| Summary: | 碩士 === 國立臺北科技大學 === 材料及資源工程系研究所 === 98 === High frequency induction heating and quenching is often used to surface harden steels. The process parameters of induction heating are greatly dependent on experience.
This study intends to vary specimen size (diameter 10,20 and 30mm), power (12.5,15,17.5 and 20kW), and time (15,20 seconds) for induction heat treatments using 50KHz high-frequency furnace . It is found that the most appropriate size for heat treatment is 20mm diameter bar. At power 12.5kW, surface exhibits large amount of ferrite indicating insufficient heating. Whilst at power 17.5 kW and 20kW, surface structure are mixed with bainite and martensite, they can all achieve similar surface hardness. The depth of hardened layer is over 5mm using 20kW power which does not meet surface hardening requirement. Through the diagram of hardening depth versus entering heat , a good rule of thumb for selecting induction heating parameters may be obtained.
Wear tests are also performed on the untreated, 15kW treated, and 17.5kW treated specimens. It is found that the specimen treated using 17.5kW power for 20 seconds obtain an optimal wear resistance because of uniform microstructure formation in the hardened layer.
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