| Title |
Effect of Microstructure on Thermal Fatigue Properties of Roll Materials ( Part 1. Evaluation of Thermal Fatigue Properties ) |
| Authors |
김도형(Do Hyung Kim); 류재화(Jae Hwa Ryu); 신기삼(Kee Sam Shin); 이성학(Sung Hak Lee) |
| Abstract |
Abstract The objective of the present study is to investigate thermal fatigue properties in three work rolls, i.e., Ni-grain cast iron roll, high Cr (Hi-Cr) cast iron roll, and high speed steel (HSS) roll. These three rolls ware manufactured by a centrifugal casting method. The basic microstructures of their shell regions were observed to be composed mainly of coarse primary carbides and tempered martensite matrix, and the amount of primary carbides was increased in the order of the HSS roll, the Hi-Cr roll, and the Ni-grain roll. The thermal fatigue test results indicated that thermal fatigue properties were the better in the order of the HSS roll, the Hi-Cr roll, and the Nigrain roll, and that the thermal fatigue life of each roll was decreased with increasing the mean temperature and with increasing the temperature range of the thermal fatigue cycle. These results were interpreted by the amount of primary carbides and by cyclic softening phenomena associated with the exposed time at elevated temperatures during the thermal fatigue test. |