超高頻感應加熱於工件局部熱處理上的應用

摘要高週波感應加熱的特徵為：在很短的時間內，可以讓工件表面的溫度升到很高；加熱的時間極短，且可進行局部加熱。本文乃利用高週波感應加熱的這些特點，來實施工件的局部強化處理。實驗分兩部分進行：1.對以SK4碳工具鋼為材料的縫紉針進行局部硬化處理，為了使縫紉針能兼具韌性和針尖局部高硬度的要求，嘗試以兩次淬火（針尖局部淬火→淬火→回火）來改良其機械性質，實驗中探討有無局部淬火、局部淬火時的持溫時間等參數對其硬度分佈及顯微組織等的影響。2.利用高週波感應加熱快速且溫度高的特點，對低碳鋼進行快速滲碳，想要了解在高溫短時間的滲碳情形，探討滲碳溫度、滲碳時間等參數對其滲碳深度、顯微組織及淬火後的硬度分布等的影響。所得結果如下： 1. 碳工具鋼縫紉針事先以高週波對針尖做局部硬化處理，在針尖處能有效固溶更多的Fe3C於基地內，經二次淬火及回火後，的確能達到針身韌而針尖硬的效果。 2. 低碳鋼以高週波感應加熱，施以高溫短時間的滲碳處理，其滲碳速率相當快，且淬火後表層硬化效果良好。與傳統的滲碳方法比較，可以顯著節省滲碳時間。 3. 以高週波感應加熱實施滲碳處理，在滲碳溫度超過白鑄鐵的共晶溫度（1148℃）時，工件表面會有粒滴斑鐵組織產生，其硬度高、耐磨耗且耐蝕性良好，在鋼料表面改質處理上的應用，頗具潛力。

關鍵字

SK4碳工具鋼；高週波感應加熱；局部硬化

並列摘要

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.

並列關鍵字

SK4 carbon tool ； High frequency induction heating

參考文獻

5.Bennighoff,W.E, and Osborn, H.B., “Practical Aspects of the Selection of Frequency and Time Cycles for the Processing of Metallic Parts with Induction Heating”,Trans., A.S.M. Vol.34（1945）pp.310-350.

參考文獻