Nitrogenization

What is Nitrogenization?

Nitrogenization is a process that put steel (normally consists of Al, Cr, Mo) in NH3, keeping the temperature between 500℃—570℃ for a long time, which will form a layer of nitride ( always is Fe2N、Fe3N、Fe4N) with perfect hardeness and corrosion resistance. Generally, nitrogenization involves in gas nitriding, liquid nitriding and glow ion nitriding.

While nitriding, the carbon content of alloy steel is in commonly 0.2%-0.5%. And it depends on the mechanical properties of the core of part. The high carbon content will block the spread of N, thus reduce the thickness of the nitrided layer; And the high carbon causes large hardness gradient, resulting in that the nitrided layer is easy to peel. Al helps to increase the surface hardness after nitriding. And Cr can increase the thickness of the nitrided layer. Mo can avoid tempering brittleness when heated in 500 ℃-570 ℃ for a long time. Besides, Cr and Mo will improve material value.

General technological process of nitriding: forging, annealing, rough machining, quenched and tempered, finishing, nitriding. Plating with Ni, Sn, or Pb20%+Sn80% could prevent from nitriding.

Nitrogenization is Competetive.

Quenched and tempered treatment (QT) is needed before Nitriding, which will make it has good plasticity and toughness. Besides, the temperature of nitrogenization is kind of low, so the workpiece deformation is slight.

The surface hardness of the part goes up to HRC 65-72 after nitriding. Compared with carburizing, nitriding results in better wear resistance, corrosion resistance and higher hardness.