Coated Steel Strips, Coated Stamped Products and Methods

Patent metadata

Field	Value
Publication number	US-2019271057-A1
Application number	US-201916413825-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 includesa 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 precoated steel product comprising:
a strip of base steel having a first side and a second side; and a precoating on at least one of the first side and the second side,
the precoating being made of an aluminum alloy and having a controlled thickness to create a precoated steel strip heat treatable to permit a full intermetallic alloying between the precoating and the strip of base steel without remelting of the precoating.

26 . The precoated steel product according to claim 25 , wherein the controlled thickness of said pre-coating is from 20 to 33 micrometers at every location on at least one of said first and second sides.

27 . The precoated steel product according to claim 25 , wherein the controlled thickness of said pre-coating is from 20 to 33 micrometers at every location on both said first and second sides.

28 . The precoated steel product 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%; 0.005%<boron<0.08%; iron; and impurities inherent in processing.

29 . The precoated steel product according to claim 28 , 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%; 0.005%<boron<0.01%, iron; and impurities inherent in processing.

30 . The precoated steel product of claim 28 , wherein the base steel comprises 20 ppm or less of sulfur.

31 . The precoated steel product of claim 25 , wherein the aluminum alloy pre-coating 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.

32 . The precoated steel product of claim 25 , wherein the precoated steel strip is heat treatable to form a coating comprising, proceeding from the base steel outwards:
(a) an Interdiffusion layer, (b) an Intermediate layer, (c) an Intermetallic layer, and (d) a Superficial layer; wherein the coating has a thickness greater than 30 micrometers and wherein said layer (a) has a thickness less than 15 micrometers.

33 . The precoated steel product according to claim 32 , wherein the said layers (c) and (d) are quasi continuous by occupying at least 90% of a level corresponding to each said layer and wherein less than 10% of layer (c) is present at an extreme surface of the product.

34 . The precoated steel product according to claim 32 , wherein the Interdiffusion layer comprises the following components by weight based on total weight: 86 to 95% Fe, 4 to 10% Al, and 0 to 5% Si.

35 . The precoated steel product according to claim 32 , wherein the Intermediate layer comprises the following components by weight based on total weight: 39 to 47% Fe, 53 to 61% Al, and 0 to 2% Si.

36 . The precoated steel product according to claim 32 , wherein the Intermetallic layer comprises the following components by weight based on total weight: 62 to 67% Fe, 30 to 34% Al, and 2 to 6% Si.

37 . The precoated steel product according to claim 32 , wherein the Superficial layer comprises the following components by weight based on total weight: 39 to 47% Fe, 53 to 61% Al, and 0 to 2% Si.

38 . The precoated steel product according to claim 34 ,
wherein the Intermediate layer comprises the following components by weight based on total weight: 39 to 47% Fe, 53 to 61% Al, and 0 to 2% Si; wherein the Intermetallic layer comprises the following components by weight based on total weight: 62 to 67% Fe, 30 to 34% Al, and 2 to 6% Si; and wherein the Superficial layer comprises the following components by weight based on total weight: 39 to 47% Fe, 53to 61% Al, and 0 to 2% Si.

39 . The precoated steel product according to claim 32 , wherein the Interdiffusion layer has a thickness of from 1 micron to 15 microns.

40 . A precoated steel product comprising:
a strip of base steel having a first side and a second side; and a precoating on at least one of the first side and the second side,
the precoating being made of an aluminum alloy and having a controlled thickness less than 33 micrometers to create a precoated steel strip heat treatable to a martensitic structure with a mechanical resistance exceeding 1450 MPa.

41 . The precoated steel product according to claim 40 , wherein the controlled thickness of said pre-coating is from 20 to 33 micrometers at every location on at least one of said first and second sides.

42 . The precoated steel product according to claim 40 , wherein the controlled thickness of said pre-coating is from 20 to 33 micrometers at every location on both said first and second sides.

43 . The precoated steel product of claim 40 , wherein the base steel comprises the following components by weight based on total weight:
0.15%<carbon<0.5%; 0.5%<manganese<3%; 0.01%<silicon<0.5%; 0.01%<chromium<1%; titanium<0.2%; aluminum<0.1%; phosphorus<0.1%; sulfur<0.05%; 0.005%<boron<0.08%; iron; and impurities inherent in processing.

44 . The precoated steel product 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 precoated steel product of claim 43 , wherein the base steel comprises 20 ppm or less of sulfur.

46 . The precoated steel product of claim 40 , wherein the aluminum alloy pre-coating 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.

47 . The precoated steel product of claim 40 , wherein the precoated steel strip is heat treatable to form a coating comprising, proceeding from the base steel outwards:
(a) an Interdiffusion layer, (b) an Intermediate layer, (c) an Intermetallic layer, and (d) a Superficial layer; wherein the coating has a thickness greater than 30 micrometers and wherein said layer (a) has a thickness less than 15 micrometers.

48 . The precoated steel product according to claim 47 , wherein the said layers (c) and (d) are quasi continuous by occupying at least 90% of a level corresponding to each said layer and wherein less than 10% of layer (c) is present at an extreme surface of the product.

49 . The precoated steel product according to claim 47 , wherein the Interdiffusion layer comprises the following components by weight based on total weight: 86 to 95% Fe, 4 to 10% Al, and 0 to 5% Si.

50 . The precoated steel product according to claim 47 , wherein the Intermediate layer comprises the following components by weight based on total weight: 39 to 47% Fe, 53 to 61% Al, and 0 to 2% Si.

51 . The precoated steel product according to claim 47 , wherein the Intermetallic layer comprises the following components by weight based on total weight: 62 to 67% Fe, 30 to 34% Al, and 2 to 6% Si.

52 . The precoated steel product according to claim 47 , wherein the Superficial layer c

Assignees

• Arcelormittal

Inventors

• Drillet Pascal
• Spehner Dominique
• Kefferstein Ronald

Classifications

• C23C2/40

  Plates; Strips · CPC title

• Y10T428/12396

  Discontinuous surface component · CPC title

• Y10T428/12389

  having variation in thickness · 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

• Y10T428/12757

  Fe · CPC title