Arcelormittal

Thyssenkrupp Steel Europe Ag

Arcelormittal France

Arcelor France

Thyssenkrupp Steel Ag

Arcelormittal Investigacion Y Desarrollo, S.l.

Philippe Cugy

Colin Scott

Christian Allely

Marie-Christine Theyssier

Nicolas Guelton

François Stouvenot

Anne Dez

Maurita Roscini

Dominique Cornette

A hot-rolled or cold-rolled steel plate having a composition including, in weight percent: 0.6%&#x2264;C&#x2264;0.9%; 17%&#x2264;Mn&#x2264;22%; 0.2%&#x2264;Al&#x2264;0.9%; 0.2%&#x2264;Si&#x2264;1.1%; with 0.85%&#x2264;Al+Si&#x2264;1.6%; 1.2%&#x2264;Cu&#x2264;1.7%; S&#x2264;0.030%; P&#x2264;0.080%; N&#x2264;0.1%; 0&#x3c;Nb&#x2264;0.25%; 0&#x3c;V&#x2264;0.5%; 0&#x3c;Ti&#x2264;0.5%; 0&#x3c;Ni&#x2264;2%; trace amounts &#x2264;Cr&#x2264;2% and B&#x2264;0.010% is provided. A remainder of the composition includes iron and impurities resulting from production of the steel plate. A method for manufacturing a steel plate and use of the steel plate in the automotive industry is also provided.

Hot-rolled or cold-rolled steel plate

An austenitic steel sheet excellent in resistance to delayed cracking is provided. The composition of said steel comprises in weight: 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: 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: 

Iron-carbon-manganese austenitic steel sheet

A process for fabricating a steel sheet is provided. The process includes soaking a steel sheet. The steel has a composition including iron, carbon, manganese, silicon, aluminum, sulfur, phosphorus and nitrogen and at least one metallic element X chosen among vanadium, titanium, niobium, molybdenum, and chromium. A quantity Xof metallic element under the form of carbides, nitrides or carbonitrides is, by weight:0.030%&#x2264;V&#x2264;0.40%;0.030%&#x2264;Ti&#x2264;0.50%;0.040%&#x2264;Nb&#x2264;0.40%;0.14%&#x2264;Mo&#x2264;0.44%; or0.070%&#x2264;Cr&#x2264;0.6%.The soaking step occurs under a pure nitrogen or argon atmosphere with a dew point lower than &#x2212;30&#xb0; C. at a soaking temperature &#x3b8; between 250 and 900&#xb0; C. and with a dynamic circulation of a regenerated atmosphere.

Process for manufacturing iron-carbon-maganese austenitic steel sheet with excellent resistance to delayed cracking

An austenitic steel sheet excellent in resistance to delayed cracking, the composition of said steel comprising, in weight: 0,35%&#x3c;C&#x3c;1,05%, 15%&#x3c;Mn&#x3c;26%, Si&#x3c;3%, Al&#x3c;0,050%, S&#x3c;0,030%, P&#x3c;0,080%, N&#x3c;0,1%, at least one metallic element X chosen among vanadium, titanium, niobium, molybdenum, chromium: 0,050%&#x3c;V&#x3c;0,50%, 0,040%&#x2266;Ti&#x3c;0,50%, 0,070%&#x3c;Nb&#x3c;0,50%, 0,14%&#x3c;Mo&#x3c;2%, 0,070%&#x3c;Cr&#x3c;2% and optionally, one or several elements chosen among 0,0005%&#x3c;B&#x3c;0,010%, Ni&#x3c;2%, Cu&#x3c;5%, the remainder being iron and unavoidable impurities inherent to fabrication, including hydrogen, the quantity Xp of said at least one metallic element under the form of carbides, nitrides or carbonitrides being, in weight: 0,030%&#x3c;VP&#x3c;0,40%, 0,030%&#x3c;Tip&#x3c;0,50%, 0,040%&#x3c;Nbp&#x3c;0,40%, 0,14%&#x3c;Mop&#x3c;0,44%, 0,070%&#x3c;Crp&#x3c;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, being such that (I) &#x3c;3,3. 

Process for manufacturing iron-carbon-manganese austenitic steel sheet with excellent resistance to delayed cracking, and sheet thus produced

Iron-carbon-manganese austenitic steel sheet, the chemical composition of which comprises, the contents being expressed by weight: 0.45%&#x2266;C&#x2266;0.75%; 15%&#x2266;Mn&#x2266;26%; Si&#x2266;3%; Al&#x2266;0.050%; S&#x2266;0.030%; P&#x2266;0.080%; N&#x2266;0.1%; at least one metal element chosen from vanadium, titanium, niobium, chromium and molybdenum, where 0.050%&#x2266;V&#x2266;0.50%; 0.040%&#x2266;Ti&#x2266;0.50; 0.070%&#x2266;Nb&#x2266;0.50%; 0.070%&#x2266;Cr&#x2266;2%; 0.14%&#x2266;Mo&#x2266;2%; and, optionally, one or more elements chosen from 0.0005%&#x2266;B&#x2266;0.003%; Ni&#x2266;1%; Cu&#x2266;5%, the balance of the composition consisting of iron and inevitable impurities resulting from the smelting, the amounts of said at least one metal element in the form of precipitated carbides, nitrides or carbonitrides being: 0.030%&#x2266;V&#x2266;0.150%; 0.030%&#x2266;Ti&#x2266;0.130%; 0.040%&#x2266;Nb&#x2266;0.220%; 0.070%&#x2266;Cr&#x2266;0.6%; 0.14%&#x2266;Mo&#x2266;0.44%.

Method for producing austenitic iron-carbon-manganese metal sheets, and sheets produced thereby

A hot-rolled austenitic iron/carbon/manganese steel sheet, the strength of which is greater than 1200 MPa, the product P (strength (in MPa)&#xd7;elongation at break (in %)) of which is greater than 65 000 MPa % and the nominal chemical composition of which comprises, the contents being expressed by weight: 0.85%&#x2266;C&#x2266;1.05%; 16%&#x2266;Mn&#x2266;19%; Si&#x2266;2%; Al&#x2266;0.050%; S&#x2266;0.030%; P&#x2266;0.050%; N&#x2266;0.1%, and, optionally, one or more elements chosen from: Cr&#x2266;1%; Mo&#x2266;0.40%; Ni&#x2266;1%; Cu&#x2266;5%; Ti&#x2266;0.50%; Nb&#x2266;0.50%; V&#x2266;0.50%, the rest of the composition consisting of iron and inevitable impurities resulting from the smelting, the recrystallized surface fraction of said steel being equal to 100%, the surface fraction of precipitated carbides of said steel being equal to 0% and the mean grain size of said steel being less than or equal to 10 microns.

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Thionville, France

Philippe Cugy