Comparative study of plasma nitriding and plasma oxynitriding for optimal wear and corrosion resistance: Influences of gas composition

The phase structures, microstructures, wear properties, and corrosion resistance of plasma nitrided and plasma oxynitrided 4140 steel were studied. The plasma nitriding was conducted on a mixture of nitrogen and hydrogen at 520 °C. Additional oxygen in the form of plain air was added during oxynitriding treatment in a fixed ratio of nitrogen and hydrogen at 520 °C. The influences of gas composition on properties of the nitrided layer and...