A cold-rolled and heat-treated steel sheet having a microstructure consisting of, in surface fraction: between 10% and 30% of retained austenite, the retained austenite being present as films having an aspect ratio of at least 3 and as Martensite Austenite islands, less than 8% of the Martensite Austenite islands having a size above 0.5 μm, at most 1% of fresh martensite, at most 50% of tempered martensite, and recovered martensite containing precipitates of at least one element chosen among niobium, titanium and vanadium. A method for manufacturing the cold-rolled and heat-treated steel sheet is also described.

A cold-rolled and heat-treated steel sheet having a microstructure consisting of, in surface fraction: between 10% and 30% of retained austenite, the retained austenite being present as films having an aspect ratio of at least 3 and as Martensite Austenite islands, less than 8% of the Martensite Austenite islands having a size above 0.5 μm, at most 1% of fresh martensite, at most 50% of tempered martensite, and recovered martensite containing precipitates of at least one element chosen among niobium, titanium and vanadium. A method for manufacturing the cold-rolled and heat-treated steel sheet is also described.

Fe-Al-based plated hot-stamped member exhibiting excellent formed part corrosion resistance and post-coating corrosion resistance and manufacturing method. The hot-stamping member includes Fe-Al-based plated layer on one or both surfaces of a base material, the base material has a predetermined steel component, Fe-Al-based plated layer has a thickness of 10 μm or more and 60 μm or less, formed by A, B, C and D layers sequentially from a surface toward the base material, and each of the four layers is a Fe-Al-based intermetallic compound containing Al, Fe, Si, Mn and Cr for predetermined contents with the balance made up of impurities, the D layer further contains Kirkendall voids each of which cross-sectional area is 3 μm.sup.2-30 μm.sup.2 for 10 pieces/6000 μm.sup.2 or more and 40 pieces/6000 μm.sup.2 or less.

Provided is a high strength steel sheet that has a predetermined chemical composition and is manufactured under optimum conditions, the high strength steel sheet having a steel microstructure including, by area, ferrite: 30% or more and 80% or less, tempered martensite: 3.0% or more and 35% or less, and retained austenite: 8% or more, wherein the quotient of the area fraction of grains of the retained austenite, the grains having an aspect ratio of 2.0 or more and a minor axis length of 1 μm or less, divided by the total area fraction of the retained austenite is 0.3 or more, wherein the quotient of the average Mn content (mass %) in the retained austenite divided by the average Mn content (mass %) in the ferrite is 1.5 or more.

Provided is a high strength steel sheet that has a predetermined chemical composition and is manufactured under optimum conditions, the high strength steel sheet having a steel microstructure including, by area, ferrite: 30% or more and 80% or less, martensite: 5% or more and 35% or less, and retained austenite: 8% or more, wherein the quotient of the area fraction of grains of the retained austenite, the grains having an aspect ratio of 2.0 or more and a minor axis length of 1 μm or less, divided by the total area fraction of the retained austenite is 0.3 or more, wherein the quotient of the average Mn content (mass %) in the retained austenite divided by the average Mn content (mass %) in the ferrite is 1.5 or more.

A stainless blasting medium is provided including blasting medium elements containing an austenitic chromium-manganese steel, the blasting medium comprising the austenitic chromium-manganese steel-containing blasting medium elements in a range of ≥90 wt.-% to ≤100 wt.-% relative to the total weight of the stainless blasting medium. The following further relates to the use of the stainless blasting medium for blasting surfaces, metal and non-metal surfaces, such as workpieces, in particular stainless workpieces.

This hot-rolled steel sheet has a predetermined chemical composition, in which a microstructure contains, by area %, less than 3.0% of residual austenite, 15.0% or more and less than 60.0% of ferrite, and less than 5.0% of pearlite, has a ratio L.sub.60/L.sub.7 of a length L.sub.60 of a grain boundary having a crystal misorientation of 60° to a length L.sub.7 of a grain boundary having a crystal misorientation of 7° about a<110> direction of less than 0.60, has a standard deviation of a Mn concentration of 0.60 mass % or less, and has a tensile strength of 980 MPa or more.

Thick high-strength steel having a high yield ratio and excellent durability, and a method for manufacturing same are provided. The thick high-strength steel having a high yield ratio and excellent durability of the present invention comprises, in percentage by weight, C: 0.05 to 0.15%, Si: 0.01 to 1.0%, Mn: 1.0 to 2.3%, Al: 0.01 to 0.1%, Cr: 0.005 to 1.0%, P: 0.001 to 0.05%, S: 0.001 to 0.01%, N: 0.001 to 0.01%, Nb: 0.005 to 0.07%, Ti 0.005 to 0.11%, Fe and unavoidable impurities.

The present invention relates to a manganese steel alloy having a heat-treated microstructure comprising: (a) an alloy composition of: manganese: 12 to 30 wt %; carbon: 1.0 to 2.0 wt %; chromium: 4.5 to 7.0 wt %; molybdenum: 0.0 to 3.0 wt %; and iron and impurities: balance, and (b) an austenitic ferrous matrix; and (c) formed refractory particles dispersed throughout the austenitic ferrous matrix such that ≥10% of the formed refractory particles are located within crystallites of the austenitic ferrous matrix, as opposed to being located at grain boundaries between the crystallites, wherein the formed refractory particles are compounds of carbides and/or borides and/or nitrides of any one or more of chromium, zirconium, hafnium, tantalum, molybdenum, and tungsten. The invention further relates to equipment adapted for high-stress gouging abrasion that includes the manganese steel alloy of the invention, and a method of producing the manganese steel alloy of the invention.

The present invention relates to a manganese steel alloy having a heat-treated microstructure comprising: (a) an alloy composition of: manganese: 12 to 30 wt %; carbon: 1.0 to 2.0 wt %; chromium: 4.5 to 7.0 wt %; molybdenum: 0.0 to 3.0 wt %; and iron and impurities: balance, and (b) an austenitic ferrous matrix; and (c) formed refractory particles dispersed throughout the austenitic ferrous matrix such that ≥10% of the formed refractory particles are located within crystallites of the austenitic ferrous matrix, as opposed to being located at grain boundaries between the crystallites, wherein the formed refractory particles are compounds of carbides and/or borides and/or nitrides of any one or more of chromium, zirconium, hafnium, tantalum, molybdenum, and tungsten. The invention further relates to equipment adapted for high-stress gouging abrasion that includes the manganese steel alloy of the invention, and a method of producing the manganese steel alloy of the invention.