Papers by Keyword: Austenite Grain Coarsening

Abstract: The austenite grain coarsening behavior of low carbon (0.13% C) structural steels containing chromium and nickel singly or in combination were studied by heating the steels at successive high temperature in the austenite zone in the temperature range of 900-1100°C with an interval of 50°C. The carburizing technique has been adopted to reveal the prior austenite grain boundaries and mean linear intercept method was used to measure the austenite grain size.It was found that on heating the undissolved particles of chromium carbide, Cr₂C refine the austenite grain size at temperature below 1000°C, but the effect decreases with increasing temperature. Nickel does not produce any austenite grain refinement. In the presence of nickel particles of chromium carbide are less effective than chromium carbide particles in the absence of nickel in the refinement of austenite grain size.

Abstract: It is important to suppress grain coarsening during the carburizing treatment of automobile components such as gears and shafts so that high strength is maintained and heat treatment distortion is minimized. Two manufacturing methods are often used for the cost reduction. One is the increasing carburizing temperature. The other is the adoption of cold forging instead of hot forging. These methods are likely to result in grain coarsening in the case of conventional steels. It is well known that the key factors to control the grain growth are the initial austenite grain size and the volume and mean size of precipitates. In this study, the grain growth property of Ti-modified steel was investigated to confirm the influence of precipitates, and compared with those of Nb-modified and conventional steels. The influence of forging temperature on the grain growth property in a Ti-modified steel was also investigated.