A method for thermochemically treating a part while masking a portion and corresponding mask are provided. The method includes the steps of providing a mask comprising a body with a seat, at least a deformable sealing washer located in the seat, and a tightening bushing, the body having a cavity, placing a first portion of the part in the cavity, a second portion of the part being located in a passage in the sealing washer, and a third portion of the part being located outside the mask, moving the tightening bushing to its tightened position so that the sealing washer is deformed and applied against the second portion of the part, and applying a thermochemical treatment to the third portion of the part.

A strip casting apparatus having a roll shell with a nitrided inner diameter surface mounted on a steel core and method of manufacturing the same. The inner diameter of a steel roll shell may be nitrided by ion or plasma nitriding. The nitriding process can form tight, crack free nitride layer that provides a corrosion resistant barrier and exhibits a surface hardness that is greater than the surface hardness of the steel core and that improves galling resistance while maintaining efficient heat transfer of the roll shell. After nitriding, the roll shell can be shrink fit over a steel core.

A strip casting apparatus having a roll shell with a nitrided inner diameter surface mounted on a steel core and method of manufacturing the same. The inner diameter of a steel roll shell may be nitrided by ion or plasma nitriding. The nitriding process can form tight, crack free nitride layer that provides a corrosion resistant barrier and exhibits a surface hardness that is greater than the surface hardness of the steel core and that improves galling resistance while maintaining efficient heat transfer of the roll shell. After nitriding, the roll shell can be shrink fit over a steel core.

A rotary compressor includes: a compressing unit that includes an annular cylinder, an end plate, an annular piston which is fit in an eccentric portion of a rotation shaft, and a vane which protrudes from the inside of a vane groove of the cylinder to the inside of an operation chamber, comes into contact with the annular piston, and partitions the operation chamber into an inlet chamber and a compression chamber. The vane is formed of steel and has a diamond-like carbon layer formed on a sliding surface with respect to the annular piston. The annular piston is formed of NiCrMo cast iron to which 0.15 wt % to 0.45 wt % of phosphorus is added, or is formed of cast iron or steel and has an iron nitride layer formed on an outer circumferential surface thereof.

A rotary compressor includes: a compressing unit that includes an annular cylinder, an end plate, an annular piston which is fit in an eccentric portion of a rotation shaft, and a vane which protrudes from the inside of a vane groove of the cylinder to the inside of an operation chamber, comes into contact with the annular piston, and partitions the operation chamber into an inlet chamber and a compression chamber. The vane is formed of steel and has a diamond-like carbon layer formed on a sliding surface with respect to the annular piston. The annular piston is formed of NiCrMo cast iron to which 0.15 wt % to 0.45 wt % of phosphorus is added, or is formed of cast iron or steel and has an iron nitride layer formed on an outer circumferential surface thereof.

A method for thermochemically treating a part while masking a portion and corresponding mask are provided. The method includes the steps of providing a mask comprising a body with a seat, at least a deformable sealing washer located in the seat, and a tightening bushing, the body having a cavity, placing a first portion of the part in the cavity, a second portion of the part being located in a passage in the sealing washer, and a third portion of the part being located outside the mask, moving the tightening bushing to its tightened position so that the sealing washer is deformed and applied against the second portion of the part, and applying a thermochemical treatment to the third portion of the part.

A method for thermochemically treating a part while masking a portion and corresponding mask are provided. The method includes the steps of providing a mask comprising a body with a seat, at least a deformable sealing washer located in the seat, and a tightening bushing, the body having a cavity, placing a first portion of the part in the cavity, a second portion of the part being located in a passage in the sealing washer, and a third portion of the part being located outside the mask, moving the tightening bushing to its tightened position so that the sealing washer is deformed and applied against the second portion of the part, and applying a thermochemical treatment to the third portion of the part.

Apparatus and methods associated with an enclosure or structure including two sections that are adapted with a snap-fit interlocking structure. Various embodiments of the enclosure or structures are formed with various case hardening or embrittlement processes to increase embrittlement or hardness of the enclosure or structure so as to create a structure or enclosure which has a desired fragmentation capacity while still maintaining sufficient material properties to permit snap-fit insertion of one section into another section and withstand substantial impacts. Embodiments also provide an interlocking structure that minimizes differences in fragmentation or fracturing capacity as contrasted with other portions of the structure or enclosure. An embodiment of the invention includes an enclosure where one section of the enclosure or structure has a first thickness and the second section has a second thickness, wherein the first and second thicknesses are different. In some embodiments, one section is thinner than another section.

Apparatus and methods associated with an enclosure or structure including two sections that are adapted with a snap-fit interlocking structure. Various embodiments of the enclosure or structures are formed with various case hardening or embrittlement processes to increase embrittlement or hardness of the enclosure or structure so as to create a structure or enclosure which has a desired fragmentation capacity while still maintaining sufficient material properties to permit snap-fit insertion of one section into another section and withstand substantial impacts. Embodiments also provide an interlocking structure that minimizes differences in fragmentation or fracturing capacity as contrasted with other portions of the structure or enclosure. An embodiment of the invention includes an enclosure where one section of the enclosure or structure has a first thickness and the second section has a second thickness, wherein the first and second thicknesses are different. In some embodiments, one section is thinner than another section.

Grain-oriented electrical steel sheets with good magnetic properties are industrially stably produced, by using as the material, a steel slab having a predetermined composition, wherein after cold rolling and before the start of secondary recrystallization annealing, the cold rolled sheet is subjected to nitriding treatment with nitrogen content of 50 mass ppm or more and 1000 mass ppm or less, and a total content of 0.2 mass % to 15 mass % of a sulfide and/or sulfate is contained in an annealing separator, and a staying time in the temperature range of 300 C. to 800 C. in the heating stage of secondary recrystallization annealing of 5 hours or more is secured to precipitate silicon nitride (Si.sub.3N.sub.4) and MnS, and using the silicon nitride in combination with MnS as inhibiting force for normal grain growth to significantly reduce variation of magnetic properties.