The present invention relates to steel sheet realizing both formability and weldability. The steel sheet of the present invention is characterized in that at a surface layer part of a region down to 30 μm from the surface of the steel sheet in the sheet thickness direction, Si oxide grains are present in 3000 to 6000/mm.sup.2 in number density, an average of natural logarithms of the particle sizes of the Si oxide grains measured in m units is −2.0 to −1.2, the standard error of the natural logarithms of the particle sizes is 0.6 or less, and the number of Si oxide grains with deviations of the natural logarithms of the particle sizes from the average larger than 2 times the standard error is 5% or less of the total number of Si oxide grains and at a position of ½ of the thickness of the steel sheet, the number density of the Si oxide grains is 1000/mm.sup.2 or less.

The present disclosure relates to a duplex stainless steel comprising in weight % (wt %): C less than 0.03; Si less than 0.60; Mn 0.40 to 2.00; P less than 0.04; S less than or equal to 0.01; Cr more than 30.00 to 33.00; Ni 6.00 to 10.00; Mo 1.30 to 2.90; N 0.15 to 0.28; Cu 0.60 to 2.20; Al less than 0.05; balance Fe and unavoidable impurities. The present disclosure also relates to a component or a construction material comprising the duplex stainless steel. Additionally, the present disclosure also relates to a process for manufacturing a component comprising said duplex stainless steel.

Provided is a blade material having high strength. The blade material contains, in % by mass, 0.5 to 0.8% of C, 1.0% or less of Si, 1.0% or less of Mn, 11 to 15% of Cr, and 0.1 to 0.8% of V, the remainder includes Fe and inevitable impurities, and has a thickness of 0.5 mm or less, wherein the structure of the blade material as observed after polishing the surface thereof has ferrites and carbides, the carbides have an average particle diameter of 0.5 μm or less, and a proportion of carbides containing V in the carbides is 50% or less in terms of a proportion in an area of a field of view.

There is provided a precipitation hardening stainless steel with the composition: C: 0.05-0.30 wt %, Ni: 9-10 wt %, Mo: 0.5-1.5 wt %, Al: 1.75-3 wt %, Cr: 10.5-13 wt %, V: 0.25-1.5 wt %, Co: 0-0.03 wt %, Mn: 0-0.5 wt %, Si: 0-0.3 wt %, and remaining part up to 100 wt % is Fe and impurity elements, with the additional proviso that the amounts of Al and Ni also fulfil Al=Ni/4±0.5 in wt %. Further Cr.sub.eq is in the interval 11-15.4 wt % and Ni.sub.eq is in the interval 10.5-15 wt %. There is the possibility to have very low amounts of cobalt, well below 0.01 wt %. The precipitation hardening stainless steel displays, low segregation, high yield strength at elevated temperatures, and can also suitably be nitrided. The precipitation hardening stainless steel is more economical to manufacture compared to stainless steel according to the state of the art with the same strength at elevated temperatures.

There is provided a precipitation hardening stainless steel with the composition: C: 0.05-0.30 wt %, Ni: 9-10 wt %, Mo: 0.5-1.5 wt %, Al: 1.75-3 wt %, Cr: 10.5-13 wt %, V: 0.25-1.5 wt %, Co: 0-0.03 wt %, Mn: 0-0.5 wt %, Si: 0-0.3 wt %, and remaining part up to 100 wt % is Fe and impurity elements, with the additional proviso that the amounts of Al and Ni also fulfil Al=Ni/4±0.5 in wt %. Further Cr.sub.eq is in the interval 11-15.4 wt % and Ni.sub.eq is in the interval 10.5-15 wt %. There is the possibility to have very low amounts of cobalt, well below 0.01 wt %. The precipitation hardening stainless steel displays, low segregation, high yield strength at elevated temperatures, and can also suitably be nitrided. The precipitation hardening stainless steel is more economical to manufacture compared to stainless steel according to the state of the art with the same strength at elevated temperatures.

The invention relates to a steel wire suitable for making a spring or medical wire products which remarkably improve the performance of conventional stainless steel wire. The steel comprises (in wt. %): C: 0.02 to 0.15, Si: 0.1 to 0.9, Mn: 0.8 to 1.6, Cr 16 to 20, Ni: 7.5 to 10.5, Mo: ≤3, Al: 0.5 to 2.5, Ti: ≤0.15, N: ≤0.05, optional elements, and impurities, balance Fe, wherein the total amount of Cr and Ni is 25 to 27 wt. %, and wherein the steel has a microstructure including, in volume % (vol. %), martensite: 40 to 90, austenite: 10 to 60, and delta ferrite: ≤5.

The invention describes a two-phase steel comprising 8-12 wt. % Mn, 0.3-0.6 wt. % C, 1-4 wt. % Al, 0.4-1 wt. % V, and a balance of Fe. The steel has martensite and retained austenite phases, and may include vanadium carbide precipitations. A method for making the two-phase steel involves the steps of (a) hot rolling the ingots of the composition to produce a plurality of thick steel sheets, (b) treating the steel sheets by an air cooling process, (c) warm rolling the steel sheets at a temperature in the range of 300-800° C. with a thicknesses reduction of 30-50%, (d) annealing the steel sheets a first time at a temperature in the range of 620-660° C. for 10-300 min, (e) cold rolling the steel sheets at room temperature with a thickness reduction of 10-30% to generate hard martensite, and (f) annealing the steel sheets a second time at a temperature in the range of 300-700° C. for 3-60 min to facilitate the partitioning of carbon and release the residual stress n martensite.

Provided are a chromium-molybdenum steel plate having excellent creep strength and a method for manufacturing same. The chromium-molybdenum steel plate of the present invention comprises, by weight %, 0.11-0.15% of C, 0.10% or less of Si (exclusive of 0%), 0.3-0.6% of Mn, 0.010% or less of S (exclusive of 0%), 0.015% or less of P (exclusive of 0%), 2.0-2.5% of Cr, 0.9-1.1% of Mo, 0.65-1.0% of V, 0.25% or less of Ni (exclusive of 0%), 0.20% or less of Cu (exclusive of 0%), 0.07% or less of Nb (exclusive of 0%), 0.03% or less of Ti (exclusive of 0%), 0.015% or less of N (exclusive of 0%), 0.025% or less of Al (exclusive of 0%), 0.002% or less of B (exclusive of 0%), and the remainder of Fe and unavoidable impurities.

A ripper shank as the impact and wear resistant component is made of a steel of a specific component composition which has a hardness of HRC 53 or more and HRC 57 or less. The steel includes a matrix including a martensite phase and a residual austenite phase, and first nonmetallic particles dispersed in the matrix and including at least one species selected from the group consisting of MnS, TiCN, and NbCN. The steel does not include a M23C6 carbide.

A ripper shank as the impact and wear resistant component is made of a steel of a specific component composition which has a hardness of HRC 53 or more and HRC 57 or less. The steel includes a matrix including a martensite phase and a residual austenite phase, and first nonmetallic particles dispersed in the matrix and including at least one species selected from the group consisting of MnS, TiCN, and NbCN. The steel does not include a M23C6 carbide.