INVESTIGATIONS OF NITRIDATION BEHAVIOR OF HIGH-TEMPERATURE MATERIALS

Furnace rolls and inner tube walls of industrial bright annealing furn aces are often subject to attack by nitrogen atmospheres. In order to select appropriate materials for application in nitriding atmospheres, three commercial stainless steels (AISI 314, alloy DS, alloy 800H) an d four nickel base alloys (alloy 45-TM, alloy 600H, alloy 601H and all oy 602CA) with different concentrations of nickel, chromium, silicon a nd aluminium were exposed to both N-2/H-2 gas atmospheres at temperatu res of 1000 degrees C, 1100 degrees C and 1200 degrees C. The impact s trength, the mass change due to nitrogen pick-up and the depth of inte rnal nitridation were determined after exposure. At 1000 degrees C nit rogen pick-up and loss of impact strength, was low for all alloys inve stigated. At 1100 degrees C and 1200 degrees C, however. all alloys su ffered internal nitridation. Both internal nitridation and loss of duc tility were more severe in the iron base alloys than in the nickel-bas e alloys. The corrosion attack by nitridation decreased with increasin g nickel content. The highest resistance to nitridation was found in t he nickel base alloys 600 H and 602 CA.