METHOD FOR GRAIN REFINING OF STEEL AND STEEL ALLOY STRUCTURE BY HIGH-FREQUENCY INDUCTION HEATING, GRAIN-REFINING APPARATUS FOR THE SAME, METHOD FOR WORKING METALLIC STRUCTURE, AND METALLIC STRUCTURE

摘要

PROBLEM TO BE SOLVED: To provide a method for grain refining of steel and steel alloy structures which provides excellent workability, safety, and cost effectiveness, and can prolong the fatigue life of metallic materials and an apparatus for the same.

SOLUTION: The structures of the steel and steel alloys are refined in grains by using high-frequency induction heating as a means for heating the steel and steel alloys and by repeating heating and cooling in a temperature range where the steel and steel alloy surfaces do not melt. The heating is performed by a coil 3 for heating to which a high-frequency electric current is supplied from a high frequency matching transformer 2 and the cooling is performed by a cooling nozzle 7 to which water and air are supplied from a cooling unit 8. The number of times at which the high-frequency induction heating is performed is preferably from 1 to 20 times. The frequency of the high-frequency induction heating is preferably selected in a range from 10 to 1,000kHz. Also, the heating rate in heating is from 100 to 1,000°C/sec and the cooling rate is preferably from 10 to 800°C/sec.

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