Abstract: The present invention particularly has as its technical problem to provide austenitic stainless steel sheet used as the material for housings of turbochargers in which excellent heat resistance and workability are demanded. The austenitic stainless steel sheet according to the present invention comprises, by mass %, C: 0.005 to 0.2%, Si: 0.1 to 4%, Mn: 0.1 to 10%, Ni: 2 to 25%, Cr: 15 to 30%, N: 0.01 to less than 0.4%, Al: 0.001 to 1%, Cu: 0.05 to 4%, Mo: 0.02 to 3%, V: 0.02 to 1%, P: 0.05% or less, and S: 0.01% or less, comprises a balance of Fe and unavoidable impurities, and has an annealing twin frequency of 40% or more and is excellent in heat resistance.

Abstract: The present invention particularly has as its technical problem to provide austenitic stainless steel sheet used as the material for housings of turbochargers in which excellent heat resistance and workability are demanded. The austenitic stainless steel sheet according to the present invention comprises, by mass %, C: 0.005 to 0.2%, Si: 0.1 to 4%, Mn: 0.1 to 10%, Ni: 2 to 25%, Cr: 15 to 30%, N: 0.01 to less than 0.4%, Al: 0.001 to 1%, Cu: 0.05 to 4%, Mo: 0.02 to 3%, V: 0.02 to 1%, P: 0.05% or less, and S: 0.01% or less, comprises a balance of Fe and unavoidable impurities, and has an annealing twin frequency of 40% or more and is excellent in heat resistance.

Abstract: A method of increasing the thickness of a tube which increases a thickness of an end part of a tube without a burr being formed, comprising placing a tube 21 between a die 25 and mandrel 22 in the state with a space for increasing the thickness between a small diameter part 22a of the mandrel 22 and a first end part 21a of a tube 21 and between a large diameter hole part 25C of the die 25 and a second end part 21b of the tube 21, using a first upsetting punch 23 and a second upsetting punch 24 to respectively process the first end part 21a and the second end part 21b of the tube 21, pulling out the mandrel 22 from the tube 31 in the state with the second upsetting punch 24 constraining the second end part 31b of the tube 31, and using the first upsetting punch 23 to push up the first end part 31a of the tube 31 to take out the tube 31 from the die 25.

Abstract: This heat-resistant austenitic stainless steel sheet contains, in mass %, C: 0.05 to 0.15%, Si: 1.0 to 3.5%, Mn: 0.5 to 2.0%, P: not more than 0.04%, S: not more than 0.01%, Cr: 23.0 to 26.0%, Ni: 10.0 to 15.0%, Mo: 0.50 to 1.20%, Ti: not more than 0.1%, Al: 0.01 to 0.10% and N: 0.10 to 0.30%, wherein the total amount of C and N (C+N) is from 0.25 to 0.35%, and the balance is composed of Fe and unavoidable impurities. The heat-resistant austenitic stainless steel can be used in a high-temperature environment that reaches a maximum temperature of 1,100° C.

Abstract: A stainless steel sheet free of surface flaws, having an enhanced high temperature strength and corrosion resistance, not becoming brittle at a high temperature, and further exhibiting a high oxidation resistance enabling it to be suitably used as an inside pipe of a double pipe of an exhaust manifold, a turbocharger part, and other automobile exhaust system parts, which stainless steel sheet has a predetermined composition of chemical components and satisfies Cr+20Mo?24.0%, and Si+20C+15N?5.8%. Further, an automobile exhaust system part, excellent in both the oxidation resistances of the base material and weld zone using the above stainless steel sheet, having a gradient of change of sheet thickness between the weld metal and the base material of the above stainless steel sheet of 15 degrees or less.

Abstract: A method of increasing the thickness of a tube which increases a thickness of an end part of a tube without a burr being formed, comprising placing a tube 21 between a die 25 and mandrel 22 in the state with a space for increasing the thickness between a small diameter part 22a of the mandrel 22 and a first end part 21a of a tube 21 and between a large diameter hole part 25C of the die 25 and a second end part 21b of the tube 21, using a first upsetting punch 23 and a second upsetting punch 24 to respectively process the first end part 21a and the second end part 21b of the tube 21, pulling out the mandrel 22 from the tube 31 in the state with the second upsetting punch 24 constraining the second end part 31b of the tube 31, and using the first upsetting punch 23 to push up the first end part 31a of the tube 31 to take out the tube 31 from the die 25.

Abstract: This heat-resistant austenitic stainless steel sheet contains, in mass %, C: 0.05 to 0.15%, Si: 1.0 to 3.5%, Mn: 0.5 to 2.0%, P: not more than 0.04%, S: not more than 0.01%, Cr: 23.0 to 26.0%, Ni: 10.0 to 15.0%, Mo: 0.50 to 1.20%, Ti: not more than 0.1%, Al: 0.01 to 0.10% and N: 0.10 to 0.30%, wherein the total amount of C and N (C+N) is from 0.25 to 0.35%, and the balance is composed of Fe and unavoidable impurities. The heat-resistant austenitic stainless steel can be used in a high-temperature environment that reaches a maximum temperature of 1,100° C.

Abstract: In a roller support device, an inner peripheral surface of a bearing box is covered with a material having a poor wettability with respect to a molten metal, such as tantalum, graphite, C/C composite, silicon carbide or the like. The molten metal does not adhere to the covered portion, or even if the molten metal adheres to and is solidified on the covered portion, the molten metal can be peeled off with a light force. Therefore, after a support roller is pulled up from the molten metal, the molten metal does not prevent a rolling bearing from shifting in the axial direction thereof so that the roller support device can prevent an excessive force from being applied to the rolling bearing when the support roller, after it is thermally expanded once, is contracted as the temperature falls.

Abstract: A surface-coated steel sheet having improved corrosion resistance and suitable for use as automobile inner and outer panels comprises a steel sheet having on at least one surface thereof a composite coating which comprises the following layers (a) to (d) from the bottom to the top of the coating:(a) a first zinc alloy plating layer with a coating weight of 10-100 g/m.sup.2 which contains at least one of Ni and Co in an amount satisfying the following inequality:0.05.ltoreq.(5.times.Co)+Ni.ltoreq.10 (in weight percent),(b) a second zinc alloy plating layer with a coating weight of 0.05-10 g/m.sup.2 which contains at least one of Ni and Co in an amount satisfying the following inequality:10<(5.times.Co)+Ni.ltoreq.40 (in weight percent),(c) a chromate film layer with a coating weight of 20-300 mg/m.sup.2 as Cr, and(d) an organic coating layer with a thickness of 0.2-5 .mu.m.

Abstract: A continuous multi-layer plating line for steel sheet which includes a hot-galvanizing apparatus to form a galvanized coating and optionally to alloy the coating and an electroplating apparatus to form an electroplated coating on the galvanized coating. Between the hot-galvanizing apparatus and the electroplating apparatus, a post-galvanizing surface treatment apparatus effective for removing surface oxide contaminants and activating the surface of the galvanized coating is disposed and the galvanized steel sheet is treated thereby prior to electroplating. The post-galvanizing surface treatment may be carried out by applying an alkali solution or an acid which can dissolve aluminum oxide to the galvanized coating, by alkali electrolysis, by cathodic electrolysis, by cooling the galvanized steel sheet with an alkali solution, or by skin-pass rolling using an alkali solution or an acid which can dissolve aluminum oxide as a skin-pass roling liquid.