ISSN 2594-5327
49º Congresso anual — Vol. 49, Num. 1 (1994)
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Resumo
The toughness of surface-treated microstructures constitutes a compromise between the hard, brittle case and the softer, ductile core. Bending tests are helpful in determining the toughness of such microstructures. Essential parameters are the case and core properties and the microstructure distribution. In nitrocarburizing, two to four hours of treatment generally produce a sufficient nitriding effect on any required component performance, with minor variations in compound layer thickness and nitriding case depths. Therefore, the influence of the core microstructure is predominant. Tempered or annealed microstructures have higher toughness than normalized microstructures, and alloyed steels perform marginally better than plain carbon steels. The bending crack stress describes compound layer properties and may be used to indicate bending fatigue crack initiation. Equal nitriding leads to higher bending crack stress in alloyed steels. Gas nitriding requires up to 120 hours of treatment, thus causing wider variations in the case microstructures. Above all, prolonged nitriding times cause a distinct change in the core microstructure and very often lead to its embrittlement. The influence of the nitriding parameters and of the alloy composition of the steels on the toughness is therefore greater during nitriding.
Palavras-chave
nitriding, nitrocarburizing, surface treatment, toughness, microstructure, bending crack stress
Como citar
GROSCH, JOHANN.
Toughness of Nitrided and Nitrocarburized Microstructures,
p. 3731-3744.
In: 49º Congresso anual,
Rio de Janeiro, Brasil,
1994.
ISSN: 2594-5327, DOI 10.5151/2594-5327-49v8-213-226
