JPWO2021095185A5 - - Google Patents

Claims (6)

A hot-rolled steel material having an oxide scale on at least a part of the surface of the base metal.
The chemical composition of the base material is mass%.
C: 0.01-0.10%,
Si: 0.04 to 0.40%,
Mn: 0.30 to 1.50%,
Cu: 0.02 to 0.50%,
Sb: 0.01-0.30%,
Al: 0.005 to 0.055%,
P: 0.020% or less,
S: 0.0005 to 0.015%,
N: 0.010% or less,
O: 0.0005 to 0.0035%,
Mo: 0 to 0.50%,
W: 0 to 0.50%,
Ni: 0 to 0.50%,
Sn: 0 to 0.50%,
As: 0 to 0.30%,
Co: 0 to 0.30%,
Cr: 0 to 0.70%,
Ti: 0 to 0.050%,
Nb: 0 to 0.10%,
V: 0 to 0.10%,
Zr: 0 to 0.050%,
Ta: 0 to 0.050%,
B: 0 to 0.010%,
Ca: 0 to 0.010%,
Mg: 0 to 0.010%,
REM: 0-0.010%,
Remaining: Fe and impurities,
Moreover, it satisfies 1 or more of the following conditions 1 to 3.
A concentrated layer of Si, Cu and Sb is provided at the interface between the base material and the oxide scale.
Hot rolled steel.
Conditions 1) Contains one or more selected from the group consisting of Mo: 0.01% or more, W: 0.01% or more, Sn: 0.001% or more, and As: 0.01% or more.
Condition 2) Cr: 0.01% or more, Ti: 0.001% or more, Nb: 0.001% or more, V: 0.001% or more, Zr: 0.001% or more, Ta: 0.001% or more , And B: Containing at least one selected from the group consisting of 0.0003% or more.
Condition 3) Contains one or more selected from the group consisting of Ca: 0.00005% or more, Mg: 0.0001% or more, and REM: 0.0001% or more. The chemical composition is by mass%.
Mn: 0.50 to 1.50%,
Cu: 0.05 to 0.50%,
Al: 0.005 to 0.050%,
Contains one or both of Mo and W: 0.01-0.30%,
The mass ratio Si / Al between the Si content and the Al content is 6.0 to 16.0.
The AI defined by the following equation (i) is 0.06 to 0.21.
Either the EI defined by the following equation (ii) is 2.5 to 6.0, or the total content of Cu and Sb is 0.10 to 0.25% by mass. Satisfied,
The Ceq defined by the following equation (iii) is 0.180 to 0.330.
The hot-rolled steel material according to claim 1.
AI = ((Mo / 96) + (W / 184)) / (C / 12) ... (i)
EI = (Cu / 64) / ((Sb / 122) + (Sn / 119)) ... (ii)
Ceq = C + Mn / 6 + (Cu + Ni) / 5+ (Cr + Mo + V) / 15 ... (iii)
However, the element symbol in the above formula represents the content (mass%) of each element contained in the steel material, and if it is not contained, 0 is substituted. The chemical composition is by mass%.
Sn: 0.001 to 0.50%,
The hot-rolled steel material according to claim 2. The chemical composition is by mass%.
Contains Ca: 0.00005 to 0.010%,
The XI defined by the following equation (iv) is 5.0 to 16.0.
The hot-rolled steel material according to claim 2 or 3.
XI = (Si / 28) / ((Al / 27) + (Ca / 40)) ... (iv)
However, the element symbol in the above formula represents the content (mass%) of each element contained in the steel material, and if it is not contained, 0 is substituted. The chemical composition is by mass%.
Contains Ca: 0.00005 to 0.010%,
The mass ratio Ca / O between the Ca content and the O content is 1.00 or less.
The hot-rolled steel material according to claim 2 or 3. The chemical composition is by mass%.
Cu: 0.05 to 0.50%,
Sb: 0.03 to 0.30%,
Ni: 0.01-0.50%,
Cr: 0.02 to 0.50%,
N: contains 0.002 to 0.010%,
The mass ratio of Si content to Al content is 7.0 to 15.0, and Si / Al is 7.0 to 15.0.
The BI defined by the following equation (v) is 0.55 to 30.0.
The EI defined by the following equation (ii) is 1.0 to 6.0.
Ceq defined by the following equation (iii) is 0.150 to 0.400.
The hot-rolled steel material according to claim 1.
BI = (Cr / 52) / (N / 14) ... (v)
EI = (Cu / 64) / ((Sb / 122) + (Sn / 119)) ... (ii)
Ceq = C + Mn / 6 + (Cu + Ni) / 5+ (Cr + Mo + V) / 15 ... (iii)
However, the element symbol in the above formula represents the content (mass%) of each element contained in the steel material, and if it is not contained, 0 is substituted.