Steel for tool-less hot forming or quenching with improved ductility

A technology of mechanical properties and parts, applied in the direction of manufacturing tools, heat treatment furnaces, heat treatment equipment, etc., can solve problems such as uneven performance and parts non-uniform structure

Active Publication Date: 2010-01-20
ARCELORMITTAL INVESTIGACION Y DESARROLLO SL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

These local variations in the degree of deformation or cooling rate may have the consequence that after heat treatment the part has a non-uniform structure and non-uniform properties

Method used

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  • Steel for tool-less hot forming or quenching with improved ductility
  • Steel for tool-less hot forming or quenching with improved ductility

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0059] Consider a hot-rolled or cold-rolled steel sheet having a thickness of 1.2-2mm, said sheet having the following composition by weight:

[0060] Table 1: Composition of steel (in weight %):

[0061] (underlined values ​​indicate features outside the scope of the invention)

[0062] steel

C

mn

Si

S

P

Al

Nb

Ti

N

other

A

0,059

1,646

0,022

0,004

0,016

0,024

0,048

0,067

0,005

Cu: 0,009 Mo: 0,003

Ni: 0,016 Cr: 0,027

Ca: 0,003

B

0,063

1,677

0,018

0,003

0,018

0,030

0,050

0,071

0,005

Cr：0,023

C

0,125

1,444

0,384

0,002

0,020

0,030

0,003

0,011

0,005

Cr：0,189

D

0,057

0,626

0,074

0,008

0,018

0,030 ...

Embodiment 2

[0078] Consider a sheet of steel B having the composition according to the invention detailed in Table 1 . The sheets with a thickness of 2 mm were precoated with the aluminum-based alloys specified in Table 1 . The sheet was heated at 900°C for 8 minutes and then hot stamped to make parts. Cooling rate V R is 60°C / s. Within the topography of the part, the equivalent deformation ε varies according to different regions: some parts are practically locally undeformed (ε = 0%), while others undergo a deformation of 20%. Microscopic observations, hardness measurements and tensile test specimens were taken in these different deformation regions. Yield strength varies from 430-475MPa, tensile strength is 580-650MPa and elongation at break is 17-22%. Thus, although the austenite grains are thermally deformed to a greater or lesser extent depending on the position considered, the steel and the method according to the invention are characterized by very homogeneous properties within...

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Abstract

The invention relates to a steel part having the following composition in wt %: 0.040% <= C <= 0.100%, 0.80% <= Mn <= 2.00%, Si <= 0.30%, S <= 0.005%, P<= 0.030%, 0.010% <= Al <= 0.070%, 0.015%<= Nb <= 0.100%, 0.030% <= Ti<= 0.080%, N <= 0.009%, Cu <= 0.100%, Ni <= 0.100%, Cr <= 0.100%, Mo <= 0.100%, Ca <= 0.006%, the balance of the composition consisting of iron and unavoidable impurities from the manufacturing process. The steel microstructure includes at least 75 % of equiaxed ferrite, martensite in an amount higher than or equal to5 % and lower than or equal to 20 %, and bainite in an amount lower than or equal to 10 %.

Description

technical field [0001] The invention relates to the manufacture of hot-rolled or cold-rolled steel parts having particularly advantageous and uniform strength, elongation and corrosion resistance after hot forming or quenching in an outil. Background technique [0002] For some applications, the aim is to produce steel parts with a combination of high tensile strength, high impact resistance and good corrosion resistance. Combinations of this type are particularly desirable in the automotive industry seeking to significantly lighten vehicles. This can be achieved in particular by using steel parts with high mechanical properties, the microstructure of which is martensitic or bainitic-martensitic: for example anti-intrusion parts of motor vehicles, structural parts or contribute to safety These properties are required for critical parts such as fascia beams and doors, or center pillar reinforcements. [0003] Thus, patent FR 2 780 984 discloses aluminium-coated steel sheets...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C21D1/18C21D6/00C21D7/13C21D8/02C21D8/04C21D9/48C22C38/02C22C38/04C22C38/06C22C38/12C22C38/14C23C2/12C23C2/06C23F17/00
CPCC21D2211/008C23C2/28C23C2/06C22C38/14C23C2/12C22C38/04C21D1/68C23C2/02C21D8/0205B32B15/013C21D8/0263C21D8/0478C22C38/12B32B15/012C21D8/0278C22C38/06C23C2/26C21D7/13C21D6/005C21D2211/005C21D8/0405C21D9/48C21D1/18C21D2211/002Y10T428/12757Y10T428/12799Y10T428/12972C23C2/29
Inventor J-P·洛朗T·马洛特
Owner ARCELORMITTAL INVESTIGACION Y DESARROLLO SL
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