Steel material
View Patent ↗A steel material contains: by mass %, C: greater than 0.05% to 0.18%; Mn: 1% to 3%; Si: greater than 0.5% to 1.8%; Al: 0.01% to 0.5%; N: 0.001% to 0.015%; one or both of V and Ti: 0.01% to 0.3% in total; Cr: 0% to 0.25%; Mo: 0% to 0.35%; a balance: Fe and impurities; and 80% or more of bainite by area %, and 5% or more in total of one or two or more selected from a group consisting of ferrite, martensite and austenite by area %, in which an average block size of the above-described bainite is less than 2.0 μm, an average grain diameter of all of the above-described ferrite, martensite and austenite is less than 1.0 μm, an average nanohardness of the above-described bainite is 4.0 GPa to 5.0 GPa, and MX-type carbides each having a circle-equivalent diameter of 10 nm or more exist with an average grain spacing of 300 nm or less therebetween.
1. A steel material, comprising: by mass %,
C: greater than 0.05% to 0.18%;
Mn: 1% to 3%;
Si: greater than 0.5% to 1.8%;
Al: 0.01% to 0.5%;
N: 0.001% to 0.015%;
one or both of V and Ti: 0.01% to 0.3% in total;
Cr: 0% to 0.25%;
Mo: 0% to 0.35%;
a balance: Fe and impurities; and
80% or more of bainite by area %, and 5% or more in total of one or two or more selected from a group consisting of ferrite, martensite and austenite by area %, wherein:
an average block size of the bainite is less than 2.0 μm, and an average grain diameter of all of the ferrite, martensite and austenite is less than 1.0 μm;
an average nanohardness of the bainite is 4.0 GPa to 5.0 GPa; and
MX-type carbides each having a circle-equivalent diameter of 10 nm or more exist with an average grain spacing of 300 nm or less therebetween.
2. The steel material according to claim 1 , comprising
one or two selected from a group consisting of, by mass %,
Cr: 0.05% to 0.25%, and
Mo: 0.1% to 0.35%.
3. The steel material according to claim 1 , wherein the content of Si is 1.0% to 1.8%.
4. A steel material, consisting of, by mass %:
C: greater than 0.05% to 0.18%;
Mn: 1% to 3%;
Si: greater than 0.5% to 1.8%;
Al: 0.01% to 0.5%;
N: 0.001% to 0.015%;
one or both of V and Ti: 0.01% to 0.3% in total;
Cr: 0% to 0.25%;
Mo: 0% to 0.35%;
P: 0.02% or less;
S: 0.005% or less;
a balance: Fe and impurities; and
80% or more of bainite by area %, and 5% or more in total of one or two or more selected from the group consisting of ferrite, martensite and austenite by area %, wherein:
an average block size of the bainite is less than 2.0 μm, and an average grain diameter of all of the ferrite, martensite and austenite is less than 1.0 μm;
an average nanohardness of the bainite is 4.0 GPa to 5.0 GPa; and
MX-type carbides each having a circle-equivalent diameter of 10 nm or more exist with an average grain spacing of 300 nm or less therebetween.