| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a method and an apparatus by which heating speed of a steel material, such as thick steel plate, is improved, and also, residual stress caused by heat treatment is reduced. SOLUTION: The heat treatment method for steel material is a method in which a steel material or the surface layer part is rapidly heated at >=2 deg.C/s heating rate with one heating method among an induction-heating, a laser- heating and a plasma-heating after completing hot-rolling. The surface layer part can be heated at a higher heating rate by >=0.5 deg.C/s than the center part in the plate thickness. The heat treatment apparatus for steel material is provided with heating means among one or more kinds of an induction-heating means, a laser-heating means and a plasma-heating means, and has the capacity rapidly heating the steel material at >=2 deg.C/s heating rate. Further, this heat treatment apparatus for steel material, is provided with one or more kinds among the solenoid type induction-heating means, the laser-heating means and the plasma heating means, or has the capacity rapidly heating the surface layer part of the steel material at higher heating rate by >=0.5 deg.C/s than the center part of the plate thickness.</p> |
