A high permeability grain oriented electrical steel having a chemistry comprising, all in weight percent, 2.5% to 4.5% silicon, 0.02% to 0.08% carbon, 0.01 to 0.05% aluminum, 0.005% to 0.050% sulfur or selenium, 0.02 to 0.20% manganese, 0.05 to 0.20% tin, 0.05 to 1% copper, 0.5% to 2.0% chromium, up to 0.10% phosphorus and up to 0.20% antimony with the balance being essentially iron and residual elements. The steel contains chromium and phosphorus in such amounts that a Cr:(P+0.25Sb) ratio is below 80:1 or, below 50:1, or below 30:1 which provides highly stable magnetic properties in the finished steel sheet. A hot processed band comprised of such steel is annealed and rapidly cooled after such annealing at a rate of at least 50° C. per second from 875-950° C. to a temperature below 400° C. prior to cold rolling to final thickness. Such steel forming a hot processed band having a thickness of from 1.5 to 4.0 mm and having a volume resistivity of at least 50 μΩ-cm, an austenite volume fraction (γ1150° C.) of at least 20%, and an isomorphic layer thickness of at least 2% of the total thickness on at least one surface of the hot processed band.

High strength precipitation hardening stainless steel alloy is disclosed. The steel alloy has a composition by weight %, about: 30.0% max nickel (Ni), 0.0 to 15.0% cobalt (Co), 25.0% max chromium (Cr), 5.0% max molybdenum (Mo), 5.0% max titanium (Ti), 5.0% max vanadium (V), about 0.5% max lanthanum (La) and/or cerium (Ce), and in balance iron (Fe) and inevitable impurities. The steel alloy provides a unique combination of corrosion resistance, strength and toughness and is a material for aircraft landing gears and structures.

An austenitic stainless steel having excellent processability and surface characteristics and a method of manufacturing the austenitic stainless steel are disclosed. The austenitic stainless steel includes, by weight %, 0.005% to 0.15% of carbon (C), 0.1% to 1.0% of silicon (Si), 0.1% to 2.0% of manganese (Mn), 6.0% to 10.5% of nickel (Ni), 16% to 20% of chromium (Cr), 0.005% to 0.2% of nitrogen (N), the remainder iron (Fe) and other unavoidable impurities, wherein a degree of Ni surface negative segregation defined by the following Formula (1) is in a range of 0.6 to 0.9.
(C.sub.Ni-Min)/(C.sub.Ni-Ave)  Formula (1), where C.sub.Ni-Min is a minimum concentration of Ni on the surface of the austenitic stainless steel and C.sub.Ni-Ave is an average concentration of Ni on the surface of the austenitic stainless steel.

The present disclosure discloses a 690 MPa high-strength medium-manganese steel with low yield ratio and medium thickness and a manufacture method thereof, which relates to the technical field of steel smelting. The 690 MPa high-strength medium-manganese steel with low yield ratio and medium thickness is composed of the following chemical composition in mass percentage: C: 0.05%-0.10%, Mn: 4.1%-4.7%, Si: 0.15%-0.4%, P≤0.010%, S≤0.003%, Ti: 0.01%-0.05%, Ni+Cr+Mo≤0.6%, and the balance of Fe and unavoidable impurities. The steel plate manufactured meets the safety performance and construction cost requirements of the construction machinery on the ultra-high-strength steel in complex environments.

A seamless steel pipe of the present invention is a seamless steel pipe having a composition that includes, in mass %, C: 0.02 to 0.12%, Si: 0.010 to 1.00%, Mn: 0.10 to 2.00%, P: 0.050% or less, S: 0.004% or less, Al: 0.010 to 0.100%, Cu: 0.03 to 0.80%, Ni: 0.02 to 0.50%, Cr: 0.55 to 1.00%, Sb: 0.005 to 0.20%, and the balance Fe and incidental impurities, and satisfying the following formula (1),

1.7×Cu*+11×Cr*+3.8×Sb*≥13.5   (1), where Cu*, Cr*, and Sb* represent average concentrations of Cu, Cr, and Sb, respectively, in mass %, as measured in a region 0.5 to 2.0 mm away from an outer surface of the steel pipe, the seamless steel pipe having a yield strength of 230 MPa or more, and a tensile strength of 380 MPa or more.

An alloy material is provided that has a chemical composition consisting of, in mass %, C: 0.030% or less, Si: 0.01 to 1.0%, Mn: 0.01 to 2.0%, P: 0.030% or less, S: 0.0050% or less, Cr: 28.0 to 40.0%, Ni: 32.0 to 55.0%, sol. Al: 0.010 to 0.30%, N: more than 0.30% and not more than 0.000214×Ni.sup.2−0.03012×Ni+0.00215×Cr.sup.2−0.08567×Cr+1.927, O: 0.010% or less, Mo: 0 to 6.0%, W: 0 to 12.0%, Ca: 0 to 0.010%, Mg: 0 to 0.010%, V: 0 to 0.50%, Ti: 0 to 0.50%, Nb: 0 to 0.50%, Co: 0 to 2.0%, Cu: 0 to 2.0%, REM: 0 to 0.10%, and the balance: Fe and impurities, and in which Fn1=Mo+(½)W is 1.0 to 6.0, and a yield strength at a 0.2% proof stress is 1103 MPa or more.

A stainless steel material including a base material made of ferritic stainless steel, a Cr oxide layer formed on a surface of the base material, and a spinel oxide layer formed on a surface of the Cr oxide layer, wherein a chemical composition of the base material satisfies [16.0≤Cr+3×Mo−2.5×B−17×C−3−Si≤35.0], a thickness of the Cr oxide layer (T.sub.Cr) and a thickness of the spinel oxide layer (T.sub.S) satisfy [0.55≤T.sub.Cr/T.sub.S≤6.7], the base material contains precipitate including one or more kinds selected from a M.sub.23C.sub.6, a M.sub.2B, a complex precipitate in which M.sub.2B acts as a precipitation nucleus, and M.sub.23C.sub.6 precipitates on a surface of the M.sub.2B, and a complex precipitate in which NbC acts as a precipitation nucleus, and M.sub.23C.sub.6 precipitates on a surface of the NbC, and a part of the precipitate protrude from the surface of the Cr oxide layer.

A duplex stainless steel has reduced precipitation risks of Al nitride and Cr nitride which are undesirable precipitates, and has superior low temperature toughness. The duplex stainless steel has in mass %, indicated as “%”, C: 0.001 to 0.030%, Si: 0.05 to 0.5%, S: not more than 0.002%, Ni: 6 to 7.5%, Cr: 23 to 26%, Mo: 2 to 4.0%, N: 0.20 to 0.40%, Al: 0.005 to 0.03%, Mn: 0.05 to 0.3%, B: 0.0001 to 0.0050% and Fe, and the remainder being inevitable impurities. The duplex stainless steel has an impact value of not less than 87.5 J/cm.sup.2 at −46±2° C. as defined in Japanese Industrial Standards Z2242.

A steel for forging mechanical parts including the following elements, expressed in percentage by weight 0.2%≤C≤0.5%; 0.8%≤Mn≤1.5% ; 0.4%≤Si≤1%; 0.15%≤V≤0.6%; 0.01%≤Nb≤0.15%; 0.01%≤Cr≤0.5%; 0.01%≤P≤0.05%; 0.04%≤S≤0.09%; 0.01%≤N≤0.025%; and can contain one or more of the following optional elements 0%≤Al≤0.05%; 0%≤Mo≤0.5%; 0.01%≤Ni≤0.5%; 0%≤Ti≤0.2%; 0%≤B≤0.008%; 0%≤Cu≤0.5%; the remainder composition being composed of iron and unavoidable impurities caused by processing, the microstructure of said steel comprising 50% to 90% of Pearlite, 10% to 40% of Ferrite, with an optional presence of acicular ferrite between 0% and 2%, a niobium equivalent of 80% or more.

Disclosed is an austenitic stainless steel having an increased yield ratio. The disclosed austenitic stainless steel is characterized by comprising, in percent by weight (wt %), 0.1% or less (exclusive of 0) of C, 0.2% or less (exclusive of 0) of N, 1.5 to 2.5% of Si, 6.0 to 10.0% of Mn, 15.0 to 17.0% of Cr, 0.3% or less (exclusive of 0) of Ni, 2.0 to 3.0% of Cu, and the remainder of Fe and other inevitable impurities, and satisfying Expressions (1) and (2) below.

3.2≤5.53+1.4Ni−0.16Cr+17.1(C+N)+0.722Mn+1.4Cu−5.59Si≤7  Expression (1):

551-462(C+N)−9.2Si−8.1Mn−13.7Cr−29(Ni+Cu)≤110  Expression (2): wherein C, N, Si, Mn, Cr, Ni, and Cu indicate the content (wt %) of respective elements.