Mechanical behaviour of mild steel during multi-scan laser bending with forced cooling

Abstract

Laser bending is an innovative sheet metal forming technique. Researchers are focusing optimizing the process for enhancing bend angles and mechanical properties. To achieve this, a waiting period between laser scans is vital to re-establish the temperature gradient and improve bend angles. Forced cooling is a critical element in reducing this waiting time. This study investigates the influence of cooling environments (natural and forced cooling) during laser bending of mild steel sheets. It examines the impact of key parameters such as laser power, scan speed, and beam diameter under both cooling conditions. The results reveal that under forced cooling, specific combinations of process variables lead to exceptional outcomes. Notably, a bend angle of 8.81° is achieved with higher laser power (1000 W) and slower scan speed (1000 mm/min) in forced cooling condition. This study also analyzes temperature variations concerning laser power, scan speed, beam diameter, and the number of scans. Furthermore, under forced cooling conditions, an increase in ultimate tensile strength and micro-hardness is observed within the irradiated region. The highest micro-hardness value of 198.5 HV, was attained under forced cooling conditions at 1000 W of laser power and a scan speed of 1000 mm/min. This research underscores the potential of forced cooling mechanisms to significantly enhance laser bending outcomes, encompassing both bend angles and material properties.