Method for manufacturing austenite-ferrite stainless steel with improved machinability

Patent metadata

Field	Value
Publication number	US-9797025-B2
Application number	US-201715409348-A
Country	US
Kind code	B2
Filing date	Jan 18, 2017
Priority date	Jul 7, 2010
Publication date	Oct 24, 2017
Grant date	Oct 24, 2017

Abstract

A method for manufacturing a plate, a band, or a coil of hot-rolled steel is provided. The method includes providing an ingot or a slab of steel with a desired composition and a microstructure composed of austenite and 35 to 65% ferrite by volume and hot rolling the ingot or slab at a temperature between 1150 and 1280° C. to obtain a plate, a band or a coil. A method for manufacturing a hot-rolled bar or wire of steel, a steel profile and a forged steel piece are also provided.

First claim

What is claimed is:

1. A method for manufacturing a plate, a band, or a coil of hot-rolled steel comprising the steps of:
providing an ingot or a slab of steel with a composition comprising in % by weight:
0.01%≦C≦0.10%
20.0%≦Cr≦24.0%
1.0%≦Ni≦3.0%
0.12%≦N≦0.20%
0.5%≦Mn≦2.0%
1.6%≦Cu≦3.0%
0.05%≦Mo≦1.0%
W≦0.15%
0.05%≦Mo+W/2≦1.0%
0.2%≦Si≦1.5%
Al≦0.05%
V≦0.5%
Nb≦0.5%
Ti≦0.5%
B≦0.003%
Co≦0.5%
REM≦0.1%
Ca≦0.03%
Mg≦0.1%
Se≦0.005%
O≦0.01%
S≦0.030%
P≦0.040%

the rest being iron and impurities resulting from the production and a microstructure being composed of austenite and 35 to 65% ferrite by volume, the composition furthermore obeying the following relations:
40≦IF≦65

with IF=10% Cr+5.1% Mo+1.4% Mn+24.3% Si+35% Nb+71.5% Ti−595.4% C−245.1% N−9.3% Ni−3.3% Cu−99.8; and
IRCGCU≧32.0

with IRCGCU=% Cr+3.3% Mo+2% Cu+16% N+2.6% Ni−0.7% Mn; and
0≦IU≦6.0

with IU=3% Ni+% Cu+% Mn−100% C−25% N−2(% Cr+% Si)−6% Mo+45; and
hot rolling the ingot or slab at a temperature between 1150 and 1280° C. to obtain the plate, the band or the coil.

2. The method as recited in claim 1 , wherein the plate obtained after hot rolling is a quarto plate and further comprising the steps of:
heat treating the quarto plate at a temperature between 900 and 1100° C.; and
cooling the quarto plate by quenching in air.

3. A method for manufacturing a hot-rolled bar or wire of steel comprising the steps of:
providing a continuously cast ingot or bloom of steel with a composition comprising in % by weight:
0.01%≦C≦0.10%
20.0%≦Cr≦24.0%
1.0%≦Ni≦3.0%
0.12%≦N≦0.20%
0.5%≦Mn≦2.0%
1.6%≦Cu≦3.0%
0.05%≦Mo≦1.0%
W≦0.15%
0.05%≦Mo+W/2≦1.0%
0.2%≦Si≦1.5%
Al≦0.05%
V≦0.5%
Nb≦0.5%
Ti≦0.5%
B≦0.003%
Co≦0.5%
REM≦0.1%
Ca≦0.03%
Mg≦0.1%
Se≦0.005%
O≦0.01%
S≦0.030%
P≦0.040%

the rest being iron and impurities resulting from the production and a microstructure being composed of austenite and 35 to 65% ferrite by volume, the composition furthermore obeying the following relations:
40≦IF≦65

with IF=10% Cr+5.1% Mo+1.4% Mn+24.3% Si+35% Nb+71.5% Ti−595.4% C−245.1% N−9.3% Ni−3.3% Cu−99.8; and
IRCGCU≧32.0

with IRCGCU=% Cr+3.3% Mo+2% Cu+16% N+2.6% Ni−0.7% Mn; and
0≧IU≧6.0

with IU=3% Ni+% Cu+% Mn−100% C−25% N−2(% Cr+% Si)−6% Mo+45;
hot rolling the continuously cast ingot or bloom at a temperature between 1150 and 1280° C. to obtain a bar or a wire coil; and
cooling the bar in air or cooling the wire coil in water.

4. The method as recited in claim 3 , further comprising the step of:
heating treating the bar or wire coil at a temperature between 900 and 1100° C.; and
cooling the bar or wire coil by quenching.

5. The method as recited in claim 3 , further comprising the step of:
cold drawing the bar or wire drawing the wire coil, at the end of the cooling.

6. The method as recited in claim 4 , further comprising the step of:
cold drawing the bar or wire drawing the wire coil, at the end of the cooling.

7. A method for manufacturing a steel profile comprising the steps of:
providing the-hot rolled bar manufactured by the method recited in claim 3 ; and
cold profiling the hot-rolled bar.

8. A method for manufacturing a forged steel piece comprising the steps of:
providing the-hot rolled bar manufactured by the method recited in claim 3 ;
cutting the hot-rolled bar into billets, and
forging of said billet between 1100° C. and 1280° C.

Assignees

• Arcelormittal
• Ugitech

Inventors

• Peultier Jerome
• Fanica Amelie
• Renaudot Nicolas
• Bourgin Christophe
• Chauveau Eric
• Mantel Marc

Classifications

• C21D8/06

  during manufacturing of rods or wires · CPC title

• C22C38/54

  with boron · CPC title

• C21D8/0226

  Hot rolling · CPC title

• C21D1/613

  Gases; Liquefied or solidified normally gaseous material · CPC title

• C21D1/60

  Aqueous agents · CPC title