A TWIP steel sheet is provided having an austenitic matrix including by weight: 0.1C1.2%, 13.0Mn<25.0%, 0.1Si3.0%, 0.1Cu5.0%, S0.030%, P0.080%, N0.1%, 0.1Al4.0% and 0.1V2.50% in such way that:when the amount of Al<2.0%, the weight ratio Al/V is between 0.2 and 8 orwhen the amount of Al2.0%, the amount of V>0.25%, and on a purely optional basis, one or more of Nb0.5%, B0.005%, Cr1.0%, Mo0.40%, Ni1.0%, Ti0.5%, and/or 0.06Sn0.2%, the remainder of the composition being made of iron and inevitable impurities resulting from elaboration.

A method for the manufacture of a cold rolled, recovered TWIP steel sheet coated with a metallic coating is provided including the following steps: (A) the feeding of a slab having the following composition : 0.1<C<1.2%, 13.0Mn<25.0%, S0.030%, P0.080%, N0.1%, Si3.0%, and on a purely optional basis, one or more elements such as Nb0.5%, B0.005%, Cr1.0%, Mo0.40%, Ni1.0%, Cu5.0%, Ti0.5%, V2.5%, Al4.0%, 0.06Sn0.2%, the remainder of the composition making up of iron and inevitable impurities resulting from elaboration; (B) Reheating such slab and hot rolling it; (C) A coiling step; (D) A first cold-rolling; (E) A recrystallization annealing; (F) A second cold-rolling; and (G) A recovery heat treatment performed by hot-dip coating.

A method for manufacturing a recovered steel sheet having an austenitic matrix presenting at least one mechanical property (M) equal or above a target value M.sub.target is provided. The method includes a calibrating process involving heat on at least 2 samples of the steel, corresponding to Pareq values P, submitting said samples to X-ray diffraction so as to obtain spectrums including a main peak whose width at mid height FWHM is being measured, measuring a mechanical property (M) of said samples, measuring a recovery or recrystallization state of each sample, drawing a curve of M as a function of FWMH in a domain where the samples are recovered from 0 to 100%, but not recrystallized. The method further includes calculating a FWHM.sub.target corresponding to a target mechanical property M.sub.target, determining a pareq value P.sub.target of the heat treatment to perform to reach M.sub.target and selecting a time t.sub.target and a temperature T.sub.target corresponding to the P.sub.target value. The method further includes feeding a recrystallized steel sheet having a M.sub.recrystallization, cold-rolling the recrystallized steel sheet in order to obtain a steel sheet having a M.sub.cold-roll and annealing the cold rolled steel sheet at a temperature T.sub.target during a time t.sub.target.

A steel product includes the following chemical composition in wt. %: C: 0.01 to <0.3, Mn: 4 to <10, Al: 0.003 to 2.9, Mo: 0.01 to 0.8, Si: 0.02 to 0.8, Ni: 0.005 to 3, P: <0.04, S: <0.02, N: <0.02, with the remainder being iron including unavoidable steel-associated elements, wherein an alloy composition satisfies the equation 6<1.5 Mn+Ni<8; or the equation 0.11<C+Al<3, or an alloy composition contains, in addition to Ni, at least one or more of the elements, in wt. %, B: 0.0005 to 0.014; V: 0.006 to 0.1; Nb: 0.003 to 0.1; Co: 0.003 to 3; W: 0.03 to 2 or Zr: 0.03 to 1. The steel product has a microstructure of 2 to 90 vol. % austenite, less than 40 vol. % ferrite and/or bainite, with the remainder being martensite.

The invention relates to a method for producing a flat steel product made of a medium manganese steel having a TRIP/TWIP effect. The aim of the invention is to achieve an improvement in the yield strength when a sufficient residual deformability of the produced flat steel product is obtained. This aim is achieved by the following steps: cold rolling a hot or cold strip, annealing the cold-rolled hot or cold strip at 500 to 840 C. for 1 minute to 24 hours, temper rolling or finishing the annealed hot or cold strip to form a flat steel product having a degree of deformability between 0.3% and 60%. The invention further relates to a flat steel product produced according to said method and to a use thereof.

Medical instruments, particularly, endodontic instruments with unique limited memory characteristics, and methods for making such instruments. One embodiment includes heat treating an endodontic blank prior to forming a working portion of the endodontic instrument.

Disclosed herein are new face-centered cubic (f.c.c.) high-entropy alloys with compositions (in atomic %) of Fe.sub.aNi.sub.bMn.sub.cAl.sub.dCr.sub.eC.sub.f where a is between 37-43 atomic %, b is between 8-14 atomic %, c is between 32-38 atomic %, d is 4.5-10.5 atomic %, e is between 2.5-9 atomic % and f is between 0-2 atomic %. The undoped alloy has strength of 159 MPa and 40% elongation to failure, but the doped, carbon-containing alloy having 1.1 atomic percent carbon has yield strength of 360 MPa, an ultimate tensile strength (UTS) of 1200 MPa and 50% elongation to failure at room temperature. At 700 C., the yield strength is 214 MPa with 24% elongation to failure. Thus, the present alloy may replace austenitic stainless steels in applications where better strength is needed at both room temperature and elevated temperature in an oxidation resistant alloy.

Methods for modifying a physical characteristic of finished endodontic instruments made from one or more superelastic alloys is described which include heat treating one or more finished endodontic instruments in a salt bath for a specific time (e.g., from about four hours to about six hours), at a specified temperature (e.g., from about 475 C. to about 550 C.), and preferably at a specified pH range.

A lean duplex stainless steel and a method of manufacturing the same are disclosed. A lean duplex stainless steel according to an embodiment of the present invention comprises, by weight percent, 0.05 to 0.1% of carbon (C), 2.0 to 4.0% of silicon (Si), 4.0 to 8.0% of manganese (Mn), 13.0 to 15.0% of chromium (Cr), 0.05 to 0.15% of nitrogen (N), with the remainder being iron (Fe) and other unavoidable impurities. Therefore, it is possible to minimize the manufacturing costs by minimizing or excluding the alloy components of Cr, Ni, Mo, and the like. in the component system of the duplex stainless steel, to secure an elongation of 30% or more and to secure a corrosion resistance level of 400 series general steel.

A method for manufacturing a recovered steel sheet having an austenitic matrix presenting at least one mechanical property (M) equal or above a target value M.sub.target is provided. The method includes a calibrating process involving heat treatments on at least 2 samples of the steel, corresponding to Pareq values P, submitting said samples to X-ray diffraction so as to obtain spectrums including a main peak whose width at mid height FWHM is being measured, measuring a mechanical property (M) of said samples, measuring a recovery or recrystallization state of each sample, drawing a curve of M as a function of FWMH in a domain where the samples are recovered from 0 to 100%, but not recrystallized. The method further includes calculating a FWHM.sub.target corresponding to a target mechanical property M.sub.target, determining a pareq value P.sub.target of the heat treatment to perform to reach M.sub.target and selecting a time t.sub.target and a temperature T.sub.target corresponding to the P.sub.target value. The method further includes feeding a recrystallized steel sheet having a M.sub.recrystallization, cold-rolling the recrystallized steel sheet in order to obtain a steel sheet having a M.sub.cold-roll and annealing the cold rolled steel sheet at a temperature T.sub.target during a time t.sub.target.