A plastic forming mold made from a stainless steel, having in weight % (wt. %): C 0.32-0.50, Si 0.1-1.0, Mn 0.1-0.8, Cr 11-14, Mo 1.8-2.6, V 0.35-0.70, N 0.05-0.19, optional elements, and a balance of Fe apart from impurities. The stainless steel is hardened and tempered and has a matrix comprising ≥90 vol. % martensite.

A plastic forming mold made from a stainless steel, having in weight % (wt. %): C 0.32-0.50, Si 0.1-1.0, Mn 0.1-0.8, Cr 11-14, Mo 1.8-2.6, V 0.35-0.70, N 0.05-0.19, optional elements, and a balance of Fe apart from impurities. The stainless steel is hardened and tempered and has a matrix comprising ≥90 vol. % martensite.

Provided are: a boron-added high strength steel for bolt excellent in delayed fracture resistance even having a tensile strength of 1100 MPa or more without addition of large amounts of expensive alloy elements such as Cr and Mo: and a high strength bolt made from the boron-added high strength steel for bolt. The high strength steel for bolt contains C of 0.23% to less than 0.40%, Si of 0.23% to 1.50%, Mn of 0.30% to 1.45%, P of 0.03% or less (excluding 0%), S of 0.03% or less (excluding 0%), Cr of 0.05% to 1.5%, V of 0.02% to 0.30%, Ti of 0.02% to 0.1%, B of 0.0003% to 0.0050%, Al of 0.01% to 0.10%, and N of 0.002% to 0.010%, with the remainder being iron and inevitable impurities. The steel has a ratio ([Si]/[C]) of the Si content [Si] to the C content [C] of 1.0 or more and has a ferrite-pearlite mixed microstructure.

Provided are: a boron-added high strength steel for bolt excellent in delayed fracture resistance even having a tensile strength of 1100 MPa or more without addition of large amounts of expensive alloy elements such as Cr and Mo: and a high strength bolt made from the boron-added high strength steel for bolt. The high strength steel for bolt contains C of 0.23% to less than 0.40%, Si of 0.23% to 1.50%, Mn of 0.30% to 1.45%, P of 0.03% or less (excluding 0%), S of 0.03% or less (excluding 0%), Cr of 0.05% to 1.5%, V of 0.02% to 0.30%, Ti of 0.02% to 0.1%, B of 0.0003% to 0.0050%, Al of 0.01% to 0.10%, and N of 0.002% to 0.010%, with the remainder being iron and inevitable impurities. The steel has a ratio ([Si]/[C]) of the Si content [Si] to the C content [C] of 1.0 or more and has a ferrite-pearlite mixed microstructure.

Disclosed is a mar aging steel containing, in combination in mass percent, C in a content from greater than 0% to 0.02%, Mn in a content from greater than 0% to 0.3%, Si in a content from greater than 0% to 0.3%, Ni in a content of 10% to 13%, Mo in a content of 0.5% to 3.5%, Co in a content of 9% to 12%, Cr in a content of 1.5% to 4.5%, Ti in a content of 1.5% to 4.5%, and Al in a content of 0.01% to 0.2%, where the total content of Mo and Ti is 5.0 mass percent or less, and the ratio ([Mo]/[Ti]) of the Mo content [Mo] to the Ti content [Ti] is 1.0 or less, with the remainder consisting of iron and inevitable impurities.

A method of manufacturing an energy absorbing component for a vehicle is provided. The method includes heating a bainitic GENS steel material which has a microstructure including ferrite and bainite to a temperature above the Ac3 temperature to convert a portion of the ferrite and bainite to austenite. The method further includes forming while cooling the heated steel blank into a component in a temperature controlled steel die. During the cooling step, the steel material is cooled to a temperature below the Ms temperature to form retained austenite. A portion of the austenite transforms to martensite and bainite during the forming and cooling step. The method can further include heating the component to a temperature above the Ms temperature after the forming and cooling step to increase energy absorption characteristics. During a crash event, the strain imposed on the component converts retained austenite present in the component to martensite.

The present disclosure is directed and formulations and methods to provide alloys having relative high strength and ductility. The alloys may be provided in seamless tubular form and characterized by their particular alloy chemistries and identifiable crystalline grain size morphology. The alloys are such that they include boride pinning phases. In what is termed a Class 1 Steel the alloys indicate tensile strengths of 700 MPa to 1400 MPa and elongations of 10-70%. Class 2 Steel indicates tensile strengths of 800 MPa to 1800 MPa and elongations of 5-65%. Class 3 Steel indicates tensile strengths of 1000 MPa to 2000 MPa and elongations of 0.5-15%.

The invention concerns a method for heat treatment of an austenitic steel of the High Nitrogen Steel or austenitic HNS type, or of an austenitic steel of the High Interstitial Steel or austenitic HIS type, said austenitic HNS or austenitic HIS containing precipitates of nitrides, carbides or carbonitrides of chromium and/or of molybdenum, this method comprising the step which consists, after machining the austenitic HNS or austenitic HIS containing the precipitates, in redissolving the precipitates by bringing the austenitic HNS or austenitic HIS to its austenitizing temperature, then cooling the austenitic HNS or austenitic HIS sufficiently rapidly to avoid the re-formation of precipitates.

The invention also concerns different heat treatment methods allowing chromium and/or molybdenum nitride, carbide or carbonitride type precipitates to appear in an austenitic HNS or austenitic HIS. Indeed, the presence of these precipitates in the matrix of the austenitic HNS or austenitic HIS makes machining operations easier by promoting the formation and removal of chips during machining of the components.

A high-hardness martensitic stainless steel with excellent antibacterial property and a preparation method therefor are disclosed. The high-hardness martensitic stainless steel with excellent antibacterial property comprises: 0.45-0.65 wt % of C; 0.02-0.06 wt % of N; 0.1-0.6 wt % of Si; 0.3-1.0 wt % of Mn; 0.1-0.4 wt % of Ni; 13-14.5 wt % of Cr; 0.4-0.6 wt % of Mo; 0.8-1.2 wt % of W; 1.5-2.0 wt % of Cu; and the balance of Fe and inevitable impurities. According to the present disclosure, there is an advantage enabling the preparation of the martensitic stainless steel for knives, the martensitic stainless steel having high hardness, high corrosion resistance and excellent antibacterial property, by uniformly distributing fine chromium carbide and e-Cu precipitates in the microstructure of a batch annealed material of a high-carbon martensitic stainless steel containing Cu. In addition, there is an advantage of causing no rust formation on a material after an antibacterial evaluation.

Disclosed is a steel composition including specified ranges of Ni; Mo; Co; Mo+Co+Si+Mn+Cu+W+V+Nb+Zr+Ta+Cr+C; Co+Mo; Ni+Co+Mo; and traces of Al; Ti; N; Si; Mn; C; S; P; B; H; O; Cr; Cu; W; Zr; Ca; Mg; Nb; V; and Ta in specified ranges; the remainder being iron and impurities. The inclusion population, as observed by image analysis over a polished surface measuring 650 mm.sup.2 if hot-formed or hot-rolled; and measuring 800 mm.sup.2 if cold-rolled, does not contain non-metallic inclusions of diameter >10 μm, and, in the case of a hot-rolled sheet, does not contain more than four non-metallic inclusions of diameter 5-10 μm over 100 mm.sup.2, the observation being performed by image analysis over a polished surface measuring 650 mm.sup.2.