Metal sheet, method of producing metal sheet, method of producing molded product of metal sheet, and molded product of metal sheet

Patent metadata

Field	Value
Publication number	US-11035022-B2
Application number	US-201917044106-A
Country	US
Kind code	B2
Filing date	Apr 2, 2019
Priority date	Apr 2, 2018
Publication date	Jun 15, 2021
Grant date	Jun 15, 2021

Abstract

Provided are a metal sheet, a method of producing a metal sheet, a method of producing a molded product of a metal sheet, and a molded product of a metal sheet, in which occurrence of surface roughness is inhibited. Provided are a metal sheet satisfying conditions (a1), (b1) or (c1) at the surface and a method for producing the metal sheet. Also provided are a method for producing a molded product of a metal sheet using the metal sheet, and a molded product of the metal sheet. (a1) The area fraction of crystal grains having a crystal orientation divergent by 20° or more from a (111) plane and by 20° or more from a (001) plane is from 0.25 to 0.35, and the average crystal grain size is less than 16 μm. (b1) The area fraction of crystal grains having a crystal orientation divergent by 20° or more from a (111) plane and by 20° or more from a (001) plane is from 0.15 to 0.30, and the average crystal grain size is 16 μm or more. (c1) The area fraction of crystal grains with a Taylor Factor value from 3.0 to 3.4, when assuming plane strain tensile deformation in the transverse direction, is from 0.18 to 0.40.

First claim

The invention claimed is:

1. A metal sheet having a bcc structure and satisfying the following condition (a1) or (b1) at a surface thereof:
(a1) an area fraction of crystal grains having a crystal orientation divergent by 20° or more from a (111) plane parallel to a surface of the metal sheet and by 20° or more from a (001) plane is from 0.25 to 0.35, and an average crystal grain size is less than 16 μm; or
(b1) an area fraction of crystal grains having a crystal orientation divergent by 20° or more from a (111) plane parallel to a surface of the metal sheet and by 20° or more from a (001) plane is from 0.15 to 0.30, and an average crystal grain size is 16 μm or more,
wherein the metal sheet is a steel sheet;
wherein the steel sheet is a ferrite-based steel sheet having a chemical composition of:
C: from 0.0040% by mass to 0.0100% by mass;
Si: from 0% by mass to 1.0% by mass;
Mn: from 0.90% by mass to 2.00% by mass;
P: from 0.050% by mass to 0.200% by mass;
S: from 0% by mass to 0.010% by mass;
Al: from 0.00050% to 0.10% by mass;
N: from 0% by mass to 0.0040% by mass;
Ti: from 0.0010% by mass to 0.10% by mass;
Nb: from 0.0010% by mass to 0.10% by mass;
B: from 0% by mass to 0.003% by mass;
a total of one or more of Cu or Sn: from 0% by mass to 0.10% by mass;
a total of one or more of Ni, Ca, Mg, Y, As, Sb, Pb, or REM: from 0% by mass to 0.10% by mass; and
a balance: Fe and impurities,
wherein a value of F1 as defined in the following Formula (1) is from 0.5 to 1.0:
F1=(C/12+N/14+S/32)/(Ti/48+Nb/93)  Formula (1).

2. The metal sheet according to claim 1 , wherein the steel sheet is the ferrite-based steel sheet having a ferrite fraction of 50% or more of a metallic structure at a surface thereof.

3. The metal sheet according to claim 1 , wherein the chemical composition of the steel sheet contains one or two or more of:
the total of one or more of Cu or Sn: from 0.002% by mass to 0.10% by mass; and
the total of one or more of Ni, Ca, Mg, Y, As, Sb, Pb, or REM: from 0.005% by mass to 0.10% by mass.

4. A method of producing the metal sheet according to claim 3 , the method comprising:
cold-rolling a hot-rolled sheet with a draft of 70% or more to obtain a cold-rolled sheet; and
annealing the cold-rolled sheet under conditions of an annealing temperature of a recrystallization temperature or more and the recrystallization temperature +25° C. or less, a temperature irregularity at the sheet surface of ±10° C. or less, and an annealing time of 100 seconds or less;
thereby producing the metal sheet of claim 3 .

5. A method of producing the metal sheet according to claim 1 , the method comprising:
cold-rolling a hot-rolled sheet with a draft of 70% or more to obtain a cold-rolled sheet; and
annealing the cold-rolled sheet under conditions of an annealing temperature of a recrystallization temperature or more and the recrystallization temperature +25° C. or less, a temperature irregularity at the sheet surface of ±10° C. or less, and an annealing time of 100 seconds or less;
thereby producing the metal sheet of claim 1 .

6. A metal sheet having a bcc structure and satisfying the following condition (c1) at a surface thereof:
(c1) an area fraction of crystal grains with a Taylor Factor value from 3.0 to 3.4, when assuming plane strain tensile deformation in a transverse direction in a plane of the metal sheet, is from 0.18 to 0.40,
wherein the metal sheet is a steel sheet;
wherein the steel sheet is a ferrite-based steel sheet having a chemical composition of:
C: from 0.0040% by mass to 0.0100% by mass;
Si: from 0% by mass to 1.0% by mass;
Mn: from 0.90% by mass to 2.00% by mass;
P: from 0.050% by mass to 0.200% by mass;
S: from 0% by mass to 0.010% by mass;
Al: from 0.00050% to 0.10% by mass;
N: from 0% by mass to 0.0040% by mass;
Ti: from 0.0010% by mass to 0.10% by mass;
Nb: from 0.0010% by mass to 0.10% by mass;
B: from 0% by mass to 0.003% by mass;
a total of one or more of Cu or Sn: from 0% by mass to 0.10% by mass;
a total of one or more of Ni, Ca, Mg, Y, As, Sb, Pb, or REM: from 0% by mass to 0.10% by mass; and
a balance: Fe and impurities,
wherein a value of F1 as defined in the following Formula (1) is from 0.5 to 1.0:
F1=(C/12+N/14+S/32)/(Ti/48+Nb/93)  Formula (1).

7. The metal sheet according to claim 6 , wherein the steel sheet is the ferrite-based steel sheet having a ferrite fraction of 50% or more of a metallic structure at a surface thereof.

8. The metal sheet according to claim 6 , wherein the chemical composition of the steel sheet contains one or two or more of:
the total of one or more of Cu or Sn: from 0.002% by mass to 0.10% by mass; and
the total of one or more of Ni, Ca, Mg, Y, As, Sb, Pb, or REM: from 0.005% by mass to 0.10% by mass.

9. A method of producing the metal sheet according to claim 6 , the method comprising:
cold-rolling a hot-rolled sheet with a draft of 70% or more to obtain a cold-roiled sheet; and
annealing the cold-rolled sheet under conditions of an annealing temperature of a recrystallization temperature or more and the recrystallization temperature +25° C. or less, a temperature irregularity at the sheet surface of ±10° C. or less, and an annealing time of 100 seconds or less;
thereby producing the metal sheet of claim 6 .

Assignees

• Nippon Steel Corp

Inventors

• Kubo Masahiro
• Nakazawa Yoshiaki

Classifications

• C21D8/02

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• C22C38/005

  containing rare earths, i.e. Sc, Y, Lanthanides · CPC title

• C22C38/002

  containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60 · CPC title

• C22C38/001

  containing N · CPC title

• C21D9/46 Primary

  for sheet metals · CPC title