A lumen stent preform is provided using a plasma nitriding technology, a preparation method thereof, a method for preparing a lumen stent by using the preform, and a lumen stent obtained according to the method. The preform is manufactured by using pure iron or an iron alloy containing no strong nitrogen compound, has a hardness of 160-250HV0.05/10, and has a microstructure that is a deformed structure having a grain size scale greater than or equal to 9 or a deformed structure after cold machining. Alternatively, the preform is an iron alloy containing a strong nitrogen compound, and has a microstructure that is a deformed structure having a grain size scale greater than or equal to 9 or a deformed structure after cold machining. The lumen stem preform meets the requirements of a conventional stent for radial strength and plasticity, so that plasma nitriding is applicable to commercial preparation of a lumen stent.

A lumen stent preform is provided using a plasma nitriding technology, a preparation method thereof, a method for preparing a lumen stent by using the preform, and a lumen stent obtained according to the method. The preform is manufactured by using pure iron or an iron alloy containing no strong nitrogen compound, has a hardness of 160-250HV0.05/10, and has a microstructure that is a deformed structure having a grain size scale greater than or equal to 9 or a deformed structure after cold machining. Alternatively, the preform is an iron alloy containing a strong nitrogen compound, and has a microstructure that is a deformed structure having a grain size scale greater than or equal to 9 or a deformed structure after cold machining. The lumen stem preform meets the requirements of a conventional stent for radial strength and plasticity, so that plasma nitriding is applicable to commercial preparation of a lumen stent.

A workpiece made from a self passivating metal and having one or more surface regions defining a Beilby layer as a result of a previous metal shaping operation is activated for subsequent low temperature gas hardening by exposing the workpiece to the vapors produced by heating an oxygen-free nitrogen halide salt.

A workpiece made from a self passivating metal and having one or more surface regions defining a Beilby layer as a result of a previous metal shaping operation is activated for subsequent low temperature gas hardening by exposing the workpiece to the vapors produced by heating an oxygen-free nitrogen halide salt.

A method for manufacturing a metal ring laminate includes: performing an aging treatment on a metal ring laminate in which a plurality of metal rings made of maraging steel are laminated; and performing a nitriding treatment on the metal ring laminate that has been nitrided. Oxidizing treatment is performed after the aging treatment but before the nitriding treatment at a temperature equal to or higher than 350° C. and lower than an aging treatment temperature.

An antimicrobial and adhesion-proof titanium tableware and a manufacturing method of the same are provided. The antimicrobial and adhesion-proof titanium tableware is made of a titanium substrate, and includes a contact portion and an oxidation layer structure. The contact portion is used for contacting foods, food ingredients, drinking water, beverages, or body parts of a user. The oxidation layer structure is formed on one part of a surface of the titanium substrate corresponding to the contact portion. The titanium substrate is made of titanium in α phase, and the oxidation layer structure is a titanium dioxide film in a rutile crystalline form. The oxidation layer structure has a roughened surface and an oxygen diffusion layer formed at an interface of the oxidation layer structure and the titanium substrate.

An antimicrobial and adhesion-proof titanium tableware and a manufacturing method of the same are provided. The antimicrobial and adhesion-proof titanium tableware is made of a titanium substrate, and includes a contact portion and an oxidation layer structure. The contact portion is used for contacting foods, food ingredients, drinking water, beverages, or body parts of a user. The oxidation layer structure is formed on one part of a surface of the titanium substrate corresponding to the contact portion. The titanium substrate is made of titanium in α phase, and the oxidation layer structure is a titanium dioxide film in a rutile crystalline form. The oxidation layer structure has a roughened surface and an oxygen diffusion layer formed at an interface of the oxidation layer structure and the titanium substrate.

A grain oriented electrical steel sheet includes: a base steel sheet; a lower layer which is arranged in contact with the base steel sheet; and an insulation coating which is arranged in contact with the lower layer and which includes a phosphate and a colloidal silica as main components. The base steel sheet includes the predetermined chemical composition and includes a B compound whose major axis length is 1 to 20 μm and whose number density is 1×10 to 1×10.sup.6 pieces/mm.sup.3. The lower layer is a glass film which includes a forsterite as main component or an intermediate layer includes a silicon oxide as main component.

A grain oriented electrical steel sheet includes: a base steel sheet; a glass film which is arranged in contact with the base steel sheet; and an insulation coating which is arranged in contact with the glass film and which includes a phosphate and a colloidal silica as main components. The base steel sheet includes the predetermined chemical composition. A BN whose average particle size is 50 to 300 nm is included at a predetermined number density in a region which is from an interface between the glass film and the insulation coating till 5 μm toward the base steel sheet in a depth direction. A B emission intensity obtained inside the glass film is more than a B emission intensity obtained inside the base steel sheet, when a B emission intensity is measured from a surface of the insulation coating by a glow discharge emission spectroscopy.

There is provided a precipitation hardening steel with the composition: C: 0.05-0.30 wt %, Ni: 3-9 wt %, Mo: 0.5-1.5 wt %, Al: 1-3 wt %, Cr: 2-14 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/3±0.5 in wt %. There is the possibility to have very low amounts of cobalt, well below 0.01 wt %. The precipitation hardening steel displays, low segregation, high yield strength at elevated temperatures, high resistance against corrosion, and can also suitably be nitrided. The precipitation hardening steel is more economical to manufacture compared to steel according to the state of the art with the same strength at elevated temperatures.