US2025277283A1PendingUtilityA1
Hot rolled and steel sheet and a method of manufacturing thereof
Est. expiryMay 13, 2042(~15.8 yrs left)· nominal 20-yr term from priority
C21D 8/02C22C 38/14C22C 38/12C22C 38/06C22C 38/04C22C 38/02C21D 8/0247C21D 8/0242C21D 8/0226C21D 2211/001C21D 2211/008C21D 2211/005C21D 2211/002C21D 9/46C21D 6/005C21D 8/0263C22C 38/004C22C 38/001C21D 1/18C21D 8/0205
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Claims
Abstract
A hot rolled steel sheet having a composition including of the following elements 0.060%≤Carbon≤0.1%, 1.4%≤Manganese≤1.8%, 0.3%≤Silicon≤0.8%, 0.01%≤Aluminum≤0.1%, 0.01%≤Niobium≤0.09%, 0.01%≤Titanium≤0.09%, 0.002%≤Phosphorus≤0.02%, 0%≤Sulfur≤0.005%, 0%≤Nitrogen≤0.01%, with 0.045%≤Ti+Nb≤0.060%, 0%≤Chromium≤0.5%, 0%≤Molybdenum≤0.4%, 0%≤Vanadium≤0.4%, 0%≤Calcium≤0.005%, 0%≤Copper≤1%, 0%≤Nickel≤1%, 0%≤Boron≤0.05%, 0%≤Magnesium≤0.05%, the remainder composition being composed of iron and unavoidable impurities caused by processing, the microstructure of the steel sheet including in area fraction, 10% to 20% Bainite, 80% to 92% Ferrite wherein the aspect ratio of the grains of Bainite and Ferrite is less than 1.75 and a cumulated amount of Residual Austenite and Martensite is from 0% to 10%.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1 - 15 . (canceled)
16 . A hot rolled steel sheet having a composition comprising of the following elements, expressed in percentage by weight:
0.06
%
≤
Carbon
≤
0.1
%
;
1.4
%
≤
Manganese
≤
1.8
%
;
0.3
%
≤
Silicon
≤
0.8
%
;
0.01
%
≤
Aluminum
≤
0.1
%
;
0.01
%
≤
Niobium
≤
0.09
%
;
0.01
%
≤
Titanium
≤
0.09
%
;
0.002
%
≤
Phosphorus
≤
0.02
%
;
0
%
≤
Sulfur
≤
0.005
%
;
0
%
≤
Nitrogen
≤
0.01
%
;
with
0.045
%
≤
Ti
+
Nb
≤
0.06
%
;
and one or more of the following optional elements:
0
%
≤
Chromium
≤
0.5
%
;
0
%
≤
Molybdenum
≤
0.4
%
;
0
%
≤
Vanadium
≤
0.4
%
;
0
%
≤
Calcium
≤
0.005
%
;
0
%
≤
Copper
≤
1
%
;
0
%
≤
Nickel
≤
1
%
;
0
%
≤
Boron
≤
0.05
%
;
0
%
≤
Magnesium
≤
0.05
%
;
a remainder of the composition being composed of iron and unavoidable impurities caused by processing;
a microstructure of steel sheet comprising, by area percentage, 10% to 20% Bainite, 80% to 92% Ferrite, wherein the aspect ratio of the grains of Bainite and Ferrite is less than 1.75 and a cumulated amount of Residual Austenite and Martensite from 0% to 10%.
17 . The hot rolled steel sheet according to claim 16 wherein the composition includes 0.35% to 0.75% of Silicon.
18 . The hot rolled steel sheet according to claim 16 wherein the composition includes 0.065% to 0.1% of Carbon.
19 . The hot rolled steel sheet according to claim 16 wherein the composition includes 0.02% to 0.07% of Niobium.
20 . The hot rolled steel sheet according to claim 16 wherein the composition includes 1.45% to 1.7% of Manganese.
21 . The hot rolled steel sheet according to claim 16 wherein the composition includes 0.01% to 0.06% of Titanium.
22 . The hot rolled steel sheet according to claim 16 wherein the composition includes 0.02% to 0.06% of Aluminum.
23 . The hot rolled steel sheet according to claim 16 wherein the cumulated amount of Residual Austenite and Martensite is from 0% to 5%.
24 . The hot rolled steel sheet according to claim 16 wherein the steel sheet has a hole expansion ratio of 75% or more.
25 . A method of production of a hot rolled steel sheet comprising the following successive steps:
providing a semi-finished product with a composition, expressed in percentage by weight:
0.06
%
≤
Carbon
≤
0.1
%
;
1.4
%
≤
Manganese
≤
1.8
%
;
0.3
%
≤
Silicon
≤
0.8
%
;
0.01
%
≤
Aluminum
≤
0.1
%
;
0.01
%
≤
Niobium
≤
0.09
%
;
0.01
%
≤
Titanium
≤
0.09
%
;
0.002
%
≤
Phosphorus
≤
0.02
%
;
0
%
≤
Sulfur
≤
0.005
%
;
0
%
≤
Nitrogen
≤
0.01
%
;
with
0.045
%
≤
Ti
+
Nb
≤
0.06
%
;
and one or more of the following optional elements:
0
%
≤
Chromium
≤
0.5
%
;
0
%
≤
Molybdenum
≤
0.4
%
;
0
%
≤
Vanadium
≤
0.4
%
;
0
%
≤
Calcium
≤
0.005
%
;
0
%
≤
Copper
≤
1
%
;
0
%
≤
Nickel
≤
1
%
;
0
%
≤
Boron
≤
0.05
%
;
0
%
≤
Magnesium
≤
0.05
%
;
a remainder of the composition being composed of iron and unavoidable impurities caused by processing;
reheating the semi-finished product to a temperature from 1200° C. to 1300° C.;
rolling the semi-finished product in the austenitic range wherein the hot rolling finishing temperature is from 850° C. to 975° C. to obtain a hot rolled steel strip;
cooling the hot rolled strip is cooled wherein the cooling starts immediately after the finishing of hot rolling;
then cooling the hot rolled strip from finishing of hot rolling to a cooling stop temperature range from 480° C. to 550° C. at a cooling rate greater than 20° C./s;
coiling the hot rolled strip from the coiling temperature range 480° C. to 550° C.; and
cooling the coiled hot rolled strip to room temperature to obtain a hot rolled steel sheet.
26 . The method according to claim 25 wherein the reheating temperature for semi-finished product is from 1200° C. to 1275° C.
27 . The method according to claim 25 wherein the hot rolling finishing temperature is from 880° C. to 930° C.
28 . The method according to claim 25 wherein the cooling rate for the step one of cooling is from 40° C./s to 120° C./s.
29 . A method for manufacturing a structural or safety part of a vehicle comprising employing the steel sheet as recited in claim 15 .
30 . A method for manufacturing a structural or safety part of a vehicle comprising employing the steel sheet according to the method as recited in claim 25 .Join the waitlist — get patent alerts
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