Abstract: There is provided a seamless steel pipe for line pipe, wherein a chemical composition consists, by mass percent, of C: 0.03-0.10%, Si: ?0.50%, Mn: 1.0-2.0%, P: ?0.050%, S: ?0.005%, Cr: 0.05-1.0%, Mo: 0.01-0.30%, Al: 0.001-0.10%, N: ?0.01%, Ni: 0.04-2.0%, Ca: 0.0005-0.0050%, Cu: 0-2.0%, Ti: 0-0.05%, Nb: 0-0.05%, V: 0-0.10%, the balance: Fe and impurities, and satisfies the conditions of Cu+Ni: ?0.10%, and Mo+V: ?0.30%, wherein in a scale formed on the surface of the steel pipe, metal particles consisting mainly of Ni or Cu having an average circle-equivalent diameter of 0.1-5 ?m exist, and a distance from a boundary between the base metal of the steel pipe and the scale to a region in which the metal particles do not exist is 20 ?m or longer.

Abstract: There is provided a seamless steel pipe for line pipe, wherein a chemical composition consists, by mass percent, of C: 0.03-0.10%, Si: ?0.50%, Mn: 1.0-2.0%, P: ?0.050%, S: ?0.005%, Cr: 0.05-1.0%, Mo: 0.01-0.30%, Al: 0.001-0.10%, N: ?0.01%, Ni: 0.04-2.0%, Ca: 0.0005-0.0050%, Cu: 0-2.0%, Ti: 0-0.05%, Nb: 0-0.05%, V: 0-0.10%, the balance: Fe and impurities, and satisfies the conditions of Cu+Ni: ?0.10%, and Mo+V: ?0.30%, wherein in a scale formed on the surface of the steel pipe, metal particles consisting mainly of Ni or Cu having an average circle-equivalent diameter of 0.1-5 ?m exist, and a distance from a boundary between the base metal of the steel pipe and the scale to a region in which the metal particles do not exist is 20 ?m or longer.

Abstract: A stamper for use in producing high-density recording disks of the type in which an information signal pattern is formed as successive minute pits in a recording surface, is formed of glass and is manufactured by an image reversal photolithography process in which a film of a positive type of photoresist is scanned by a modulated light beam, baking is then executed to produce cross-linking of molecular chains within the portions of the photoresist which have been exposed to the scanning beam, and the photoresist is then subjected to overall flood exposure to light, whereby the photoresist portions which were not exposed to the scanning light beam can be removed by applying an alkaline solution. A photoresist pattern is thereby formed, to be used as an etching mask which can be patterned to a higher degree of resolution than has been possible hitherto, whereby a glass stamper for producing very high-capacity recording disks can be manufactured.

Abstract: In a method of fabricating a master recording disc, a photoresist layer is formed on a glass substrate to form a master blank, which is revolved and exposed to an intensity-modulated laser beam so that a series of optically excited regions is formed in track turns in the photoresist layer. The optically excited regions are removed, forming a series of pits in the photoresist layer. An etchant gas is sputtered onto the master blank until the pits in the photoresist layer extend through the boundary surface of the photoresist layer and the glass substrate to a desired depth and pits having side walls tapered in a direction away from the boundary surface are formed in the substrate. The photoresist layer which remains on the glass substrate is finally removed.