pISSN : 1598-706X / eISSN : 2288-8381
한국주조공학회지 (16권2호 109-115)
Effect of Matrix Structures on the Fracture Characteristics of Austempered C/V Graphite Iron
오스템퍼링처리한 C/V흑연주철의 파괴특성에 미치는 기지조직의 영향에 관한 연구
Chang-Gyu Kim, Hong-Beum Kim*, Chang-OcK Choi*
Pusan National University of Technology, *Dong-A University
Effect of various austempered structures on fracture characteristics of C/V graphite cast iron has studied. The tensile strength and hardness reached the maximum value of 971.4MPa and HB302 at the austempering temperature of 250℃, respectively. As the austempering temperature increased, the amount of retained austenite increased from 18% to 22, 29%, while K_{IC} values ranged from the value of 65MPa•m^{12} to 70MPa•m^{1/2}, 66MPa•m^{1/2}. This fact that K_{IC} value was not sensitive to the increase of the amount of the retained austenite was that K_{IC} was dependent on the matrix structure in lower bainitic matrix, while dependent on the notch effect from C/V graphite shape in upper bainitic matrix. Fractured surfaces showed a ductile fracture pattern at 300℃. Very large coalescence by C/V graphite and relatively small voids by spheroidal graphite were observed.
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