Vergleichende Untersuchungen über die Aufstickung von niedrig- und hochlegierten Stählen sowie der Legierung NiMo 16 CrW in Ammoniak bei 300 bis 500°C

Comparative investigations into the nitruration between low and high alloy steels and the alloy NiMo 16 CrW in ammonia at 300 to 5OO°C The nitriding behaviour of high temperature high strength steels 13 CrMo 44, 10 CrMo 910 and 17 CrMoV 10, of the high alloy high temperature strength steels X 8 CrNiNb 16 13, the stainless steel Y 8 Cr 17 and nickel base alloy NiMo 16 CrW has been studied in ammonia at 300, 400 and 5OO°C, test durations being up to 1000 hours. The evaluation was based on determination of the nitriding depth preferentially with the aid of microhardness measurements. The structure of nitride layers and the structure changes due to nitrogen adsorption in the material are explained in connection with the time dependence of nitriding. The behaviour of specimens Passivated in air is shown as well as the influence of the surface pretreatment by depassivation or preoxidation and the influence of minor oxidising constituents (air, steam) in ammonia.