# US 9,752,221 B2 · Steel sheet provided with hot dip galvanized layer excellent in plating wettability and plating adhesion and method of production of same

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- Number: US 9,752,221 B2
- Document ID: US9752221B2
- Status: Granted
- Kind: B2
- Application number: 14/346,618
- Filed: 2012-09-28
- Published: 2014-08-21
- Granted: 2017-09-05
- Earliest claimed: 2011-09-30
- Assignees: Nippon Steel & Sumitomo Metal Corporation
- Applicants: Nippon Steel & Sumitomo Metal Corporation
- Inventors: Soshi Fujita; Shintaro Yamanaka; Koichi Sato
- Web page: https://patentgrep.com/patent/US9752221B2

## CPC

- C22C 38/00: Ferrous alloys, e.g. steel alloys (cast-iron alloys C22C37/00)
- B32B 15/013: {one layer being formed of an iron alloy or steel, another layer being formed of a metal other than iron or aluminium}
- C21D 1/74: Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
- C21D 8/0278: involving a particular surface treatment (C21D8/0294 takes precedence)
- C21D 9/46: for sheet metals
- C22C 38/02: containing silicon
- C22C 38/04: containing manganese
- C22C 38/06: containing aluminium
- C22C 38/58: with more than 1.5% by weight of manganese
- C23C 2/0038: {characterised by the pre-treatment chambers located immediately upstream of the bath or occurring locally before the dipping process}
- C23C 2/02: Pretreatment of the material to be coated, e.g. for coating on selected surface areas (C23C2/30 takes precedence)
- C23C 2/0222: {in a reactive atmosphere, e.g. oxidising or reducing atmosphere (C23C2/024 takes precedence)}
- C23C 2/0224: {Two or more thermal pretreatments}
- C23C 2/024: {by cleaning or etching}
- C23C 2/06: Zinc or cadmium or alloys based thereon
- C21D 8/0226: {Hot rolling}
- C21D 8/0236: {Cold rolling}
- Y10T 428/12799: Next to Fe-base component [e.g., galvanized]
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- B32B: LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B)
- C23C: COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A steel sheet which uses steel sheet which contains the easily oxidizable elements Si and Mn as a base material and which is provided with a hot dip galvanized layer which is excellent in plating wettability and plating adhesion and a method of production of the same are provided. A hot dip galvanized steel sheet which is comprised of a steel sheet having a hot dip galvanized layer A on the surface of the steel sheet, characterized by having the following B layer right under the steel sheet surface and in the steel sheet: B layer: Layer which has thickness of 0.001 μm to 0.5 μm, which contains, based on mass of the B layer, one or more of Fe, Si, Mn, P, S, and Al oxides in a total of less than 50 mass %, which contains C, Si, Mn, P, S, and Al not in oxides in C: less than 0.05 mass %, Si: less than 0.1 mass %, Mn: less than 0.5 mass %, P: less than 0.001 mass %, S: less than 0.001 mass %, and Al: less than 0.005 mass % and which contains Fe not in oxides in 50 mass % or more.

## Claims

### Claim 1

A hot dip galvanized steel sheet comprising a steel sheet which contains, by mass %,
C: 0.05% to 0.50%,
Si: 0.1% to 3.0%,
Mn: 0.5% to 5.0%,
P: 0.001% to 0.5%,
S: 0.001% to 0.03%,
Al: 0.005% to 1.0%, and
a balance of Fe and unavoidable impurities, having a hot dip galvanized layer A on the surface of said steel sheet, characterized by having the following B layer right below said steel sheet surface and inside said steel sheet:
B layer: Layer which has thickness of 0.001 μm to 0.5 μm, which contains, based on mass of said B layer, one or more of Fe, Si, Mn, P, S, and Al oxides in a total of less than 50 mass %, which contains C, Si, Mn, P, S, and Al not in oxides in:
C: less than 0.05 mass %,
Si: less than 0.1 mass %,
Mn: less than 0.5 mass %,
P: less than 0.001 mass %,
S: less than 0.001 mass %, and
Al: less than 0.005 mass %, and
which contains Fe not in oxides in 50 mass % or more.

### Claim 2

A hot dip galvanized steel sheet comprising a steel sheet which contains, by mass %,
C: 0.05% to 0.50%,
Si: 0.1% to 3.0%,
Mn: 0.5% to 5.0%,
P: 0.001% to 0.5%,
S: 0.001% to 0.03%,
Al: 0.005% to 1.0%,
one or more elements of Ti, Nb, Cr, Mo, Ni, Cu, Zr, V, W, B, Ca, and REM in respectively 0.0001% to 1%, and
a balance of Fe and unavoidable impurities, having a hot dip galvanized layer A on the surface of said steel sheet, characterized by having the following B layer right below said steel sheet surface and inside said steel sheet:
B layer: Layer which has thickness of 0.001 μm to 0.5 μm, which contains, based on mass of said B layer, one or more of Fe, Si, Mn, P, S, Al, Ti, Nb, Cr, Mo, Ni, Cu, Zr, V, W, B, Ca, and REM oxides in a total of less than 50 mass %, which contains C, Si, Mn, P, S, Al, Ti, Nb, Cr, Mo, Ni, Cu, Zr, V, W, B, Ca, and REM not in oxides in:
C: less than 0.05 mass %,
Si: less than 0.1 mass %,
Mn: less than 0.5 mass %,
P: less than 0.001 mass %,
S: less than 0.001 mass %,
Al: less than 0.005 mass %,
one or more of Ti, Nb, Cr, Mo, Ni, Cu, Zr, V, W, B, Ca, and REM in respectively less than 0.0001 mass %, and
which contains Fe not in oxides in 50 mass % or more.

### Claim 3 (depends on 1)

The hot dip galvanized steel sheet according to claim 1, wherein said hot dip galvanized layer A has a thickness of 2 μm to 100 μm.

### Claim 4 (depends on 1)

A method of production of a hot dip galvanized steel sheet comprising casting, hot rolling, pickling, and cold rolling a steel containing the components described in claim 1 to obtain a cold rolled steel sheet, and annealing said cold rolled steel sheet and hot dip galvanizing the annealed steel sheet in a continuous hot dip galvanization facilities which are provided with a heating furnace and a soaking furnace,
wherein, in said heating furnace and said soaking furnace which perform said annealing treatment, the temperature of said cold rolled steel sheet in the furnaces being 500° C. to 950° C. in temperature range and running said cold rolled steel sheet under the following conditions:
Heating furnace conditions: Using an all radiant tube type of heating furnace, heating said cold rolled steel sheet in the above temperature range for 10 seconds to 1000 seconds, wherein the log(PH2O/PH2) of the value of the steam partial pressure (PH2O) in said heating furnace divided by the hydrogen partial pressure (PH2) is −2 to 2, and wherein said heating furnace has an atmosphere comprised of hydrogen in a hydrogen concentration of 1 vol % to 30 vol %, steam, and nitrogen;
Soaking furnace conditions: After said heating furnace, in the soaking furnace, soaking said cold rolled steel sheet in the above temperature range for 10 seconds to 1000 seconds, wherein the log(PH2O/PH2) of the value of the steam partial pressure (PH2O) in said soaking furnace divided by the hydrogen partial pressure (PH2) is −5 to less than −2, and wherein said soaking furnace has an atmosphere comprised of hydrogen in a hydrogen concentration of 1 vol % to 30 vol %, steam, and nitrogen.

### Claim 5 (depends on 2)

The hot dip galvanized steel sheet according to claim 2, wherein said hot dip galvanized layer A has a thickness of 2 μm to 100 μm.

### Claim 6 (depends on 2)

A method of production of a hot dip galvanized steel sheet comprising casting, hot rolling, pickling, and cold rolling a steel containing the components described in claim 2 to obtain a cold rolled steel sheet, and annealing said cold rolled steel sheet and hot dip galvanizing the annealed steel sheet in a continuous hot dip galvanization facilities which are provided with a heating furnace and a soaking furnace,
wherein, in said heating furnace and said soaking furnace which perform said annealing treatment, the temperature of said cold rolled steel sheet in the furnaces being 500° C. to 950° C. in temperature range and running said cold rolled steel sheet under the following conditions:
Heating furnace conditions: Using an all radiant tube type of heating furnace, heating said cold rolled steel sheet in the above temperature range for 10 seconds to 1000 seconds, wherein the log(PH2O/PH2) of the value of the steam partial pressure (PH2O) in said heating furnace divided by the hydrogen partial pressure (PH2) is −2 to 2, and wherein said heating furnace has an atmosphere comprised of hydrogen in a hydrogen concentration of 1 vol % to 30 vol %, steam, and nitrogen;
Soaking furnace conditions: After said heating furnace, in the soaking furnace, soaking said cold rolled steel sheet in the above temperature range for 10 seconds to 1000 seconds, wherein the log(PH2O/PH2) of the value of the steam partial pressure (PH2O) in said soaking furnace divided by the hydrogen partial pressure (PH2) is −5 to less than −2, and wherein said soaking furnace has an atmosphere comprised of hydrogen in a hydrogen concentration of 1 vol % to 30 vol %, steam, and nitrogen.

### Claim 7

A hot dip galvannealed steel sheet comprising a steel sheet which contains, by mass %,
C: 0.05% to 0.50%,
Si: 0.1% to 3.0%,
Mn: 0.5% to 5.0%,
P: 0.001% to 0.5%,
S: 0.001% to 0.03%,
Al: 0.005% to 1.0%, and
a balance of Fe and unavoidable impurities, having a hot dip galvannealed layer A on the surface of said steel sheet, characterized by having the following B layer right below said steel sheet surface and inside said steel sheet:
B layer: Layer which has thickness of 0.001 μm to 0.5 μm, which contains, based on mass of said B layer, one or more of Fe, Si, Mn, P, S, and Al oxides in a total of less than 50 mass %, which contains C, Si, Mn, P, S, and Al not in oxides in:
S, and Al not in oxides in:
C: less than 0.05mass %,
Si: less than 0.1 mass %,
Mn: less than 0.5 mass %,
P: less than 0.001 mass %,
S: less than 0.001 mass %, and
Al: less than 0.005 mass %, and
which contains Fe not in oxides in 50 mass % or more.

### Claim 8

A hot dip galvannealed steel sheet comprising a steel sheet which contains, by mass %,
C: 0.05% to 0.50%,
Si: 0.1% to 3.0%,
Mn: 0.5% to 5.0%,
P: 0.001% to 0.5%,
S: 0.001% to 0.03%,
Al: 0.005% to 1.0%,
one or more elements of Ti, Nb, Cr, Mo, Ni, Cu, Zr, V, W, B, Ca, and REM in respectively 0.0001% to 1%, and
a balance of Fe and unavoidable impurities, having a hot dip galvannealed layer A on the surface of said steel sheet, characterized by having the following B layer right below said steel sheet surface and inside said steel sheet:
B layer: Layer which has thickness of 0.001 μm to 0.5 μm, which contains, based on mass of said B layer, one or more of Fe, Si, Mn, P, S, Al, Ti, Nb, Cr, Mo, Ni, Cu, Zr, V, W, B, Ca, and REM oxides in a total of less than 50 mass %, which contains C, Si, Mn, P, S, Al, Ti, Nb, Cr, Mo, Ni, Cu, Zr, V, W, B, Ca, and REM not in oxides in:
C: less than 0.05 mass %,
Si: less than 0.1 mass %,
Mn: less than 0.5 mass %,
P: less than 0.001 mass %,
S: less than 0.001 mass %,
Al: less than 0.005 mass %,
one or more of Ti, Nb, Cr, Mo, Ni, Cu, Zr, V, W, B, Ca, and REM in respectively less than 0.0001 mass %, and
which contains Fe not in oxides in 50 mass % or more.

### Claim 9 (depends on 7)

The hot dip galvannealed steel sheet according to claim 7, wherein said hot dip galvannealed layer A has a thickness of 2 μm to 100 μm.

### Claim 10 (depends on 8)

The hot dip galvannealed steel sheet according to claim 8, wherein said hot dip galvannealed layer A has a thickness of 2 μm to 100 μM.

### Claim 11 (depends on 7)

A method of production of a hot dip galvannealed steel sheet comprising casting, hot rolling, pickling, and cold rolling a steel containing the components described in claim 7 to obtain a cold rolled steel sheet, and annealing said cold rolled steel sheet and hot dip galvanizing the annealed steel sheet in a continuous hot dip galvanization facilities which are provided with a heating furnace and a soaking furnace, and alloying the hot dip galvanized steel sheet,
wherein, in said heating furnace and said soaking furnace which perform said annealing treatment, the temperature of said cold rolled steel sheet in the furnaces being 500° C. to 950° C. in temperature range and running said cold rolled steel sheet under the following conditions:
Heating furnace conditions: Using an all radiant tube type of heating furnace, heating said cold rolled steel sheet in the above temperature range for 10 seconds to 1000 seconds, wherein the log(PH2O/PH2) of the value of the steam partial pressure (PH2O) in said heating furnace divided by the hydrogen partial pressure (PH2) is −2 to 2, and wherein said heating furnace has an atmosphere comprised of hydrogen in a hydrogen concentration of 1 vol % to 30 vol %, steam, and nitrogen;
Soaking furnace conditions: After said heating furnace, in the soaking furnace, soaking said cold rolled steel sheet in the above temperature range for 10 seconds to 1000 seconds, wherein the log(PH2O/PH2) of the value of the steam partial pressure (PH2O) in said soaking furnace divided by the hydrogen partial pressure (PH2) is −5 to less than −2, and wherein said soaking furnace has an atmosphere comprised of hydrogen in a hydrogen concentration of 1 vol % to 30 vol %, steam, and nitrogen.

### Claim 12 (depends on 8)

A method of production of a hot dip galvannealed steel sheet comprising casting, hot rolling, pickling, and cold rolling a steel containing the components described in claim 8 to obtain a cold rolled steel sheet, and annealing said cold rolled steel sheet and hot dip galvanizing the annealed steel sheet in a continuous hot dip galvanization facilities which are provided with a heating furnace and a soaking furnace, and alloying the hot dip galvanized steel sheet,
wherein, in said heating furnace and said soaking furnace which perform said annealing treatment, the temperature of said cold rolled steel sheet in the furnaces being 500° C. to 950° C. in temperature range and running said cold rolled steel sheet under the following conditions:
Heating furnace conditions: Using an all radiant tube type of heating furnace, heating said cold rolled steel sheet in the above temperature range for 10 seconds to 1000 seconds, wherein the log(PH2O/PH2) of the value of the steam partial pressure (PH2O) in said heating furnace divided by the hydrogen partial pressure (PH2) is −2 to 2, and wherein said heating furnace has an atmosphere comprised of hydrogen in a hydrogen concentration of 1 vol % to 30 vol %, steam, and nitrogen;
Soaking furnace conditions: After said heating furnace, in the soaking furnace, soaking said cold rolled steel sheet in the above temperature range for 10 seconds to 1000 seconds, wherein the log(PH2O/PH2) of the value of the steam partial pressure (PH2O) in said soaking furnace divided by the hydrogen partial pressure (PH2) is −5 to less than −2, and wherein said soaking furnace has an atmosphere comprised of hydrogen in a hydrogen concentration of 1 vol % to 30 vol %, steam, and nitrogen.