Arcelormittal

Usinor

Arcelor France

François Stouvenot

Colin Scott

Emmanuel Lucas

Sebastian Cobo

Philippe Cugy

Marie-Christine Theyssier

Dominique Viale

Marc Burty

Nicolas Guelton

Pascal Gardin

Jean-François Domgin

Raymond Reitz

Frédéric Leclercq

A steel sheet made of a steel having a composition including, C: 0.3-0.4%, Mn: 0.5-1.0%, Si: 0.4-0.8%, Cr: 0.1-1.0%, Mo: 0.1-0.5%, Nb: 0.01-0.1%, Al: 0.01-0.1%, Ti: 0.008-0.03%, B: 0.0005-0.003%, P≤0.020%, Ca≤0.001%, S≤0.004%, N≤0.005% and including optionally Ni<0.5%, having a microstructure including, in surface fraction, from 60% to 95% of ferrite, the rest being martensite-austenite islands, pearlite or bainite, and including a bulk and a skin layer occupying the outermost 10% of the thickness on either sides of the bulk, the skin layer having a skin layer inclusion population wherein the surface fraction of oxides is equal to or below 60*10.

Steel sheet and high strength press hardened steel part and method of manufacturing the same

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.

Method of producing austenitic iron/carbon/manganese steel sheets having very high strength and elongation characteristics and excellent homogeneity

A vacuum treatment of cast metal in liquid form employing the steps of: introducing the cast metal in liquid form into a metallurgic ladle; filling the ladle until a guard height ranging between 0.4 and 0.6 m is reached; and treating the metal while bringing the atmosphere above the ladle under vacuum, and simultaneously stirring the cast metal by injecting helium into the base of the ladle during part of or the whole treatment.

Vacuum treatment of molten metal with simultaneous stirring by helium injection

Growing community of inventors

Labry, France

François Stouvenot