| 摘要 |
A steel for a boiler excellent in butt seam weldability characterized in that it has a composition that C: 0.01 to 0.20 %, Si: 0.01 to 1.0 %, Mn: 0.10 to 2.0 %, Cr: 0 %, or 0.5 to 3.5 %, P: </= 0.030 %, S: </= 0.010 %, O: </= 0.020 %, with the proviso that 0.005 </= (Si%)/(Mn%) </= 1.5 when Cr is not contained, and 0.005 </=(Si%)/(Mn% + Cr%) </= 1.5 when Cr content is 0.5 to 3.5 %, and balance: Fe and inevitable impurities, and in that a mixed oxide of SiO2 and MnO or a mixed oxide of SiO2, MnO and Cr2 O3 formed during welding has a melting temperature of 1600 DEG C or less; and an electroseamed steel pipe for a boiler having reduced weld flaw. The above mentioned low melting point of the mixed oxide leads to the fusion of oxides formed during welding, and hence allows the oxides to be squeezed out as a slag, which provides excellent weldability of such a steel. The above steel for a boiler also exhibits a high creep rupture strength under a condition of a high temperature and a long time, and can be used for producing an electroseamed steel pipe for a boiler having reduced weld flaw and exhibiting excellent creep rupture strength and toughness.
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| 申请人 |
NIPPON STEEL CORPORATION;MURAKI, TARO;HASEGAWA, YASUSHI;OKAMOTO, JUNICHI |
发明人 |
MURAKI, TARO;HASEGAWA, YASUSHI;OKAMOTO, JUNICHI |
