熱処理に伴う炭素鋼の組織変化 Change of Structure in Carbon Steels by Heat Treatment

We examined the change in metallurgical structure of cold-rolled carbon steels by heat-treatment. Specimens were three kinds of carbon steel of S10C, S25C and S50C. After repeating cold-rolling and heat-treatment at 700℃ or 900℃ in the atmosphere, the steel sheets were about 2mm in thickness. The oxide film on the surface was removed by mechanical abrasion, and the steel sheets were heat-treated at 700℃ or 900℃ in a vacuum. The steel sheets were cold-rolled to 0.5mm in thickness, and cut in size of 5mm×20mm. After the heat-treatment at 100-900℃ in a vacuum, The chemical etched surface of the specimens was observed by using scanning electron microscope. And, we measured Vickers hardness and X-ray diffraction pattern for the heat-treated specimens. The change in metallurgical structure of the carbon steel specimens was discussed on the basis of the heat-treatment temperature dependence of the Vickers hardness and the half-value width of the Fe(311) X-ray diffraction peak obtained by analyzing the X-ray diffraction pattern.