Steel sheet having excellent weldability

Abstract

Disclosed is a steel sheet, containing: Si: 0.20-2% (the term “%” herein means “mass %”, the same is true hereinbelow), Mn: 1-2.5%, a total mass of Si and Mn being 1.5% or more, and 0: 0.002% or less (exclusive of 0%), C: 0.02-0.25%, P: 0.1% or less (exclusive of 0%), S: 0.05% or less (exclusive of 0%), Al-0.02-0.2%, and N: 0.0015-0.015%. The steel sheet of the invention can be advantageously used for forming wide beads even in high-speed arc welding of 100 cm/min or higher.

1 . A steel sheet, comprising:
 Si: 0.20-2% (the term “%” herein means “mass %”, the same is true hereinbelow),   Mn: 1-2.5%, a total mass of Si and Mn being 1.5% or more, and   O: 0.002% or less (exclusive of 0%),   C: 0.02-0.25%,   P: 0.1% or less (exclusive of 0%),   S: 0.05% or less (exclusive of 0%),   Al: 0.02-0.2%, and   N: 0.0015-0.015%.   
   
   
       2 . The steel sheet of  claim 1 , wherein a thickness of an inner oxide layer existing in a surface layer of the steel sheet is 5 μm or less. 
   
   
       3 . The steel sheet of  claim 1  further comprising at least one element selected from the group consisting of Cr: 0.03-2%, Mo: 0.03-1%, and B: 0.0003-0.005%. 
   
   
       4 . The steel sheet of  claim 1  further comprising at least one element selected from the group consisting of Nb: 0.005-0.1%, Ti: 0.005-0.3%, V: 0.005-5%, and W: 0.005-0.5%. 
   
   
       5 . The steel sheet of  claim 1  further comprising Cu: 0.03-0.5% or less. 
   
   
       6 . The steel sheet of  claim 1  further comprising at least one of: Ca: 0.0005-0.005% and REM (rare earth elements): 0.0005-0.005%. 
   
   
       7 . The steel sheet of  claim 1  further comprising Zr and Mg: 0.0005-0.005% in total. 
   
   
       8 . The steel sheet of  claim 1  further comprising Co: 0.03-1%. 
   
   
       9 . The steel sheet of  claim 5  further comprising Ni: 0.015-0.5%.