The secret of hardness: is nitriding itself enough?
febbraio 12, 2025
Have you ever had problems achieving the desired hardness after a nitriding treatment? If you think that just carrying out the process will get 700 HV on a steel like 42CrMo4, you might be disappointed. The reason is simple: nitriding only works if the starting material has the right characteristics.
Why has hardness not been achieved after nitriding?
I recently analyzed an interesting case: a shaft made of 42CrMo4, intended for a mechanical application, had to be nitrided to reach 700 HV. However, after the treatment, the hardness obtained was lower. The cause? The starting material did not have sufficient strength. To obtain 700 HV, 42CrMo4 must have a strength of at least 1000-1100 N/mm². If this condition is not met, the result will be unsatisfactory.
Nitriding is a thermochemical treatment that enriches the surface with nitrogen, improving its wear resistance and hardness. However, its effectiveness depends on the composition of the material and its metallurgical state. If the material does not have an adequate basic resistance, the nitrided layer will not have the desired mechanical characteristics.
The production cycle: every phase counts
A common mistake is to think that nitriding alone can solve everything, but the reality is different. 42CrMo4, for example, is a very popular steel for its high resistance and toughness, but to obtain the best results it must be subjected to hardening before nitriding. Hardening, which consists of quenching and tempering, brings the steel to the right resistance, preparing the material for the surface treatment.
This principle does not only apply to nitriding, but to many other processes in the gear and mechanical sectors. An error in the choice of material or in the preliminary treatments can compromise the entire production cycle, with consequences on times and costs.
Have you ever faced a similar problem? Contact us to find out how to optimize the treatments on your mechanical components.
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