Non-scaling heat-treatable steel and method for producing a non-scaling component from said steel

Patent metadata

Field	Value
Publication number	US-10036085-B2
Application number	US-201314387158-A
Country	US
Kind code	B2
Filing date	Mar 19, 2013
Priority date	Mar 23, 2012
Publication date	Jul 31, 2018
Grant date	Jul 31, 2018

Abstract

A non-scaling heat-treatable steel with particular suitability for producing hardened or die-hardened components is disclosed, characterized by the following chemical composition in % by weight: C 0.04-0.50; Mn 0.5-6.0; Al 0.5-3.0; Si 0.05-3.0; Cr 0.05-3.0; Ni less than 3.0; Cu less than 3.0; Ti 0.010-≤0.050; B 0.0015-≤0.0040; P less than 0.10; S less than 0.05; N less than 0.020; remainder iron and unavoidable impurities. Further disclosed is a method for producing a non-scaling hardened component from the steel and a method for producing a hot strip from a steel.

First claim

The invention claimed is:

1. A method for producing a component from steel comprising:
heating a pre-product comprising a following chemical composition in weight %:
C: 0.04-0.50
Mn: 0.5-6.0
Al: >1.5-≤3.0
Si: 0.05-3.0
Cr: 0.05-3.0
Ni: less than 3.0
Cu: less than 3.0
Ti: 0.010-≤0.050
B: 0.0015-≤0.0040
P: less than 0.10
S: less than 0.05
N: less than 0.020,
remainder iron and unavoidable impurities, in a nitrogen-containing atmosphere to austenizing temperature;
lowering an oxygen content or humidity in the nitrogen-containing atmosphere to a level sufficient to keep a dew point at below 0° C. and to form a layer of Al 2 O 3 on a surface of the heated pre-product and thereby effectively inhibit scaling of iron in the pre-product; and
quenching the pre-product.

2. The method of claim 1 , wherein the level of the oxygen content or humidity in the nitrogen-containing atmosphere is such as to keep the dew point below −10° C.

3. The method of claim 1 , wherein the level of the oxygen content or humidity in the nitrogen-containing atmosphere is such as to keep the dew point below −20° C.

4. The method of claim 1 , wherein the level of the oxygen content or humidity in the nitrogen-containing atmosphere is such as to keep the dew point below −30° C.

5. The method of claim 1 , wherein the heating to austenizing temperature is realized through induction, conduction, or radiation.

6. The method of claim 1 , Fan hot or cold rolling a sheet metal to produce the pre-product.

7. The method of claim 1 , further comprising seamlessly hot rolling a tube to produce the pre-product.

8. The method of claim 1 , further comprising:
casting a melt to a pre-strip in a horizontal strip casting system; and
hot rolling the pre-strip to form the pre-product with a deformation degree of at least 50%.

9. The method of claim 8 , further comprising supplying the melt onto a rotating conveyor belt of the horizontal strip casting system at a speed which equals a speed of the rotating conveyor belt.

10. The method of claim 8 , further comprising evenly cooling all surface areas of the pre-strip, across a width of the conveyor belt so as to substantially fully solidify the ore-strip when exiting the conveyor belt.

11. The method of claim 10 , further comprising after full solidification of the pre-strip, passing the pre-strip through a homogenization zone.

12. The method of claim 11 , further comprising cutting the pre-strip into plates after undergoing homogenization.

13. The method of claim 12 , further comprising after cutting the pre-strip to plates, heating the plates to rolling temperature and subsequently rolling the plates.

14. The method of claim 11 , further comprising coiling the pre-strip after undergoing homogenization.

15. The method of claim 14 , further comprising after the coiling uncoiling the pre-strip, heating the pre-strip to rolling temperature and rolling the pre-strip.

16. The method of claim 15 , wherein the pre-strip is reheated prior to the uncoiling.

17. The method of claim 8 , further comprising subjecting the pre-strip to the rolling process in-line and subsequently coiling the pre-strip.

18. The method of claim 8 , wherein the deformation degree during rolling is >70%.

19. The method of claim 8 , wherein the deformation degree during rolling is >90%.

20. The method of claim 10 , further comprising cold rolling the pre-strip after the cooling.

21. The method of claim 1 , wherein the nitrogen containing atmosphere contains H 2 , CO and CO 2 .

Assignees

• Salzgitter Flachstahl Gmbh

Inventors

• Schöttler Joachim
• Luther Friedrich
• Mütze Stefan

Classifications

• B22D11/0631

  formed by a travelling straight surface, e.g. through-like moulds, a belt · CPC title

• C22C38/28

  with titanium or zirconium · CPC title

• C22C38/58 Primary

  with more than 1.5% by weight of manganese · CPC title

• B21B1/466

  in a non-continuous process, i.e. the cast being cut before rolling · CPC title

• C21D9/52

  for wires; for strips {; for rods of unlimited length} · CPC title