US 2008/0075971 A1 · High strength, hot dip coated, dual phase, steel sheet and method of manufacturing same

A galvanized steel sheet comprising:

(a) a dual phase microstructure comprising a martensite phase and a ferrite phase;
(b) a composition comprising:
carbon in a range from about 0.01% by weight to about 0.18% by weight,
manganese in a range from about 0.2% by weight to about 3% by weight,
silicon ≦ about 1.2% by weight,
aluminum in a range from about 0.01% by weight to about 0.1% by weight,
chromium or nickel or a combination thereof in a range from about 0.1% by weight to about 3.5% by weight,
calcium in a range from about 0.0003% by weight to about 0.01% by weight,
phosphorus ≦ about 0.01% by weight,
sulfur ≦ about 0.03% by weight,
nitrogen ≦ about 0.02% by weight,
molybdenum ≦ about 1% by weight,
copper ≦ about 0.8% by weight,
niobium or titanium or vanadium or a combination thereof ≦ about 1% by weight, and
boron ≦ about 0.006% by weight, and
with the balance of the composition comprising iron and incidental ingredients;
and
(c) one or more of a property chosen from (i) a weldability superior to that of known galvanized steel sheet having a dual phase microstructure of a martensite phase and a ferrite phase, (ii) an impact energy ≧ about 1200 g-m, measured on a V-notch Charpy specimen of about 1.5 mm thickness, or (iii) a yield strength/tensile strength ratio ≦ about 70%.

15 more elements

A galvanized steel sheet comprising:

(a) a dual phase microstructure comprising a martensite phase and a ferrite phase;
(b) a composition comprising:
carbon in a range from about 0.01% by weight to about 0.18% by weight,
manganese in a range from about 0.2% by weight to about 3% by weight,
silicon ≦ about 1.2% by weight,
aluminum in a range from about 0.01% by weight to about 0.1% by weight,
chromium or nickel or a combination thereof in a range from about 0.1% by weight to about 3.5% by weight,
calcium in a range from about 0.0003% by weight to about 0.01% by weight,
phosphorus ≦ about 0.01% by weight,
sulfur ≦ about 0.03% by weight,
nitrogen ≦ about 0.02% by weight,
molybdenum ≦ about 1% by weight,
copper ≦ about 0.8% by weight,
niobium or titanium or vanadium or a combination thereof ≦ about 1% by weight, and
boron ≦ about 0.006% by weight, and
with the balance of the composition comprising iron and incidental ingredients;
and
(c) one or more of a property chosen from (i) a weldability superior to that of known galvanized steel sheet having a dual phase microstructure of a martensite phase and a ferrite phase, (ii) an impact energy ≧ about 1200 g-m, measured on a V-notch Charpy specimen of about 1.5 mm thickness, or (iii) a yield strength/tensile strength ratio ≦ about 70%;
and
wherein the steel sheet is made by a method comprising:
(I) at a temperature in a range between about (Ar3-60)° C. and about 980° C. (about 1796° F.), hot rolling a steel slab having said composition into a hot band;
(II) cooling the hot band at a mean rate of at least about 3° C./s (about 5.4° F./s) to a temperature not higher than about 800° C. (about 1472° F.);
(III) coiling the cooled band to form a coil of the steel sheet;
and
(IV) galvanizing the steel sheet by heating to a temperature higher than about 600° C. (about 1112° F.), holding the temperature in a soaking zone of a galvanizing line while using a line speed or process speed faster than about 30 m/min, cooling the steel sheet to a temperature close to the temperature in the galvanizing bath in a range between about 400° C. (about 752° F.) and about 550° C. (about 1022° F.), passing the steel sheet through the galvanizing bath to coat the steel sheet with a zinc coating or a zinc alloy coating, and cooling the galvanized steel sheet.

22 more elements

A galvanized steel sheet comprising:

(a) a dual phase microstructure comprising a martensite phase and a ferrite phase, wherein the martensite phase comprises from about 3% by volume to about 35% by volume of the microstructure;
(b) a composition comprising:
carbon in a range from about 0.02% by weight to about 0.12% by weight,
manganese in a range from about 0.3% by weight to about 2.8% by weight,
silicon ≦ about 1% by weight,
aluminum in a range from about 0.015% by weight to about 0.09% by weight,
chromium or nickel or a combination thereof in a range from about 0.2% by weight to about 3% by weight,
calcium in a range from about 0.0005% by weight to about 0.009% by weight,
phosphorus ≦ about 0.08% by weight,
sulfur ≦ about 0.02% by weight,
nitrogen ≦ about 0.015% by weight,
molybdenum ≦ about 0.8% by weight,
copper ≦ about 0.6% by weight,
niobium or titanium or vanadium or a combination thereof ≦ about 0.8% by weight, and
boron ≦ about 0.003% by weight, and
with the balance of the composition comprising iron and incidental ingredients;
and
(c) properties of (i) a weldability superior to that of known galvanized steel sheet having a dual phase microstructure of a martensite phase and a ferrite phase, (ii) a yield strength/tensile strength ratio ≦ about 70%, (iii) an impact energy ≧ about 1200 g-m, measured on a V-notch Charpy specimen of about 1.5 mm thickness, (iv) an elongation ≧ about 20%, and (v) an excellent n-value;
and
wherein the steel sheet is made by a method comprising:
(I) at a temperature in a range between about (Ar3-30)° C. and about 930° C. (about 1706° F.), hot rolling a steel slab having said composition into a hot band;
(II) cooling the hot band at a mean rate of at least about 5° C./s (about 9° F./s);
(III) coiling the cooled band at a temperature in a range between 400° C. (about 752° F.) and about 750° C. (about 1382° F.) to form a coil of the steel sheet;
(IV) pickling the coil;
(V) cold rolling the pickled coil to a desired steel sheet thickness, with a total reduction of at least about 30%;
and
(VI) galvanizing the steel sheet by heating to a temperature in a range between about 650° C. (1202° F.) and about 950° C. (about 1742° F.), holding the temperature in a soaking zone of a galvanizing line while using a line speed or process speed in a range from about 50 m/min to about 150 m/min, and cooling the steel sheet to a temperature close to the temperature in the galvanizing bath in a range between about 425° C. (about 797° F.) and about 500° C. (about 932° F.), passing the steel sheet through the galvanizing bath to coat the steel sheet with a zinc coating or a zinc alloy coating, and cooling the galvanized steel sheet.

24 more elements

A method of making a galvanized steel sheet, comprising:

(I) at a temperature in a range between about (Ar3-60)° C. and about 980° C. (about 1796° F.), hot rolling a steel slab into a hot band, wherein the steel slab comprises a composition comprising:
carbon in a range from about 0.01% by weight to about 0.18% by weight,
manganese in a range from about 0.2% by weight to about 3% by weight,
silicon ≦ about 1.2% by weight,
aluminum in a range from about 0.01% by weight to about 0.1% by weight,
chromium or nickel or a combination thereof in a range from about 0.1% by weight to about 3.5% by weight,
calcium in a range from about 0.0003% by weight to about 0.01% by weight,
phosphorus ≦ about 0.01% by weight,
sulfur ≦ about 0.03% by weight,
nitrogen ≦ about 0.02% by weight,
molybdenum ≦ about 1% by weight,
copper ≦ about 0.8% by weight,
niobium or titanium or vanadium or a combination thereof ≦ about 1% by weight, and
boron ≦ about 0.006% by weight, and
with the balance of said composition comprising iron and incidental ingredients;
(II) cooling the hot band at a mean rate of at least about 3° C./s (about 5.4° F./s) to a temperature not higher than about 800° C. (about 1472° F.);
(III) coiling the cooled band to form a coil;
(IV) galvanizing the steel sheet by heating to a temperature higher than about 600° C. (1112° F.), holding the temperature in a soaking zone of a galvanizing line while using a line speed or process speed faster than about 30 m/min, cooling the steel sheet to a temperature close to the temperature in the galvanizing bath in a range between about 400° C. (about 752° F.) and about 550° C. (about 1022° F.), passing the steel sheet through the galvanizing bath to coat the steel sheet with a zinc coating or a zinc alloy coating, and cooling the galvanized steel sheet;
and
(V) obtaining a galvanized steel sheet comprising (a) a dual phase microstructure comprising a martensite phase and a ferrite phase, (b) said composition, and (c) one or more of a property chosen from (i) a weldability superior to that of known galvanized steel sheet having a dual phase microstructure of a martensite phase and a ferrite phase, (ii) an impact energy ≧ about 1200 g-m, measured on a V-notch Charpy specimen of about 1.5 mm thickness, or (iii) a yield strength/tensile strength ratio ≦ about 70%.

17 more elements

A method of making a galvanized steel sheet, comprising:

(I) at a temperature in a range between about (Ar3-30)° C. and about 930° C. (about 1706° F.), hot rolling a steel slab having said composition into a hot band, wherein the steel slab comprises a composition comprising:
carbon in a range from about 0.02% by weight to about 0.12% by weight,
manganese in a range from about 0.3% by weight to about 2.8% by weight,
silicon ≦ about 1% by weight,
aluminum in a range from about 0.015% by weight to about 0.09% by weight,
chromium or nickel or a combination thereof in a range from about 0.2% by weight to about 3% by weight,
calcium in a range from about 0.0005% by weight to about 0.009% by weight,
phosphorus ≦ about 0.08% by weight,
sulfur ≦ about 0.02% by weight,
nitrogen ≦ about 0.015% by weight,
molybdenum ≦ about 0.8% by weight,
copper ≦ about 0.6% by weight,
niobium or titanium or vanadium or a combination thereof ≦ about 0.8% by weight, and
boron ≦ about 0.003% by weight, and
with the balance of the composition comprising iron and incidental ingredients;
(II) cooling the hot band at a mean rate of at least about 5° C./s (about 9° F./s);
(III) coiling the cooled band at a temperature in a range between 400° C. (about 752° F.) and about 750° C. (about 1382° F.) to form a coil of the steel sheet;
(IV) pickling the coil;
(V) cold rolling the pickled coil to a desired steel sheet thickness, with a total reduction of at least about 30%;
(VI) galvanizing the steel sheet by heating to a temperature in a range between about 650° C. (1202° F.) and about 950° C. (about 1742° F.), holding the temperature in a soaking zone of a galvanizing line while using a line speed or process speed in a range from about 50 m/min to about 150 m/min, and cooling the steel sheet to a temperature close to the temperature in the galvanizing bath in a range between about 425° C. (about 797° F.) and about 500° C. (about 932° F.), passing the steel sheet through the galvanizing bath to coat the steel sheet with a zinc coating or a zinc alloy coating, and cooling the galvanized steel sheet;
and
(VII) obtaining a galvanized steel sheet comprising (a) a dual phase microstructure comprising a martensite phase and a ferrite phase, wherein the martensite phase comprises from about 3% by volume to about 35% by volume of the microstructure (b) said composition, and (c) properties of (i) a weldability superior to that of known galvanized steel sheet having a dual phase microstructure of a martensite phase and a ferrite phase, (ii) a yield strength/tensile strength ratio ≦ about 70%, (iii) an impact energy ≧ about 1200 g-m, measured on a V-notch Charpy specimen of about 1.5 mm thickness, (iv) an elongation ≧ about 20%, and (vii) an excellent n-value.

19 more elements

A galvanized and galvannealed steel sheet comprising:

(a) a dual phase microstructure comprising a martensite phase and a ferrite phase, wherein the martensite phase comprises from about 3% by volume to about 35% by volume of the microstructure;
(b) a composition comprising:
carbon in a range from about 0.01% by weight to about 0.18% by weight,
manganese in a range from about 0.2% by weight to about 3% by weight,
silicon ≦ about 1.2% by weight,
aluminum in a range from about 0.01% by weight to about 0.1% by weight,
chromium or nickel or a combination thereof in a range from about 0.1% by weight to about 3.5% by weight,
calcium in a range from about 0.0003% by weight to about 0.01% by weight,
phosphorus ≦ about 0.01% by weight,
sulfur ≦ about 0.03% by weight,
nitrogen ≦ about 0.02% by weight,
molybdenum ≦ about 1% by weight,
copper ≦ about 0.8% by weight,
niobium or titanium or vanadium or a combination thereof ≦ about 1% by weight, and
boron ≦ about 0.006% by weight, and
with the balance of the composition comprising iron and incidental ingredients;
and
(c) one or more of a property chosen from (i) a weldability superior to that of known galvanized and galvannealed steel sheet having a dual phase microstructure of a martensite phase and a ferrite phase, (ii) an impact energy ≧ about 1200 g-m, measured on a V-notch Charpy specimen of about 1.5 mm thickness, or (iii) a yield strength/tensile strength ratio ≦ about 70%.

15 more elements

A galvanized and galvannealed steel sheet comprising:

(a) a dual phase microstructure comprising a martensite phase and a ferrite phase, wherein the martensite phase comprises from about 3% by volume to about 35% by volume of the microstructure;
(b) a composition comprising:
carbon in a range from about 0.01% by weight to about 0.18% by weight,
manganese in a range from about 0.2% by weight to about 3% by weight,
silicon ≦ about 1.2% by weight,
aluminum in a range from about 0.01% by weight to about 0.1% by weight,
chromium or nickel or a combination thereof in a range from about 0.1% by weight to about 3.5% by weight,
calcium in a range from about 0.0003% by weight to about 0.01% by weight,
phosphorus ≦ about 0.01% by weight,
sulfur ≦ about 0.03% by weight,
nitrogen ≦ about 0.02% by weight,
molybdenum ≦ about 1% by weight,
copper ≦ about 0.8% by weight,
niobium or titanium or vanadium or a combination thereof ≦ about 1% by weight, and
boron ≦ about 0.006% by weight, and
with the balance of the composition comprising iron and incidental ingredients;
and
(c) one or more of a property chosen from (i) a weldability superior to that of known galvanized and galvannealed steel sheet having a dual phase microstructure of a martensite phase and a ferrite phase, (ii) an impact energy ≧ about 1200 g-m, measured on a V-notch Charpy specimen of about 1.5 mm thickness, or (iii) a yield strength/tensile strength ratio ≦ about 70%;
and
wherein the galvanized and galvannealed steel sheet is made by a method comprising:
(I) at a temperature in a range between about (Ar3-60)° C. and about 980° C. (about 1796° F.), hot rolling a steel slab having said composition into a hot band;
(II) cooling the hot band at a mean rate of at least about 3° C./s (about 5.4° F./s) to a temperature not higher than about 800° C. (about 1472° F.);
(III) coiling the cooled band to form a coil;
(IV) galvanizing the steel sheet by heating to a temperature higher than 600° C. (1112° F.), holding the temperature in a soaking zone of a galvanizing line while using a line speed or process speed faster than about 30 m/min, cooling the steel sheet to a temperature close to the temperature in the galvanizing bath in a range between about 400° C. (about 752° F.) and about 550° C. (about 1022° F.), passing the steel sheet through the galvanizing bath to coat the steel sheet with a zinc coating or a zinc alloy coating, and cooling the galvanized steel sheet;
and
(V) galvannealing the steel sheet by reheating to a temperature in a range from about 450° C. (about 842° F.) to about 650° C. (about 1202° F.) and cooling the steel sheet.

23 more elements

A galvanized and galvannealed steel sheet comprising:

(a) a dual phase microstructure comprising a martensite phase and a ferrite phase, wherein the martensite phase comprises from about 3% by volume to about 35% by volume of the microstructure;
(b) a composition comprising:
carbon in a range from about 0.02% by weight to about 0.12% by weight,
manganese in a range from about 0.3% by weight to about 2.8% by weight,
silicon ≦ about 1% by weight,
aluminum in a range from about 0.015% by weight to about 0.09% by weight,
chromium or nickel or a combination thereof in a range from about 0.2% by weight to about 3% by weight,
calcium in a range from about 0.0005% by weight to about 0.009% by weight,
phosphorus ≦ about 0.08% by weight,
sulfur ≦ about 0.02% by weight,
nitrogen ≦ about 0.015% by weight,
molybdenum ≦ about 0.8% by weight,
copper ≦ about 0.6% by weight,
niobium or titanium or vanadium or a combination thereof ≦ about 0.8% by weight, and
boron ≦ about 0.003% by weight, and
with the balance of the composition comprising iron and incidental ingredients;
and
(c) properties of (i) a weldability superior to that of known galvanized and galvannealed steel sheet having a dual phase microstructure of a martensite phase and a ferrite phase, (ii) a yield strength/tensile strength ratio ≦ about 70%, (iii) an impact energy ≧ about 1200 g-m, measured on a V-notch Charpy specimen of about 1.5 mm thickness, (iv) an elongation ≧ about 20%, and (v) an excellent n-value;
and
wherein the steel sheet is made by a method comprising:
(I) at a temperature in a range between about (Ar3-30)° C. and about 930° C. (about 1706° F.), hot rolling a steel slab having said composition into a hot band;
(II) cooling the hot band at a mean rate of at least about 5° C./s (about 9° F./s);
(III) coiling the cooled band at a temperature in a range between 400° C. (about 752° F.) and about 750° C. (about 1382° F.) to form a coil of the steel sheet;
(IV) pickling the coil;
(V) cold rolling the pickled coil to a desired steel sheet thickness, with a total reduction of at least about 30%;
(VI) galvanizing the steel sheet by heating to a temperature in a range between about 650° C. (1202° F.) and about 950° C. (about 1742° F.), holding the temperature in a soaking zone of a galvanizing line while using a line speed or process speed in a range from about 50 m/min to about 150 m/min, and cooling the steel sheet to a temperature close to the temperature in the galvanizing bath in a range between about 425° C. (about 797° F.) and about 500° C. (about 932° F.), passing the steel sheet through the galvanizing bath to coat the steel sheet with a zinc coating or a zinc alloy coating, and cooling the galvanized steel sheet;
and
(VII) galvannealing the steel sheet by reheating to a temperature in a range from about 500° C. (about 932° F.) to about 600° C. (about 1112° F.) and cooling the steel sheet.

25 more elements

A method of making a galvanized and galvannealed steel sheet, comprising:

(I) at a temperature in a range between about (Ar3-60)° C. and about 980° C. (about 1796° F.), hot rolling a steel slab into a hot band, wherein the steel slab comprises a composition comprising:
carbon in a range from about 0.01% by weight to about 0.18% by weight,
manganese in a range from about 0.2% by weight to about 3% by weight,
silicon ≦ about 1.2% by weight,
aluminum in a range from about 0.01% by weight to about 0.1% by weight,
chromium or nickel or a combination thereof in a range from about 0.1% by weight to about 3.5% by weight,
calcium in a range from about 0.0003% by weight to about 0.01% by weight,
phosphorus ≦ about 0.01% by weight,
sulfur ≦ about 0.03% by weight,
nitrogen ≦ about 0.02% by weight,
molybdenum ≦ about 1% by weight,
copper ≦ about 0.8% by weight,
niobium or titanium or vanadium or a combination thereof ≦ about 1% by weight, and
boron ≦ about 0.006% by weight, and
with the balance of said composition comprising iron and incidental ingredients;
(II) cooling the hot band at a mean rate of at least about 3° C./s (about 5.4° F./s) to a temperature not higher than about 800° C. (about 1472° F.);
(III) coiling the cooled band to form a coil;
(IV) galvanizing the steel sheet by heating to a temperature higher than about 600° C. (about 1112° F.), holding the temperature in a soaking zone of a galvanizing line while using a line speed or process speed faster than about 30 m/min, cooling the steel sheet to a temperature close to the temperature in the galvanizing bath in a range between about 400° C. (about 752° F.) and about 550° C. (about 1022° F.), passing the steel sheet through the galvanizing bath to coat the steel sheet with a zinc coating or a zinc alloy coating, and cooling the galvanized steel sheet;
(V) galvannealing the steel sheet by reheating to a temperature in a range from about 450° C. (about 842° F.) to about 650° C. (about 1202° F.) and cooling the steel sheet;
and
(VI) obtaining a galvanized and galvannealed steel sheet comprising (a) a dual phase microstructure comprising a martensite phase and a ferrite phase, wherein the martensite phase comprises from about 3% by volume to about 35% by volume of the microstructure, (b) said composition, and (c) one or more of a property chosen from (i) a weldability superior to that of known galvanized and galvannealed steel sheet having a dual phase microstructure of a martensite phase and a ferrite phase, (ii) an impact energy ≧ about 1200 g-m, measured on a V-notch Charpy specimen of about 1.5 mm thickness, or (iii) a yield strength/tensile strength ratio ≦ about 70%.

18 more elements

A method of making a galvanized and galvannealed steel sheet, comprising:

(I) at a temperature in a range between about (Ar3-30)° C. and about 930° C. (about 1706° F.), hot rolling a steel slab having said composition into a hot band, wherein the steel slab comprises a composition comprising:
carbon in a range from about 0.02% by weight to about 0.12% by weight,
manganese in a range from about 0.3% by weight to about 2.8% by weight,
silicon ≦ about 1% by weight,
aluminum in a range from about 0.0015% by weight to about 0.09% by weight,
chromium or nickel or a combination thereof in a range from about 0.2% by weight to about 3% by weight,
calcium in a range from about 0.0005% by weight to about 0.009% by weight,
phosphorus ≦ about 0.08% by weight,
sulfur ≦ about 0.02% by weight,
nitrogen ≦ about 0.015% by weight,
molybdenum ≦ about 0.8% by weight,
copper ≦ about 0.6% by weight,
niobium or titanium or vanadium or a combination thereof ≦ about 0.8% by weight, and
boron ≦ about 0.003% by weight, and
with the balance of the composition comprising iron and incidental ingredients;
(II) cooling the hot band at a mean rate of at least about 5° C./s (about 9° F./s);
(III) coiling the cooled band at a temperature in a range between 400° C. (about 752° F.) and about 750° C. (about 1382° F.) to form a coil of the steel sheet;
(IV) pickling the coil;
(V) cold rolling the pickled coil to a desired steel sheet thickness, with a total reduction of at least about 30%;
(VI) galvanizing the steel sheet by heating to a temperature in a range between about 650° C. (1202° F.) and about 950° C. (about 1742° F.), holding the temperature in a soaking zone of a galvanizing line while using a line speed or process speed in a range from about 50 m/min to about 150 m/min, and cooling the steel sheet to a temperature close to the temperature in the galvanizing bath in a range between about 425° C. (about 797° F.) and about 500° C. (about 932° F.), passing the steel sheet through the galvanizing bath to coat the steel sheet with a zinc coating or a zinc alloy coating, and cooling the galvanized steel sheet;
(VII) galvannealing the steel sheet by reheating to a temperature in a range from about 500° C. (about 932° F.) to about 600° C. (about 1112° F.) and cooling the steel sheet;
and
(VIII) obtaining a galvanized and galvannealed steel sheet comprising (a) a dual phase microstructure comprising a martensite phase and a ferrite phase, wherein the martensite phase comprises from about 3% by volume to about 35% by volume of the microstructure (b) said composition, and (c) properties of (i) a weldability superior to that of known galvanized steel sheet having a dual phase microstructure of a martensite phase and a ferrite phase, (ii) a yield strength/tensile strength ratio ≦ about 70%, (iii) an impact energy ≧ about 1200 g-m, measured on a V-notch Charpy specimen of about 1.5 mm thickness, (iv) an elongation ≧ about 20%, and (vii) an excellent n-value.

20 more elements

High strength, hot dip coated, dual phase, steel sheet and method of manufacturing same

Life of this patent

High strength, hot dip coated, dual phase, steel sheet and method of manufacturing same

Life of this patent

Abstract

Claims46