Steel

Abstract

According to an aspect of the present invention, there is provided a steel containing, by mass %, C: 0.08% to 0.12%, Si: 0.05% to 0.50%, Mn: 1.00% to 3.00%, P: 0.040% or less, S: 0.020% or less, Cr: 1.0% to 2.5%, Cu: 0.01% to 0.50%, Ni: 0.75% to 3.20%, Mo: 0.10% to 0.50%, Nb: 0.005% to 0.050%, Al: 0.010% to 0.100%, N: 0.0050% to 0.0150%, V: 0% to 0.300%, Ca: 0% to 0.0100%, Zr: 0% to 0.0100%, Mg: 0% to 0.0100%, and a remainder including Fe and impurities, in which a number density of Mn sulfides having an equivalent circle diameter of more than 5 m is 0 pieces/mm 2 to 10 pieces/mm 2 , and an average aspect ratio of the Mn sulfides having an equivalent circle diameter of 1.0 m to 5.0 μm is 1.0 or more and 10.0 or less.

1 . A steel comprising, by unit mass %,
 C: 0.08% to 0.12%;   Si: 0.05% to 0.50%;   Mn: 1.00% to 3.00%;   P: 0.040% or less;   S: 0.020% or less;   Cr: 1.00% to 2.50%;   Cu: 0.01% to 0.50%;   Ni: 0.75% to 3.20%;   Mo: 0.10% to 0.50%;   Nb: 0.005% to 0.050%;   Al: 0.010% to 0.100%;   N: 0.0050% to 0.0150%;   V: 0% to 0.300%;   Ca: 0% to 0.0100%;   Zr: 0% to 0.0100%;   Mg: 0% to 0.0100%; and   a remainder including Fe and impurities,   wherein a number density of Mn sulfides having an equivalent circle diameter of more than 5 μm is 0 pieces/mm 2  to 10 pieces/mm 2 , and   an average aspect ratio of the Mn sulfides having an equivalent circle diameter of 1.0 μm to 5.0 μm is 1.0 or more and 10.0 or less.   
     
     
         2 . The steel according to  claim 1  comprising, by unit mass %,
 V: 0.010% to 0.300%. 
 
     
     
         3 . The steel according to  claim 1  comprising, by unit mass %, one or more selected from the group consisting of
 Ca: 0.0005% to 0.0100%; 
 Zr: 0.0005% to 0.0100%; and 
 Mg: 0.0005% to 0.0100%. 
 
     
     
         4 . The steel according to  claim 2  comprising, by unit mass %, one or more selected from the group consisting of
 Ca: 0.0005% to 0.0100%; 
 Zr: 0.0005% to 0.0100%; and 
 Mg: 0.0005% to 0.0100%.