Abstract: A laser welded steel pipe having a weld zone containing a steel pipe containing 0.01 to 0.2 weight % C, 1 weight % or less S, 0.05 to 2 weight % Mn and 6 weight % or less Mn. The weld zone has a melted and solidified metal structure containing carbon and oxygen which satisfy the following equations:(carbon weight %)(oxygen weight %).ltoreq.0.006for a steel pipe containing carbon in an amount of less than 0.2 weight %, and(oxygen weight %).gtoreq.0.02.A method for manufacturing a laser-welded steel pipe including producing an open pipe made from a hot-rolled steel strip with opposing edge portions facing each other by employing a formal roll, preheating the two edge portions, pressing the two edge portions to butt against each other by using squeeze rolls and welding the butted edge portions by irradiation with a laser beam to heat and melt the two edge portions.

Abstract: A laser-welded steel pipe includes: a steel pipe consisting essentially of C in an amount of 0.01 to 0.5 wt. %, Si in an amount of 1 wt. % or less, Mn in an amount of 0.05 to 2 wt. % and Cr in an amount of 6 wt. % or less; and a weld zone having a melted and solidified metal structure containing carbon and oxygen. The carbon content, ?C wt. %!, and the oxygen content, ?O wt. %!, in the melted and solidified metal structure satisfies the following equations:?C wt. %!.times.?O wt. %!.ltoreq.0.006, for the steel pipe containing C in an amount of less than 0.2 wt. %,?O wt. %!.ltoreq.0.03, for the steel pipe containing C in an amount of 0.2 wt. % or more.

Abstract: The object of the present invention is to provide titanium discs to be used as high-density read-while-write magnetic discs. Further object of the present invention is to provide said titanium discs coated with a non-magnetic plated layer.Titanium discs to be used as magnetic discs which satisfy the above object have the following structures: A titanium disc to be used as magnetic disc having the mean height of the peaks from the center line, R.sub.a, of 0.0002 .mu.m to 0.0060 .mu.m and pits on its surface of 25 .mu.m or less in diameter or 5 .mu.m or less in depth. Further, said titanium disc to be used as a magnetic disc is coated with a non-magnetic plated layer with a thickness of 0.09 .mu.m to 5 .mu.m. Moreover, a titanium disc that is most suitable to be used as a magnetic disc is the titanium disc provided with a plated layer of 30/100 or less in a knife-cut peeling test.

Abstract: A silicon single crystal manufacturing apparatus according to the CZ method which includes a partition member for dividing a quartz crucible into a single crystal growing section and a material melting section and having at least one small hole for permitting the passage of molten silicon, and a heat keeping cover for covering the partition member and the material melting section. The heat keeping cover is made of a sheet of metal selected from the group consisting of Ta, Mo and W and containing Fe 50 ppm or less and Cu 10 ppm or less. The metal sheet includes a surface layer composed of a silicon-enriched layer, and the depth of an area of the silicon-enriched layer in which the content of Si is greater than the contents of Fe and Cu at the same position therein is not less than 10 .mu.m from the surface. The content of Fe in the silicon-enriched layer is not greater than 5 ppm.

Abstract: A method of manufacturing a magnetic disk substrate made of titanium, in which chemical etching is performed on a titanium disk for magnetic disk substrate, thereby removing a surface portion thereof having a thickness of at least 2 nm, and the new surface of the titanium disk, formed by the chemical etching, is anodized, thereby forming anodized film on the titanium disk.

Abstract: An apparatus for manufacturing a single silicon crystal comprises a quartz crucible accomodated into a graphite crucible, a partition member partitioning molten silicon material in the quartz crucible into a single silicon growing portion on the inner side and a material melting portion on the outer side, a heater for maintaining the molten silicon material in the single silicon growing portion at a temperature appropriate for growing the single silicon crystal and for supplying heat for melting the raw materials fed into the material melting portion, and small holes made in the partition member. The partition member is made of an opaque quartz glass. The material melting portion is replenished with the raw materials and single silicon crystal is pulled from the single silicon growing portion. Molton silicon material moves from the material melting portion into the single silicon growing portion through small holes made in the partition member.

Abstract: A film forming apparatus comprises a reaction furnace having a reaction chamber therein, injection nozzles for introducing a reactive fluid, provided on the reaction furnace, a discharge nozzle for discharging a reactive fluid, provided on the reaction furnace, and a pair of susceptors located in almost vertical position in the reaction chamber and having facing sides separated by a specified distance. The susceptors include a plurality of depressions formed in the respective facing sides thereof for holding a plurality of silicon wafers. The paired susceptors are rotated in mutually opposite directions.

Abstract: An apparatus for forming epitaxial layers, comprises a first susceptor disposed in a reaction furnace and having an outer periphery constituted by a heat reflection material and capable of supporting a plurality of semiconductor wafers, a second susceptor disposed coaxially with the first susceptor such as to surround the first susceptor at a predetermined space therefrom and having an inner periphery constituted by a heat reflection material and capable of supporting a plurality of semiconductor wafers such that these semiconductor wafers face the semiconductor wafers supported by the first susceptor, and a pair of heat reflection members disposed in the reaction furnace between the outer periphery of the first susceptor and the inner periphery of the second susceptor. The first and second susceptors are rotated in mutually opposite directions about a common vertical axis during an epitaxial growing process.