Hitachi, Ltd.

Tsutomu Onuma

Toshimi Matsumoto

Akira Onuma

Mitsuo Nakamura

Yasumasa Tamai

Keiichi Uraki

Kenichi Usami

Hiroshi Takayasu

Tsugio Yoshikawa

Masao Kawakami

Makoto Kanda

Toshitaka Satsuta

Tsugio Fushimi

Fumio Sakamoto

Hideo Suzuki

Hiroshi Sato

Takahiko Kato

Hisanori Okamura

Kunihiko Suzuki

Takao Funamoto

Ren Morinaka

Seishin Kirihara

Eisaku Hayashi

Fuminori Ishikawa

Hiroshi Yamauchi

Fumio Hataya

Masaki Murashita

Tatsuo Yonezawa

Shizuka Shimanuki

Koji Goto

Masami Yada

Osamu Matsushima

Choichi Asano

Masayuki Kurihara

Jun'ya Kaneda

Hiroo Koide

An underwater laser processing system has a laser torch; a laser torch driving mechanism for changing a laser emission position of the laser torch; and a chamber with one end opened to an external environment, which contains the laser torch; wherein a partitioning wall for preventing permeation of water is provided between a free end of the chamber and the laser torch. The system is used for detecting a sensitized portion and repairing it at one time using a sensitization detecting arrangement. Moreover, it is used for forming an alloying layer by melting a sprayed coating film, and for forming a new surface layer by emitting a laser beam through a solution containing a metal component.

Underwater laser processing device including chamber with partitioning

A submerged laser beam irradiation equipment provides a high quality submerged laser beam processing of a submerged workpiece using only a small amount of a gas. The submerged laser beam irradiation equipment has: a focus lens for focusing a laser beam; a mirror tube which houses the lens; a first nozzle operating to cover the front end of the mirror tube in an irradiating direction of the laser beam; a skirt portion provided at the front end of the first nozzle for preventing water intrusion thereinto; and a shutter mechanism operable to open and close and provided between said skirt portion and said mirror tube for preventing water intrusion into said mirror tube.

Submerged laser beam irradiation equipment

An ultra high head pumpturbine power generating plant with a turbine having a runner rotating with water flow supplied through a high head conducting tube. A rotary electric machine rotates with rotation of the runner. The head is in the range of 400-600 m, and the runner is at least 5 meters in diameter. The said runner has characteristics of toughness at room temperature: at least 500 N/mm.sup.2, or tensile strength at room temperature: at least 650 N/mm.sup.2, elongation at least 16%, reduction of area at least 45%, 2 mm U-notch impact value at 0.degree. C. at least 100 J, and fracture toughness at least 6000 N/mm.sup.3/2.

Stainless steel type 13Cr5Ni having high toughness, and usage of the same

A neutron-irradiated structural material having a defect in a nuclear reactor internals is repaired by covering the structural material to be repaired with a plate to cover over a portion thereof having the defect, and then welding the plate and the structural material by locally applying pressure on the surface of the plate and adding energy to the portion to which the pressure is applied thereby to generate thermal energy in the contact surfaces between the plate and the structural material.

Method of repairing structural materials of nuclear reactor internals

Method of welding a carbon steel and a austenitic stainless steel involves using high density energy beam like a laser beam or electron beam. Welding using high density energy beam is effective to obtain a high precision welding. For the purpose of obtaining both high precision and no cracks, and no deformation, the method of the invention controls the structure of a weld portion to be a mixed structure of an austenitic structure and not greater than 20 wt % of a ferritic structure.

Method of welding a carbon steel and an austenitic stainless steel

High toughness stainless steel type 13Cr5Ni containing C: 0.008-0.03% (by weight, all of the following elements), Si: max. 1%, Mn: max. 2%, Cr: 10.0-14.0%, Ni: 4.0-7.0%, and Mo: 0.2-2.0%, in which (Cr/Ni) ratio is in a range of 2.0-3.0 or (C/Mo) ratio is in a range of 0.015-0.1, as a structural material for fluid machinery, austenitic stainless steel containing C: 0.10-0.30% (by weight, all of the following elements), Si: max. 1%, Mn: max. 2%, Cr: 16.00-23.00%, Ni: 1.00-8.00%, and Co: 2.00-9.00%, and Ni+Co: 6.00-12.00% as a weld padding layer forming material, and fluid machinery using the same.

Stainless steel type 13Cr5Ni having high toughness, and usage the same

A welded structural member adapted to be subjected to a flowing fluid and comprising a base member consisting mainly of iron and a coating layer formed by a build-up welding on the surface of the base member, the coating layer having a higher erosion resistance than the base member. The coating layer contains 0.03 to 0.4 wt % of C, 0.1 to 1 wt % of Si, 0.5 to 20 wt % of Mn, 1 to 5.5 wt %, of Ni, 1 to 12 wt % of Co, 8 to 23 wt % of Cr and the balance Fe. The structure of the coating layer is mainly unstable austenite.

Welded structural member having high erosion resistance

A welded structure and a method for making same wherein a plurality of weld metals, such as martensitic steel and austenitic steel, differing in coefficient of thermal expansion from each other are deposited in a plurality of layers thicknesswise of the welded structure in a gap defined by structural members to be welded in such a manner that a layer of the weld metal of higher coefficient of thermal expansion is covered by a layer of the weld metal of lower coefficient of thermal expansion in a weld formed, to improve brittle fracture strength, fatigue strength and stress corrosion cracking resistance of the weld. By subjecting the welded structure to stress relief annealing treatment, it is possible to produce compressive stress on the surface of the layer of the weld metal of lower coefficient of thermal expansion.

Welded structure having improved mechanical strength and process for

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Hitachi, Japan

Tsutomu Onuma