Nitridable Steels,Nitridable Steels,Nitridable Steels,Nitridable Steels,Nitridable Steels
Of the alloying elements commonly used in commercial steels, aluminum, chromium, vanadium,
tungsten, and molybdenum are beneficial in nitriding because they form nitrides that are stable at nitriding temperatures.
Molybdenum, in addition to its contribution as a nitride former, also reduces the risk of embrittlement at nitriding
temperatures. Other alloying elements, such as nickel, copper, silicon, and manganese, have little, if any, effect on
nitriding characteristics.
Although at suitable temperatures all steels are capable of forming iron nitrides in the presence of nascent nitrogen, the
nitriding results are more favorable in those steels that contain one or more of the major nitride-forming alloying
elements. Because aluminum is the strongest nitride former of the common alloying elements, aluminum-containing
steels (0.85 to 1.50% Al) yield the best nitriding results in terms of total alloy content. Chromium-containing steels can
approximate these results if their chromium content is high enough. Unalloyed carbon steels are not well suited to gas
nitriding because they form an extremely brittle case that spalls readily, and the hardness increase in the diffusion zone is
small.
The following steels can be gas nitrided for specific applications:
· Aluminum-containing low-alloy steels (Table 1)
· Medium-carbon, chromium-containing low-alloy steels of the 4100, 4300, 5100, 6100, 8600, 8700, and
9800 series
· Hot-work die steels containing 5% chromium such as H11, H12, and H13
· Low-carbon, chromium-containing low-alloy steels of the 3300, 8600, and 9300 series
· Air-hardening tool steels such as A-2, A-6, D-2, D-3, and S-7
· High-speed tool steels such as M-2 and M-4
· Nitronic stainless steels such as 30, 40, 50, and 60
· Ferritic and martensitic stainless steels of the 400 and 500 series
· Austenitic stainless steels of the 200 and 300 series
· Precipitation-hardening stainless steels such as 13-8 PH, 15-5 PH, 17-4 PH, 17-7 PH, A-286, AM350,
and AM355

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