Abstract
The authors studied the relative influences of C, Al and Cr contents in the Al-Cr steels up n the nitrided case as well as the mechanical properties before and after nitriding, and found that the good nitrided case having high hardness and moderate toughness is acquired in the steels of the following compositions; "Al 0.7-1.2%, Cr 0.8-1.5% and Al%<Cr%."
But even in the steels as the above compositions, their nitrided cases tend to show somewhat brittleness, as the contents of Al, Cr and C become higher. From the results of mechanical testing, a slight temperbrittleness was observed in Al-Cr steels by the prolonged heating of nitriding.
Therefore, the further investigation was carried out on the effect of the special elements upon the Al-Cr steel such as Ni, Mo, V and Cu, seperately or in any combination.
Researches were made on Al-Mo, Al-V, Cr-Mo, or Cr-V steels. And heat and corrosion resisting properties of nitrided case were also investigated on the above all steels.
