[Problem] There is provided a colored stainless-steel product having excellent viewing-angle color tone discrimination and excellent corrosion resistance, in which a chemical coloration technique having sophisticated industrial color tone is used. [Solution] The product is a chemically-colored stainless-steel product having an uneven surface formed by a grinding treatment, wherein the 60-degree specular gloss [Gs (60 degrees)] of the uneven surface is 5 to 50. The grinding treatment is performed by a single sandblasting treatment or a combination of the sandblasting treatment and an electrolytic polishing treatment. The sandblasting treatment is performed with a projection material configured from inorganic particles having a Mohs' hardness of at least six. A manufacturing method includes a sandblasting treatment step, an electrolytic polishing treatment step, a coloration treatment step for dipping stainless steel in a coloration treatment solution including a mixed solution of a chromic acid and a sulfuric acid to generate a colored film thereon, and a curing treatment step for dipping the coloration-treated stainless steel in a curing treatment solution including a mixed solution of a chromic acid and a phosphoric acid to cure the colored film.

[Problem] There is provided a colored stainless-steel product having excellent viewing-angle color tone discrimination and excellent corrosion resistance, in which a chemical coloration technique having sophisticated industrial color tone is used. [Solution] The product is a chemically-colored stainless-steel product having an uneven surface formed by a grinding treatment, wherein the 60-degree specular gloss [Gs (60 degrees)] of the uneven surface is 5 to 50. The grinding treatment is performed by a single sandblasting treatment or a combination of the sandblasting treatment and an electrolytic polishing treatment. The sandblasting treatment is performed with a projection material configured from inorganic particles having a Mohs' hardness of at least six. A manufacturing method includes a sandblasting treatment step, an electrolytic polishing treatment step, a coloration treatment step for dipping stainless steel in a coloration treatment solution including a mixed solution of a chromic acid and a sulfuric acid to generate a colored film thereon, and a curing treatment step for dipping the coloration-treated stainless steel in a curing treatment solution including a mixed solution of a chromic acid and a phosphoric acid to cure the colored film.

An erosive jet can propel degradable, abrasive grit conveyed in a carrier fluid to erode a downhole structure, such as a tubular (e.g., cutting through a tubular) or formation (e.g., perforation actions). The abrasive grit can be selected to degrade or dissolve in the wellbore fluid (e.g., in carrier fluid pumped into the wellbore or in fluid originating from the wellbore). The abrasive grit can provide increased cutting or erosion efficiency in the erosive jet during the cutting operation, then may degrade (e.g., dissolve) in the wellbore fluid to avoid certain complications, such as clogging or residue build-up in the wellbore formation or on downhole equipment. A degradation accelerator can be introduced (e.g., in carrier fluid) to accelerate degradation of the abrasive grit in the wellbore fluid. Degradation accelerators can be temperature-activated, pH-activated, or otherwise time-delayed so the abrasive grit remains sufficiently intact to perform the desired erosion operation.

An erosive jet can propel degradable, abrasive grit conveyed in a carrier fluid to erode a downhole structure, such as a tubular (e.g., cutting through a tubular) or formation (e.g., perforation actions). The abrasive grit can be selected to degrade or dissolve in the wellbore fluid (e.g., in carrier fluid pumped into the wellbore or in fluid originating from the wellbore). The abrasive grit can provide increased cutting or erosion efficiency in the erosive jet during the cutting operation, then may degrade (e.g., dissolve) in the wellbore fluid to avoid certain complications, such as clogging or residue build-up in the wellbore formation or on downhole equipment. A degradation accelerator can be introduced (e.g., in carrier fluid) to accelerate degradation of the abrasive grit in the wellbore fluid. Degradation accelerators can be temperature-activated, pH-activated, or otherwise time-delayed so the abrasive grit remains sufficiently intact to perform the desired erosion operation.

A hollow spring includes a steel tube in which the average of surface roughness is smaller than 10 μm across the entire inner surface of the steel tube and/or compressive residual stress is given to the entire inner surface of the steel tube. The hollow spring may be manufactured by a step of polishing the inner surface of the steel tube by flowing a viscoelastic abrasive medium (200) within the tubular member (10), between a first opening (11) and a second opening (12) of the tubular member (10). The abrasive medium (200) may include a viscoelastic base material and a granular abrasive. The inner surface of the steel tube is polished evenly to reduce the surface roughness and/or is given compressive residual stress to increase the fatigue life of the hollow spring.

The present invention relates to a glass sheet including a first main surface and a second main surface opposing the first main surface, in which the glass sheet has an affected layer directly below the first main surface, in at least a part of the first main surface, an average element length RSm is from 2500 nm to 6000 nm, a root-mean-square height Sq is from 3 nm to 45 nm, and a skewness Ssk is a negative value.

A method for treating and phosphatizing a metal board without using acid includes the following steps: performing a degreasing step to remove grease and dirt from a surface of the metal board with a degreasing agent; performing a blast-peening step by blasting and peening polygon blast-peening granules on the metal board through a centrifugal impeller to remove an oxidized layer; performing a washing step to clean remaining powders from the metal board after the blast-peening step; performing a phosphatizing step to form a protective phosphate coating on the metal board; performing another washing step to wash off remaining phosphatizing agents from the metal board; performing a rustproofing step to apply a rustproofing agent on the metal board; and performing a drying step to dry the metal board.

A method for treating and phosphatizing a metal board without using acid includes the following steps: performing a degreasing step to remove grease and dirt from a surface of the metal board with a degreasing agent; performing a blast-peening step by blasting and peening polygon blast-peening granules on the metal board through a centrifugal impeller to remove an oxidized layer; performing a washing step to clean remaining powders from the metal board after the blast-peening step; performing a phosphatizing step to form a protective phosphate coating on the metal board; performing another washing step to wash off remaining phosphatizing agents from the metal board; performing a rustproofing step to apply a rustproofing agent on the metal board; and performing a drying step to dry the metal board.

A cutting tool including a rake face, a flank face, and a cutting edge portion, comprising a substrate and an AlTiN layer, the AlTiN layer including cubic Al.sub.xTi.sub.1-xN crystal grains, Al having an atomic ratio x of 0.7 or more and less than 0.95, the AlTiN layer including a central portion, the central portion at the rake face being occupied in area by (111) oriented Al.sub.xTi.sub.1-xN crystal grains at a ratio of 50% or more and less than 80%, the central portion at the cutting edge portion being occupied in area by (111) oriented Al.sub.xTi.sub.1-xN crystal grains at a ratio of 80% or more.

A sand source selecting structure for a sandblasting gun has a main body; a channel provided in the main body, for passing a high pressure gas; at least two sub-channels provided in the main body respectively connected to the channel; a sandbox mounted on the main body connected to the channel through each of the sub-channels; at least one supply tube; a first control valve installed in the main body, for connecting the sandbox and at least one of the sub-channels of the channel; and a second control valve installed in the main body, for connecting the channel and another sub-channel of the supply tube. Therefore, the combination of the first control valve and the second valve provides a selecting structure, which can offer different sand supply sources.