Method for producing a welded component consisting of a formed high-strength steel, and a component produced in this manner

Patent metadata

Field	Value
Publication number	US-12397371-B2
Application number	US-202017614204-A
Country	US
Kind code	B2
Filing date	May 25, 2020
Priority date	May 27, 2019
Publication date	Aug 26, 2025
Grant date	Aug 26, 2025

Abstract

A welded component having mechanical properties in a welding seam region comparable or better to those in the non-influenced base material via a method including producing a hot-rolled steel product made of a high-strength air-hardenable steel with a material thickness of at least 1.5 mm having a chemical composition by mass in one embodiment of: C: 0.03 to 0.4; Mn: 1.0 to 4.0; Si: 0.09 to 2.0; Al: 0.02 to 2.0; P<=0.1; S<=0.1; N: 0.001 to 0.5; Ti: 0.01 to 0.2; Cr: 0.05 to 2.0; B: 0.001 to 0.1; Mo: 0.01 to 1.0; V: 0.01 to 0.2; optionally: Ni: 0.02 to 1.0; Nb: 0.01 to 0.1; and residual iron including conventional steel-accompanying elements, subsequently air hardening the produced hot-rolled steel product, then deforming the hot-rolled steel product in the air-hardened state to form a component, and producing welding connections using a fusion welding process on the component.

First claim

The invention claimed is:

1. A method for producing a welded component, comprising:
producing a hot-rolled steel product from a high-strength air-hardenable steel having a material thickness of at least 1.5 mm, wherein the hot-rolled steel product comprises a chemical composition in mass % as follows:
C: 0.08 to 0.10,
Mn: 1.80 to 2.00,
Si: 0.25 to 0.30,
Al: 0.02 to 0.05,
P: ≤0.020,
S: ≤0.010,
N: 0.0030 to 0.0080,
Ti: 0.020 to 0.030,
Cr: 0.70 to 0.80,
B: 0.0025 to 0.0035,
Mo: 0.15 to 0.30,
V: 0.05 to 0.08,

with a remainder being iron including typical steel-associated elements,
subsequently hardening solely by cooling in air the hot-rolled steel product produced, after which the hot-rolled, air-hardened steel product has a minimum yield strength Rp0.2 of 450 MPa, a minimum tensile strength Rm of 700 MPa and/or an elongation at fracture A5 of at least 6% and a complex phase microstructure with a banite content of more than 50%;
forming the hot-rolled steel product in the air-hardened state into a component; and
producing welded connections by fusion welding on the component.

2. The method of claim 1 , wherein the hot-rolled steel product further comprises in mass % in said producing a hot-rolled steel product:
Ni: 0.02 to 1.0,
Nb: 0.01 to 0.1,
with the remainder being iron including typical steel-associated elements.

3. The method of claim 1 , wherein said method consists exclusively of the following steps:
producing a hot-rolled steel product from a high-strength air-hardenable steel having a material thickness of at least 1.5 mm, wherein the hot-rolled steel product comprises the following chemical composition in mass %:
C: 0.08 to 0.10,
Mn: 1.80 to 2.00,
Si: 0.25 to 0.30,
Al: 0.02 to 0.05,
P: ≤0.020,
S: ≤0.010,
N: 0.0030 to 0.0080,
Ti: 0.020 to 0.030,
Cr: 0.70 to 0.80,
B: 0.0025 to 0.0035,
Mo: 0.15 to 0.30,
V: 0.05 to 0.08,

with the remainder being iron including typical steel-associated elements,
subsequently hardening solely by cooling in air the hot-rolled steel product produced, after which the hot-rolled, air-hardened steel product has a minimum yield strength Rp0.2 of 450 MPa, a minimum tensile strength Rm of 700 MPa and/or an elongation at fracture A5 of at least 6% and a complex phase microstructure with a banite content of more than 50%;
forming the hot-rolled steel product in the air-hardened state into a component; and
producing welded connections by fusion welding on the component.

4. The method as claimed in claim 1 , wherein said forming is a conventional cold sheet forming method.

5. The method as claimed in claim 4 , wherein the conventional cold sheet forming comprises deep drawing, folding, roll-profiling, bending or flanging.

6. The method as claimed in claim 1 , wherein the forming is carried out at a temperature in a range of −5° C. to 40° C.

7. The method as claimed in claim 6 , wherein the forming is carried out at room temperature in the range of 15° C. to 25° C.

8. The method as claimed in claim 1 , wherein the fusion welding comprises metal arc welding or beam welding.

9. The method as claimed in claim 8 , wherein the metal arc welding comprises protective gas welding, and wherein the beam welding comprises laser beam welding.

10. The method as claimed in claim 1 , wherein the hot-rolled, air-hardened steel product has a complex phase microstructure with a bainite content of more than 80%.

11. The method as claimed in claim 1 , wherein the hot-rolled, air-hardened steel product has a complex phase microstructure with a bainite content of more than 90%.

Assignees

• Salzgitter Flachstahl Gmbh

Inventors

• Otto Manuel

Classifications

• C21D8/02

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

• C21D8/04

  to produce plates or strips for drawing, e.g. for deep-drawing · CPC title

• C22C38/32

  with boron · CPC title

• C22C38/28

  with titanium or zirconium · CPC title

• C22C38/24

  with vanadium · CPC title