Abstract: In order to improve the hardness and wear resistance of screwdriver head and prolong its service life, based on the pre-test of laser quenching thin-walled parts, laser quenching test was carried out on screwdriver cutting edge with high power fiber coupled semiconductor laser. Microstructure, microhardness and wear resistance of the laser quenched area of cutting edge were analyzed by means of optical microscope, microhardness meter and friction and wear tester, and the feasible process parameters of laser quenching for the screwdriver cutting edge were determined. The experimental results show that after laser quenching, the cutting edge consists of three parts: the completely hardened zone, the transition zone and the base material. The microstructure of the completely hardened zone is composed of needle-shaped martensite and retained austenite, and the transition zone is composed of martensite and tempered sorbite. The reasonable process parameters of the laser quenching for cutting edge are laser power 600 W and scanning speed 900 mm/min. After laser quenching, the average hardness of the edge section is 805.7 HV0.3, which is 177.4 HV0.3 higher than that before quenching; and the surface hardness value is 816.7 HV0.3, which is 188.4 HV0.3 higher than that before quenching. After quenching, the surface abrasion loss of the cutting edge is 0.5 mg, which is 27.8% of that of the substrate, and the stable friction coefficient is 0.25, which is 65.8% of that of the substrate. The laser quenching process can effectively improve the microhardness and wear resistance of the screwdriver cutting edge, and can be used to strengthen the surface performance of the screwdriver blade.

Key words: laser quenching, screwdriver cutting edge strengthening, microstructure, microhardness, wear resistance