Austenitic stainless steel

Abstract

The invention relates to an austenitic high-manganese stainless steel having high strength and ductility. The stainless steel which has in weight % 0.03-0.1% carbon, 0.08-1.0% silicon, 14-26% manganese, 10.5-18% chromium, less than 0.8% nickel, 0.05-0.60% copper, 0.1-0.8% nitrogen and 0.0008-0.0050% boron, with the rest being iron and inevitable impurities occurred in stainless steels, and the stainless steel is cold deformable utilizing the TWIP (TWinning Induced Plasticity) mechanism.

1 . Austenitic high-manganese stainless steel having high strength and ductility, characterized in that the stainless steel which consists of in weight % 0.03-0.1% carbon, 0.08-1.0% silicon, 17.5-26.0% manganese, 10.5-18% chromium, less than 0.8% nickel, 0.05-0.6% copper, 0.1-0.8% nitrogen 0.0008-0.005% boron, 0.001-0.02% titanium and less than 0.04% aluminium, the rest being iron and inevitable impurities occurred in stainless steels, and in that at an annealed state characterize by a yield strength R p0.2  of 470-600 MPa for R p0.2  a tensile strength R m  of 800-930 MPa for R m  and an elongation to fracture A 80 , of 40-60% for A 80  and is cold deformable utilizing a TWIP (TWinning Induced Plasticity) mechanism so that a work-hardening rate based on the cold deformation for the yield strength R p0.2  is at least 20% when the a cold deformation degree is 10%. 
     
     
         2 .- 15 . (canceled) 
     
     
         16 . Austenitic high-manganese stainless steel according to the  claim 1 , characterized in that the work-hardening rate based on the cold deformation for the yield strength R p0.2  is at least 40% when the cold deformation degree is 20%. 
     
     
         17 . Austenitic high-manganese stainless steel according to  claim 1 , characterized in that elongation to fracture A 80  is 25-35% when the cold deformation degree is 10%. 
     
     
         18 . Austenitic high-manganese stainless steel according to  claim 1 , characterized in that elongation to fracture A 80  is 10-20% when the cold deformation degree is 20%. 
     
     
         19 . Austenitic high-manganese stainless steel according to  claim 1 , characterized in that the manganese content is at the range of 19-23%. 
     
     
         20 . Austenitic high-manganese stainless steel according to  claim 1 , characterized in that the chromium content is at the range of 12-16.0%. 
     
     
         21 . Austenitic high-manganese stainless steel according to  claim 1 , characterized in that the chromium content is at the range of 12.5-14%. 
     
     
         22 . Austenitic high-manganese stainless steel according to  claim 1 , characterized in that the copper content is at the range 0.3-0.6% 
     
     
         23 . Austenitic high-manganese stainless steel according to any  claim 1 , characterized in that the stainless steel is cold deformable for the TWIP effect in the state of as a strip annealed after hot working. 
     
     
         24 . Austenitic high-manganese stainless steel according to  claim 1 , characterized in that the stainless steel is cold deformable for the TWIP effect in the state of as a strip annealed after cold working. 
     
     
         25 . Austenitic high-manganese stainless steel according to  claim 1 , characterized in that the stainless steel is cold deformable for the TWIP effect in the state of as a strip annealed after hot working and cold working and then cold deformed. 
     
     
         26 . Austenitic high-manganese stainless steel according to  claim 1 , characterized in that the austenitic stainless steel may be manufactured as slabs; blooms; billets; flat products such as coils, strips, plates, sheets; long products such as bars, rods, wires, profiles and shapes; or tubular products such as pipes and tubes. 
     
     
         27 . Austenitic high-manganese stainless steel according to any of the preceding claims, characterized in that the austenitic stainless steel is applied in automotive construction, in tanks, in crash relevant parts, in construction or in rail vehicles.