Improvement of corrosion resistance of Alloy 600 by utilizing recrystallization

Intergranular corrosion (IGC) of the recrystallized Alloy 600 containing 0.06%C has been investigated. Cold rolled Alloy 600 was recrystallized by electric furnace heating or by YAG (Yttrium-Aluminum-Garnet) laser irradiation. The IGC resistance was evaluated by Streicher test (JIS G 0572). It was observed that the cold rolled Alloy 600 of 45 to 75% are occupied by the recrystallized grains after the electric furnace heating at 800 to 900degC. The recrystallized Alloy 600 is excellent in IGC resistance, because of the granular Cr-rich carbides distribution in the recrystallized grains. It was shown that the surface recrystallized layer of about 300 to 800 μm thickness can be easily formed on the cold rolled Alloy 600 by the 900 W YAG laser irradiation. The IGC resistance of the surface recrystallized Alloy 600 is also excellent, except the excessive laser irradiation. (author)