과공석강에서 합금원소 Cr, Si 첨가 및 상변태 온도가 미세조직 변화와 인장성질에 미치는 영향 |
박정훈, 정신웅, 남원종 |
국민대학교 신소재공학과 |
The Effects of Alloying Elements, Cr, Si, and Transformation Temperature on the Microstructures and Tensile Properties of Hyper-Eutectoid Steels |
Jung Hoon Park, Shin Woong Jeong, Won Jong Nam |
School of Advanced Materials Engineering, Kookmin University, Seoul 02707, Republic of Korea |
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Received: 1 December 2016; Accepted: 7 February 2017. Published online: 4 July 2017. |
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ABSTRACT |
The effects of alloying elements, especially Cr and Si, and transformation temperature on the microstructures and mechanical properties of hyper-eutectoid steels were investigated. Increases in Si and Cr changed the morphology of cementite in upper bainite, while the morphology of pearlite seemed to be unchanged by the amount of alloying elements, except for variation in interlamellar spacing. Increasing Si and Cr content also caused increases in tensile strength and a reduction of area of the steels containing pearlitic microstructure, while decreasing tensile strength and reduction of area in steels transformed into upper bainitic microstructure. The tensile strength of steels consisting of pearlite, upper bainite and a mixture of pearlite and upper bainite, can be expressed with the equation σ= (σpo+kp·λp-1/2)·Vp+(σubo+kub·λub-1/2)·Vub. The values calculated using the above equation coincided well with the measured tensile strength of hyper-eutectoid steels containing Cr and Si. |
Keywords:
isothermal transformation, hyper-eutectoid steel, pearlite, upper bainite |
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