Abstract: The effects of transformation hardening by laser heating were studied in AISI-01 tool steel by changing the laser operating parameter combinations and the initial microstructure. Some samples showed both melted and transformed areas while in others only transformation hardened regions were produced. These transformation hardened regions were studied with the help of optical and electron microscopy techniques, X-ray diffraction analysis and microhardness measurements. The results indicate that hardened case depths of about 0.3～0.6mm can be obtained by using laser beams that operate at a power of 400～600 Watts and a scanning rate range of 0.02～0.42cm/s. However, depending upon the power of the beam and its scanning rate different amounts of retained austenite and undissolved carbides were observed at the extreme outer surface. The results indicate that quenched and tempered samples of AISI-01 tool steel with initial hardness values in the range of 30～40HRC are more suited for laser hardening processing.

Key words: 残留奥氏体, 淬硬层组织, 激光处理工艺参数, 显微硬度分布, 原始组织