| 摘要 |
In this steel material satisfying a predetermined chemical composition and having a remainder comprising iron and unavoidable impurities, a complex oxide is contained containing REM, Zr, Ti, Al, Ca, and S, the complex oxide has no greater than 5.0/mm2 of oxides having a circle-equivalent diameter of greater than 3 μm, and with respect to complex oxides having a circle-equivalent diameter of 0.1-3 μm, there are at least 100/mm2 of complex oxides satisfying formula (1), and furthermore the average composition of the complex oxides that are 0.1-3 μm satisfying formula (1) is such that there is no greater than 20% of Al2O3, 3-20% of TiO2, 5-50% of ZrO2, 5-50% of REM oxide, 5-50% of CaO, and 1-15% of S. 0.008 ≤ (1/d)×{mass%S/(mass%CaO + mass%REM2O3)} ≤ 0.289 …(1) (where d is the circle-equivalent diameter of each complex oxide, and is 0.1-3 μm) |
