US 7,018,488 B2 · Steel pipe for use in reinforcement of automobile and method for production thereof

Abstract

A steel tube having a composition which contains: 0.05 to 0.30% of C; 1.8 to 4.0% of Mn; Si; and Al is subjected to a diameter-reducing rolling process in which the total diameter-reduction rate is no less than 20% and the temperature at which the diameter-reducing rolling process is finished is no higher than 800° C., whereby a structure constituted of martensite and/or bainite or further of ferrite is obtained as a transformation product from the deformed γ. As a result, a steel tube having tensile strength of 1000 MPa or more and excellent three-point-bending property can be obtained. The composition of the steel tube of the present invention may further include at least one type of element selected from the group consisting of Cu, Ni, Cr and Mo, or at least one type of element selected from the group consisting of Nb, V, Ti and B, or at least of one type selected from the group consisting of REM and Ca.

Claims9

Dependent claims

A steel tube for reinforcing a automobile door, having a composition comprising:

0.05 to 0.22 mass % of C;
0.01 to 2.0 mass % of Si;
2.5 to 3.5 mass % of Mn;
0.005 to 0.10 mass % of Al;
and
the remainder as Fe and unavoidable impurities,
wherein the steel tube has tensile strength of no less than 1000 MPa and has an absorbed energy before buckling of at least 1160 E(J) and is excellent in three-point-bending property.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application

10/049,510Filed 14 Jun 2001

Priority

JP 2000-17824614 Jun 2000

Published

US 2003/0051782 A120 Mar 2003

Granted

28 Mar 2006

Term ends

Not estimatedThe source records don’t support an estimate.

Classification11 codes

C22C 38/38
Containing chromium: with more than 1.5% by weight of manganese
C21D 8/10
Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment: during…
C22C 38/002
Ferrous alloys, e.g. steel alloys: containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
C22C 38/04
Ferrous alloys, e.g. steel alloys: containing manganese

Steel pipe for use in reinforcement of automobile and method for production thereof

Life of this patent

Steel pipe for use in reinforcement of automobile and method for production thereof

Life of this patent

Abstract

Claims9