produced the highest compressive residual stresses (428 MPa) and greater microhardness at depth. These results suggest that the combined nsps-LSP treatment represents a promising approach to enhance the mechanical performance of metallic components.