High temperature oxidation behaviour of laser alloyed ferritic steels

The high temperature oxidation behaviour of low alloy ferritic steels, viz., 2.25Cr-1Mo steel and 9Cr-1Mo steel, coated with Cr, followed by laser irradiation have been investigated. Chromium powder was deposited by two different techniques i.e. plasma spraying, and direct powder feeding method. For the laser treatment, a 3 kW continuous wave (CW) CO2 laser with line focus mode was used. Detailed characterization of the coated and laser alloyed samples was carried out using optical microscope, and SEM/EDAX. The oxidation tests were carried out at 700 degrees C and 800 degrees C in air. Laser alloyed 2.25Cr-1Mo and 9Cr-1Mo steels showed improved oxidation resistance compared to as-coated and un-coated specimens.