低炭素キルド鋼のコントロールド・ローリングの基礎研究

抄録

Three factors, namely, grain size, pearlite, and precipitation hardening have been chosen out of many factors contributing to the mechanical properties of hot rolled steel plates to study how hot rolling affects to the th ree factors and how hot rolling influences to the strength and touhness throughout them.
The results are as follows:
(i) The austenite/ferrite transformation behaviour changes by rolling temperature and Can be-classified. systematically. Especially, ferrite transformation is much promoted by large deibrmation in low temper ature.
(ii) The increase of pearlite volume fraction is clearly detrimental to the toughness in coarse grained steels but not so harmful in grain refined steels. And also the banding of pearlite by hot rolling seems to give a favourable effect on toughness.
(iii) The precipitation hardening with V or Nb raises charpy transition temperature, in the case of high finishing temperature, but not at low finishing temperature.
(iv) It is shown that the strength and toughness of hot rolled steel plates are affected by many factors and that the contribution of each factor varies considerably by rolling conditions.