Product Code: ICA11_P101

Topography of Grain Boundaries Varied by Short Pulse Laser Irradiation for Controlling Microstructures of Metals
Authors:
Daisuke Tone, Graduate School of Engineering, Osaka University; Osaka Japan
Masahiro Tsukamoto, Joining and Welding Research Institute, Osaka University; Osaka Japan
Toshiya Shibayanagi, Joining and Welding Research Institute, Osaka University; Osaka Japan
Shinji Motokoshi, Institute for Laser Technology; Osaka Japan
Nobuyuki Abe, Joining and Welding Research Institute, Osaka University; Osaka Japan
Presented at ICALEO 2011

Controlling microstructures of metal is an important technology for production of new functional materials. Function of materials depends on their microstructures which include phase, shape and size of grains, grain orientation and grain boundary structure. In our previous study, we developed a fiber laser irradiation system in order to modify microstructures of metal by the laser local heating of grains. To obtain new functions by controlling the microstructures, selecting grains before the laser local heating is important. However, the grains were not selected since the grain boundaries could not be visualized in the system. We focused on difference of melting point between the grains and the grain boundaries. It is known that melting point of the grain boundaries is lower than that of the grains. During short pulse laser irradiation, the grain boundaries visualization might be caused by slight variation of the surface topography due to the difference of melting point. In this study, stainless steel plate was irradiated with a nanosecond laser. After the laser irradiation, topography of the grain boundaries was observed with an atomic force microscope. Topography of the grain boundaries was varied as number of the laser pulses was increased.