- Volume 25 Issue 11
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Effect of Microstructural Factors on Room- and Low-Temperature Impact Toughness of Hypoeutectoid Steels with Ferrite-Pearlite Structure
페라이트-펄라이트 조직 아공석강의 상온 및 저온 충격 인성에 미치는 미세조직적 인자의 영향
- Lee, Seung-Yong (Department of Materials Science and Engineering, Seoul National University of Science and Technology) ;
- Jeong, Sang-Woo (Department of Materials Science and Engineering, Seoul National University of Science and Technology) ;
- Hwang, Byoungchul (Department of Materials Science and Engineering, Seoul National University of Science and Technology)
- Received : 2015.09.07
- Accepted : 2015.09.09
- Published : 2015.11.27
This paper presents a study on the room- and low-temperature impact toughness of hypoeutectoid steels with ferrite-pearlite structures. Six kinds of hypoeutectoid steel specimens were fabricated by varying the carbon content and austenitizing temperature to investigate the effect of microstructural factors such as pearlite volume fraction, interlamellar spacing, and cementite thickness on the impact toughness. The pearlite volume fraction usually increased with increasing carbon content and austenitizing temperature, while the pearlite interlamellar spacing and cementite thickness mostly decreased with increasing carbon content and austenitizing temperature. The 30C steel with medium pearlite volume fraction and higher manganese content, on the other hand, even though it had a higher volume fraction of pearlite than did the 20C steel, showed a better low-temperature toughness due to its having the lowest ductile-brittle transition temperature. This is because various microstructural factors in addition to the pearlite volume fraction largely affect the ductile-brittle transition temperature and low-temperature toughness of hypoeutectoid steels with ferrite-pearlite structure. In order to improve the room- and low-temperature impact toughness of hypoeutectoid steels with different ferrite-pearlite structures, therefore, more systematic studies are required to understand the effects of various microstructural factors on impact toughness, with a viewpoint of ductile-brittle transition temperature.
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