Enhancement of surface hardness and metallurgical properties of AISI 410 by laser hardening process; diode and Nd:YAG lasers

Abstract

This paper investigates the experimental study of laser surface hardening (LSH)of AISI 410 martensitic stainless steel by using two industrial lasers; 1600 W high power diode laser and 700 W Nd:YAG laser. The influence of the distribution and shape of the laser beam; Top-hat in diode laser and Gaussian distribution in Nd:YAG laser, have been investigated on the micro-hardness, geometrical dimensions of the hardened area (depth and width), microhardness deviation (MHD)from the base metal in width and depth of hardened layer, and the ferrite phase percentage. Microstructure evaluation of the laser hardened zones were performed using optical and FE-SEM. Results show that the diode laser creates a higher surface hardness, more depth and width of hardness, more MHD in depth and width and less ferrite phase than the Nd:YAG laser, which is because of lower wavelength of diode laser (808 nm)than Nd:YAG laser (1064 nm)that lead to higher laser energy absorption. Observations indicate that hardened layer of diode laser is about 620 HV0.3 with 1.8 mm depth, while for Nd:YAG laser is about 598 HV0.3 with 0.211 mm depth.