Iron-carbon-manganese austenitic steel sheet with excellent resistance to delayed cracking

Patent metadata

Field	Value
Publication number	US-2016010187-A1
Application number	US-201514672906-A
Country	US
Kind code	A1
Filing date	Mar 30, 2015
Priority date	Jul 11, 2006
Publication date	Jan 14, 2016
Grant date	—

Abstract

An austenitic steel sheet excellent in resistance to delayed cracking is provided. The composition of said steel comprises in weight:
0.35%≦C≦1.05% 15%≦Mn≦26% Si≦3% Al≦0.050% S≦0.030% P≦0.080% N≦0.1%, at least one metallic element X chosen among vanadium, titanium, niobium, molybdenum, chromium 0.050%≦V≦0.50%, 0.040%≦Ti≦0.50% 0.070%≦Nb≦0.50% 0.14%≦Mo≦2% 0.070%≦Cr≦2%.

The composition may optionally include B, Ni and/or Cu. The remainder of the composition includes iron and unavoidable impurities inherent to fabrication, including hydrogen. The quantity Xp of the at least one metallic element under the form of carbides, nitrides or carbonitrides is, in weight:
0.030%≦Vp≦0.40% 0.030%≦Tip≦0.50% 0.040%≦Nbp≦0.40% 0.14%≦Mop≦0.44% 0.070%≦Crp≦0.6%.

The hydrogen content Hmax designating the maximal hydrogen content that can be measured from a series of at least five specimens, and the quantity Xp, in weight, is such that:

1000


H
max

X
P

≤

3.3
.

First claim

1 : An austenitic steel sheet excellent in resistance to delayed cracking, the composition of said steel comprising, in weight:
0.35%≦C≦1.05% 15%≦Mn≦26% Si≦3% Al≦0.050% S≦0.030% P≦0.080% N≦0.1%, and
at least one metallic element X chosen among vanadium, titanium, niobium, molybdenum, chromium
0.050%≦V≦0.50%,
0.040%≦Ti≦0.50%
0.070%≦Nb≦0.50%
0.14%≦Mo≦2%
0.070%≦Cr≦2%

the remainder being iron and unavoidable impurities inherent to fabrication, including hydrogen, the quantity X p of said at least one metallic element under the form of carbides, nitrides or carbonitrides being, in weight:
0.030%≦V p ≦0.40%
0.030%≦Ti p ≦0.50%
0.040%≦Nb p ≦0.40%
0.14%≦Mo p ≦0.44%
0.070%≦Cr p ≦0.6%

the hydrogen content H max designating the maximal hydrogen content that can be measured from a series of at least five specimens, and the quantity X p , in weight, being such that:

1000


H
max

X
P

≤

3.3
.

2 : A steel sheet according to claim 1 , wherein

1000


H
max

X
P

≤

2.5
.

3 : A steel sheet according to claim 1 , wherein said sheet comprises a zinc or zinc-Y alloy coating, wherein element Y is one or more of Ni, Cr, Mg but not Fe or Mn.

4 : A coated steel sheet, comprising a base steel having a zinc or zinc-Y alloy coating, wherein element Y is one or more of Ni, Cr, Mg but not Fe or Mn, on the said base steel, the composition of said base steel comprising, in weight
0.35%≦C≦1.05% 15%≦Mn≦26% Si≦3% Al≦0.050% S≦0.030% P≦0.080% N≦0.1%, and
at least one metallic element X chosen among vanadium, titanium, niobium, molybdenum, chromium
0.050%≦V≦0.50%,
0.040%≦Ti≦0.50%
0.070%≦Nb≦0.50%
0.14%≦Mo≦2%
0.070%≦Cr≦2%

the remainder being iron and unavoidable impurities inherent to fabrication, the quantity Xp of said at least one metallic element under the form of carbides, nitrides or carbonitrides being, in weight:
0.030%≦V p ≦0.40%
0.030%≦Ti p ≦0.50%
0.040%≦Nb p ≦0.40%
0.14%≦Mo p ≦0.44%
0.070%≦Cr p ≦0.6%

the thickness of said coating being less or equal to 50 micrometers, said coating comprising at its interface with the said base material, an iron and manganese rich-Zn alloyed layer, the thickness of said alloyed layer being greater than or equal to 1 micrometer.

5 : A steel sheet according to claim 4 , wherein the thickness of said alloyed layer is greater than or equal to 4 micrometers.

6 : Steel sheet according to claim 4 , wherein the thickness of said alloyed layer is greater than or equal to 7 micrometers.

7 : A coated steel sheet with composition according to claim 4 , comprising a base steel with a zinc or zinc-Y alloy coating on the said base steel, wherein said sheet comprises a metallic coating layer acting as an hydrogen barrier between said steel and said zinc or zinc-Y alloy coating.

8 : A steel sheet according to claim 7 , wherein the metal of said metallic coating layer is chosen among Sn, Ni, Ti, Cu, W, or Al, or alloys based on these said metals.

9 : A steel sheet according to claim 7 , wherein said metallic coating layer has a thickness between 0.1 and 1 micrometer.

10 : A steel sheet according to claim 1 , wherein said composition comprises, in weight
0.35%≦C≦0.50%.

11 : A steel sheet according to claim 1 , wherein said composition comprises, in weight
0.50%≦C≦0.70%.

12 : A steel sheet according to claim 1 , wherein said composition comprises, in weight
0.70%≦C≦1.05%.

13 : A steel sheet according to claim 10 , wherein said composition comprises, in weight
17%≦Mn≦24%.

14 : A steel sheet according to claim 11 , wherein said composition comprises, in weight
17%≦Mn≦24%.

15 : A steel sheet according to claim 12 , wherein said composition comprises, in
weight 16%≦Mn≦19%.

16 : A steel sheet according to claim 1 , wherein said composition comprises 0.070%≦V≦0.40%, vanadium V p under the form of precipitated carbides, nitrides, carbonitrides, being
0.070%≦V p ≦0.140%.

17 : A steel sheet according to claim 1 , wherein said composition comprises 0.060%≦Ti p ≦0.40%, titanium Ti p under the form of precipitated carbides, nitrides, carbonitrides, being
0.060%≦Ti p ≦0.110%.

18 : A steel sheet according to claim 1 , wherein said composition comprises 0.090%≦Nb≦0.40%, niobium Nb p under the form of precipitated carbides, nitrides, carbonitrides, being
0.090%≦Nb p ≦0.200%.

19 : A steel sheet according to claim 1 , wherein said composition comprises 0.20%≦Mo≦1.8%, molybdenum Mo p under the form of carbides being
0.20%≦Mo p ≦0.35%.

20 : A steel sheet according to claim 1 , wherein the mean size d of said carbides, nitrides, carbonitrides is comprised between 7 and 20 nanometers.

21 : A steel sheet according to claim 1 , wherein at least 75% of the population of said carbides, nitrides, carbonitrides, is located in intragranular position.

22 : A steel sheet according to claim 1 further comprising at least one element chosen among
0.0005%≦B≦0.010%;
Ni≦2%; and
Cu≦5%.

23 : A steel sheet according to claim 4 further comprising at least one element chosen among
0.0005%≦B≦0.010%;
Ni≦2%; and
Cu≦5%.

Assignees

• Arcelormittal France
• Thyssenkrupp Steel Europe Ag

Inventors

• Scott Colin
• Cugy Philippe
• Allely Christian

Classifications

• C21D8/02 Primary

  during manufacturing of plates or strips (C21D8/12 takes precedence) · CPC title

• Y10T428/12799

  Next to Fe-base component [e.g., galvanized] · CPC title

• C21D1/26

  Methods of annealing · CPC title

• C21D6/005

  containing Mn · CPC title

• C23C28/025

  with at least one zinc-based layer · CPC title