The Kinetic Aspect of Nitriding in the Salt Bath (A Study on the Nitriding Process in Molten Salt, 2nd Report)

DOI Web Site Web Site

Bibliographic Information

Other Title
  • 塩浴窒化の速度論的考察
  • エンヨク チッカ ノ ソクドロンテキ コウサツ

Search this article

Abstract

The nitriding process for case hardening of steel is an excellent method having many advantages, but its greatest disadvantage is that it takes a long time. Recently, the rapid nitriding method in which molten salt containing cyanate is used has been employed in practice and it has been observed that the nitrided layer obtained, after treatment of only 2 or 3 hours at temperature between 550° and 570°C by this method, did not greatly differ from that obtained by the gas nitriding method in hardness and microstructure. However, the reason why molten salt promotes the nitriding reaction has not been clarified yet. From this point of view, we investigated into the cause of promotion of nitriding in by use of molten salt, in comparison with the gas nitriding method in which NH3 gas is used. From the results obtained the following conclusions may be drawn : (1) The accelerated nitriding reaction with molten salt can be explained by considering the nitrogen concentration at interface, i.e. in the case of nitriding with molten salt containing cyanate, nitrogen concentration at interface increases linearly as nitriding temperature becomes higher. (2) The nitriding reaction can be considerably promoted, when the nitriding treatment is carried out at temperature over 530°C. (3) It is probably possible to further reduce the nitriding time, by using the salt having more nitrogen concentration than that in this experiment.

Journal

Keywords

Details 詳細情報について

Report a problem

Back to top