Coated steel member, coated steel sheet, and methods for producing same
AssigneeNippon Steel Corporation
InventorShinichiro Tabata
Life of this patent
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Abstract
A coated steel member includes: a steel sheet substrate containing, as a chemical composition, by mass %, C: 0.25% to 0.65%, Si: 0.10% to 1.00%, Mn: 0.30% to 1.00%, P: 0.050% or less, S: 0.0100% or less, N: 0.010% or less, Ti: 0.010% to 0.100%, B: 0.0005% to 0.0100%, Nb: 0.02% to 0.10%, Mo: 0.10% to 1.00%, Cu: 0.15% to 1.00%, and Ni: 0.05% to 0.25%; and a coating formed on a surface of the steel sheet substrate and containing Al and Fe. The maximum Cu content in a range from the surface to a depth of 5.0 μm is 150% or more of the Cu content of the steel sheet substrate.
Claims3
A coated steel sheet comprising:
- a steel sheet containing, as a chemical composition, by mass %,
- C:
- 0.25% to 0.65%,
- Si:
- 0.10% to 1.00%,
- Mn:
- 0.30% to 1.00%,
- P:
- 0.050% or less,
- S:
- 0.0100% or less,
- N:
- 0.010% or less,
- Ti:
- 0.010% to 0.100%,
- B:
- 0.0005% to 0.0100%,
- Nb:
- 0.02% to 0.10%,
- Mo:
- 0.10% to 1.00%,
- Cu:
- 0.15% to 1.00%,
- Ni:
- 0.05% to 0.25%,
- Cr:
- 0% to 1.00%,
- V:
- 0% to 1.00%,
- Ca:
- 0% to 0.010%,
- Al:
- 0% to 1.00%,
- Sn:
- 0% to 1.00%,
- W:
- 0% to 1.00%,
- Sb:
- 0% to 1.00%,
- Zr:
- 0% to 1.00%,
- REM:
- 0% to 0.30%, and
- a remainder consisting of Fe and impurities;
- a coating on a surface of the steel sheet and containing Al;
- and
- a boundary portion formed between the steel sheet and the coating,
- wherein a maximum Cu content of the boundary portion is 80% or more of an average Cu content of the steel sheet.
A method for producing a coated steel sheet, the method comprising:
- melting and casting a steel containing, as a chemical composition, by mass %, C:
- 0.25% to 0.65%, Si:
- 0.10% to 1.00%, Mn:
- 0.30% to 1.00%, P:
- 0.050% or less, S:
- 0.0100% or less, N:
- 0.010% or less, Ti:
- 0.010% to 0.100%, B:
- 0.0005% to 0.0100%, Nb:
- 0.02% to 0.10%, Mo:
- 0.10% to 1.00%, Cu:
- 0.15% to 1.00%, Ni:
- 0.05% to 0.25%, Cr:
- 0% to 1.00%, V:
- 0% to 1.00%, Ca:
- 0% to 0.010%, Al:
- 0% to 1.00%, Sn:
- 0% to 1.00%, W:
- 0% to 1.00%, Sb:
- 0% to 1.00%, Zr:
- 0% to 1.00%, REM:
- 0% to 0.30%, and a remainder consisting of Fe and impurities, to obtain a slab;
- hot-rolling the slab into a hot-rolled steel sheet;
- coiling the hot-rolled steel sheet;
- as necessary, annealing the hot-rolled steel sheet;
- as necessary, descaling the hot-rolled steel sheet and cold-rolling the hot-rolled steel sheet into a cold-rolled steel sheet;
- as necessary, annealing the hot-rolled steel sheet or the cold-rolled steel sheet into an annealed steel sheet;
- and
- forming an Al-based coating by immersing the hot-rolled steel sheet, the cold-rolled steel sheet, or the annealed steel sheet in an Al-based plating bath having a bath temperature of 600° C. or higher, and then cooling the hot-rolled steel sheet, the cold-rolled steel sheet, or the annealed steel sheet to 200° C. or lower at an average cooling rate of slower than 30° C./s.
Dependencies are inferred from the claim text.