| 摘要 |
A grinding rod chemistry enhances wearability and durability of a steel rod and comprises levels of carbon to achieve a surface hardness in excess of 55 Rockwell C and levels of chromium which achieve significant depth in the formed outer martensite shell. The grinding rod has a core greater than 99% pearlite with a hardness less than 45 Rockwell C and the end portions of the rod are soft and have a hardness less than 35 Rockwell C. The steel bar of the selected chemistry is treated by reheating to above its austenitising temperature, transferring with minimal cooling to an open tubular quench vessel while securing the bar in the vessel to minimize bar warping, introducing quench water into the inlet end of the vessel and passing the liquid through the vessel to ensure uniform heat removal. The outer martensite shell is tempered by allowing the bar to soak back after quenching. The bar end portions are reheated in a furnace to elevate the end portions above the austenitising temperature and air cooling each end portion to provide the engineered end portion hardness of less than 35 Rockwell C.
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