Study on laser quenching of aircraft gears with rectangular beam based on multi-field coupling mechanism

The aircraft engine plays an important role in the aviation field, and the gear is the key part of the aircraft engine. During the service, the contact fatigue of the gears surface aggravates the gears surface wear and leads to the initiation of micro-cracks. Laser quenching surface heat treatment technology is one of the effective ways to strengthen the surface of aircraft gear. Due to the solid-state phase transition effect of laser quenching, the residual stress can be effectively controlled, the formation of micro-cracks on the gears surface can be reduced, and the uniform distribution of the quenching layer on the gears surface is realized. To enhance laser quenching efficiency and ensure precise process control, a rectangular laser heat source model was established. This model was based on the characteristics of actual laser processing heat sources. A numerical model coupling temperature, stress, and phase transition was developed for 12Cr2Ni4A aircraft gear double lap laser quenching, revealing the process's instantaneous evolution. The numerical simulation results show the temperature characteristics of laser quenching rapid heating and cooling, and residual stress concentration distribution phenomenon appears in the secondary tempering zone. The phase transformation results after quenching reveal the presence of a large amount of martensite in the quenching layer. Finally, the effectiveness of the numerical simulation was verified by the laser quenching experiment of the aircraft gear. The research on laser quenching of aircraft gears is crucial for improving their surface hardness, wear resistance, and extending their service life.