| Summary: | 碩士 === 國立臺灣大學 === 機械工程學研究所 === 92 === Abstract
The characteristics of high frequency induction heating were that it could heat the surface of metal workpiece at a specific part quickly. The time of heating was so short that the oxidation and decarburization were negligible. This article used these features of high frequency induction heating to strengthen the metal workpiece. This experiment includes two parts: 1. To harden the tip of the sewing needle, which was manufactured from SK4 carbon tool steel. In order to make the sewing needle possessing toughness and partial high hardness, double quenching was performed in this experiment and the parameters affecting the hardness distribution and microstructure of the needles were discussed. The parameters were that whether using partial quenching or not and the different time holding in quenching temperature. 2. Workpiece could be heated quickly and reach to high temperature by high frequency induction heating. To make use of these characteristics, low-carbon steel was carburized in a short time at high temperature. Carburizing time and temperature are variables of this experiment. The parameters affecting the hardness distribution, microstructure, and carburization depth were discussed. The major results are shown as follows:
1. It would indeed get the result of tough needle and hard pinpoint when the sewing needle was hardened locally by high frequency induction heating in advance, because more Fe3C of the pinpoint would be dissolved into the matrix.
2. When low-carbon steel was heated by high frequency induction heating and carburized at high temperature for seconds, the speed of carburization was very fast. In addition, the effect of surface hardening was very good after quenching. Compared with the traditional method, this new method saves more time than the old one.
3. When high frequency induction heating was used in gas carburization, the Ledeburite would be developed in the surface if the carburizing temperature is above the eutectic point of cast iron. It may be useful in the surface modification of steel because of high hardness, good wear resistance and corrosion resistance.
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