| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a technology suitable for enhancing the strength and toughness of a thin-walled low-carbon steel. <P>SOLUTION: The high-strength high-toughness thin-walled low-carbon steel is obtained by rapidly heating and rapidly cooling a thin-walled low-carbon steel which is a plain carbon steel having a thickness of 1.2 mm or less. In thus obtained steel, the microstructure is not uniform but forms a duplex grain structure in which crystal grains having different grain sizes are mixed, and preferably includes a hard phase structure in addition to the duplex grain structure. A duplex grain structure of crystal grains having a smaller grain size or a hard phase structure contained in the duplex grain structure is obtained by repeating a heat treatment step including rapid heating and rapid cooling a plurality of times, and consequently, a thin-walled low-carbon steel with higher strength and higher toughness is obtained. <P>COPYRIGHT: (C)2010,JPO&INPIT</p> |
