To provide a hot rolled steel sheet having excellent fatigue properties and an excellent balance in strength-stretch flange formability.
The hot rolled steel sheet having excellent fatigue properties and stretch flange formability has a composition comprising, by mass, 0.01 to 0.10% C, 2.0% Si and 0.5 to 2.5% Mn, and further comprising one or more kinds of elements selected from V, Nb, Ti, Mo, Zr and W by 0.01 to 0.30%, respectively, and also, satisfying equations (1) and (2), and the balance Fe with inevitable impurities; wherein a ferrite fraction is 90%, a ferrite grain size is 10 m, a precipitate average grain size r(nm) satisfies equation (3) (X(V-W) is expressed by equation (5)), and the average grain size r and a precipitation fraction f satisfy equation (4).
NOMURA MASAHIRO
MUKAI YOICHI
JP2001200339A | 2001-07-24 | |||
JP2002161340A | 2002-06-04 | |||
JP2000328186A | 2000-11-28 | |||
JPH06287685A | 1994-10-11 | |||
JPH06293910A | 1994-10-21 | |||
JP2003321748A | 2003-11-14 | |||
JPH11117039A | 1999-04-27 | |||
JP2004131802A | 2004-04-30 | |||
JP2002322539A | 2002-11-08 | |||
JP2004250749A | 2004-09-09 | |||
JP2004143518A | 2004-05-20 | |||
JP2006063360A | 2006-03-09 |
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