To provide a precursory steel of a high strength ultrafine-grained steel in which deterioration in toughness and deterioration in machinability as problems when the increase of its strength is attained by the fining of ferrite grains can be suppressed.
The precursory steel of an S-containing high strength fine-grained steel has a structure composed of ferrite with the average grain diameter of ≤10 μm and at least one or more kinds selected from austenite, pearlite, cementite and martensite, comprises, by mass, 0.3 to 0.5% C (carbon), 0.1 to 0.3% S (sulfur), ≤0.8% Si and 0.05 to 3.0% Mn, and the balance Fe with inevitable impurities, and has a fine-grained structure with the average grain diameter of ≤3 μm.
COPYRIGHT: (C)2008,JPO&INPIT
FURUYA YOSHIYUKI
MATSUOKA SABURO
TORITSUKA SHIRO
NAGAI HISASHI
| JP2001073035A | 2001-03-21 | |||
| JP2003147482A | 2003-05-21 | |||
| JP2001073035A | 2001-03-21 | |||
| JP2003147482A | 2003-05-21 |