Comparison of active screen and conventional plasma nitrided 30CrNiMo8 low-alloy steel

Active screen plasma nitriding is a promising surface modification technique that has many advantages over the conventional D C plasma nitriding (CPN). Behavior of 30CrNiMo8 Low-alloy steel has been compared under varying conditions of Active screen plasma nitriding and CPN processes. The process variables included active screen setup parameters (top lid and screen hole size), treatment temperature (550 and 580 centigrade), gas mixture (fixed for 75/25 of N2/H2) and treatment time (5h) in 500 Pa pressure for 5h. The structure and phases composition of the compound layer was studied by X-ray diffraction, microhardness tests, light optical microscopy and scanning electron microscopy. It was observed that Active screen plasma nitriding treated sample surfaces for both screen and iron plate top lid consist of y' and E phases and while the temperature and/or hole size of screen setup increased, the intensity of E phase in the compound layer increased. 'The results show that ion transition via sputtering and recondensation mechanism of screen top lid on the sample surface can be affected on the hardness and layer thickness. It appears that the AS plasma nitriding process facilitated the formation of ε phase in this test