Coated Steel Strips, Coated Stamped Products and Methods

Patent metadata

Field	Value
Publication number	US-2019271055-A1
Application number	US-201916413774-A
Country	US
Kind code	A1
Filing date	May 16, 2019
Priority date	Oct 30, 2006
Publication date	Sep 5, 2019
Grant date	—

Abstract

A pre-coated steel strip is provided. The steel strip includes a strip of base steel having a length, a width, a first side, and a second side. The length of the strip is at least 100 m and the width is at least 600 mm. An aluminum or an aluminum alloy pre-coating is on at least part of at least one of the first or second sides of the strip of base steel. A thickness tp of the pre-coating is from 20 to 33 micrometers at every location on at least one of the first or second sides. Processes, coated stamped products and land motor vehicles are also provided.

First claim

1 - 24 . (canceled)

25 . A method for producing a precoated steel strip, the method comprising:
hot dip coating a strip of base steel having a length, a width, a first side, and a second side in an aluminum alloy to precoat at least one of the first and second sides of the strip of base steel with the aluminum alloy to define a precoating; passing the precoated strip between rollers on the first and second sides; and reducing fouling on the rollers by controlling a thickness of the precoating upstream of the rollers.

26 . The method of claim 25 , wherein the controlling the thickness comprises controlling the thickness in both a longitudinal and a tranverse direction of the strip.

27 . The method of claim 25 , wherein the controlling the thickness comprises controlling the thickness to be from 20 to 33 micrometers at every location on at least one of said first and second sides.

28 . The method of claim 25 , wherein the controlling the thickness comprises controlling the thickness to be from 20 to 33 micrometers at every location on both said first and second sides.

29 . The method of claim 25 , wherein the base steel comprises the following components by weight based on total weight:
0.15%<carbon<0.5%; 0.5%<manganese<3%; 0.1%<silicon<0.5%; 0.01%<chromium<1%; titanium<0.2%; aluminum<0.1%; phosphorus<0.1%; sulfur<0.05%; 0.0005%<boron<0.08%; iron; and impurities inherent in processing.

30 . The method according to claim 29 , wherein the base steel comprises the following components by weight based on total weight:
0.20%<carbon<0.5%; 0.8%<manganese<1.5%; 0.1%<silicon<0.35%; 0.01%<chromium<1%; titanium<0.1%; aluminum<0.1%; phosphorus<0.05%; sulfur<0.03%; 0.0005%<boron<0.01%, iron; and impurities inherent in processing.

31 . The method of claim 29 , wherein the base steel comprises 20 ppm or less of sulfur.

32 . The method according to claim 29 , wherein a ratio of titanium to nitrogen in the base steel in weight % is in excess of 3.42.

33 . The method of claim 25 , wherein the aluminum alloy pre-coating further comprises from 8 to 11% silicon by weight and from 2% to 4% iron by weight, the remainder being aluminum and impurities inherent in processing.

34 . The method of claim 25 , further comprising measuring the thickness.

35 . The method of claim 34 , wherein the measuring the thickness includes measuring the thickness with a plurality of thickness gauges located at different distances in a transverse direction of the strip.

36 . The method of claim 25 , wherein the hot dip coating includes hot dip coating the strip in a bath, and the controlling the thickness includes blowing gas onto the strip after the strip exits from the bath.

37 . The method of claim 36 , wherein the blowing includes blowing gas with a system of nozzles.

38 . The method of claim 25 , wherein the controlling the thickness includes controlling the thickness such that upon subsequent hot stamping there is complete intermetallic alloying between the precoating and the base steel.

39 . A method for producing a precoated steel strip, the method comprising:
coating a strip of base steel having a length, a width, a first side, and a second side in aluminum or an aluminum alloy to precoat at least one of the first and second sides of the strip of base steel with the aluminum alloy to define a precoating; passing the precoated strip between rollers on the first and second sides; and reducing fouling on the rollers by controlling a thickness of the precoating upstream of the rollers.

40 . The method of claim 39 , wherein the controlling the thickness comprises controlling the thickness in both a longitudinal and a tranverse direction of the strip.

41 . The method of claim 39 , wherein the controlling the thickness comprises controlling the thickness to be from 20 to 33 micrometers at every location on at least one of said first and second sides.

42 . The method of claim 39 , wherein the controlling the thickness comprises controlling the thickness to be from 20 to 33 micrometers at every location on both said first and second sides.

43 . The method of claim 39 , wherein the base steel comprises the following components by weight based on total weight:
0.15%<carbon<0.5%; 0.5%<manganese<3%; 0.1%<silicon<0.5%; 0.01%<chromium<1%; titanium<0.2%; aluminum<0.1%; phosphorus<0.1%; sulfur<0.05%; 0.0005%<boron<0.08%; iron; and impurities inherent in processing.

44 . The method according to claim 43 , wherein the base steel comprises the following components by weight based on total weight:
0.20%<carbon<0.5%; 0.8%<manganese<1.5%; 0.1%<silicon<0.35%; 0.01%<chromium<1%; titanium<0.1%; aluminum<0.1%; phosphorus<0.05%; sulfur<0.03%; 0.0005%<boron<0.01%, iron; and impurities inherent in processing.

45 . The method of claim 43 , wherein the base steel comprises 20 ppm or less of sulfur.

46 . The method according to claim 43 , wherein a ratio of titanium to nitrogen in the base steel in weight % is in excess of 3.42.

47 . The method of claim 39 , wherein the aluminum or aluminum alloy pre-coating further comprises from 8 to 11% silicon by weight and from 2% to 4% iron by weight, the remainder being aluminum and impurities inherent in processing.

48 . The method of claim 39 , further comprising measuring the thickness.

49 . The method of claim 48 , wherein the measuring the thickness includes measuring the thickness with a plurality of thickness gauges located at different distances in a transverse direction of the strip.

50 . The method of claim 39 , wherein the coating includes hot dip coating in a bath, and the controlling the thickness includes blowing gas onto the strip after the strip exits from the bath.

51 . The method of claim 50 , wherein the blowing includes blowing gas with a system of nozzles.

52 . The method of claim 39 , wherein the controlling the thickness includes controlling the thickness such that upon subsequent hot stamping there is complete intermetallic alloying between the precoating and the base steel.

Assignees

• Arcelormittal

Inventors

• Drillet Pascal
• Spehner Dominique
• Kefferstein Ronald

Classifications

• C23C2/12

  Aluminium or alloys based thereon · CPC title

• C21D9/46 Primary

  for sheet metals · CPC title

• Y10T428/12757

  Fe · CPC title

• Y10T428/12396

  Discontinuous surface component · CPC title

• B32B15/012

  one layer being formed of an iron alloy or steel, another layer being formed of aluminium or an aluminium alloy · CPC title