Nitriding Behavior and Strengthening Mechanism of Ti Added Steels
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Published:2007-03
Issue:
Volume:539-543
Page:4179-4184
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ISSN:1662-9752
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Container-title:Materials Science Forum
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language:
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Short-container-title:MSF
Author:
Kusumi K.1,
Senuma Takehide2,
Suehiro M.3,
Sugiyama Masaaki1
Affiliation:
1. Nippon Steel Corporation
2. Okayama University
3. Nippon Steel and Sumitomo Metal Corporation
Abstract
The nitriding process is one of the common methods for surface hardening, and consists of heat
treatment in a furnace for many hours. The nitriding behavior and strengthening mechanism of Ti added
steels in the nitriding process, which is applicable to a high temperature and rapid process such as the
continuous annealing of steel strip, were investigated.
The sheets were hardened only near the surface. The hardening of the surface layer is due to the formation
of clusters or fine precipitates with disc-like shape consisting of titanium and nitrogen. The maximum
hardness depends on the content of Ti in the steel while the annealing time and the concentration of NH3
influence the depth of the hardened zone affected by nitriding. It is thought that the hardening only near
surface improve bending stiffness without significant increase of yield stress. So there is a possibility that the
surface hardening improves the dent resistance of automobile outer panels without significant worsening of
the surface deflection.
To study these behaviors theoretically, a model for predicting the precipitation behavior due to nitriding has
been developed. The experimental results can be reasonably explained by the model calculations. And also,
the estimation of the amount of strengthening was carried out. It indicated that the strengthening mechanism
is mainly the precipitation hardening of TiN that could be Ti nitrides or Ti-N clusters.
Publisher
Trans Tech Publications, Ltd.
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics,General Materials Science
Cited by
1 articles.
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