31results about How to "Prevents stress corrosion cracking" patented technology

A photocatalytic substance having the properties of an n-type semiconductor is deposited on a surface of a metal base made of a stainless steel or Inconel. When necessary, the hydrogen concentration of the reactor water is increased. A current produced by the photocatalytic substance when the same is irradiated with light or radioactive rays in a nuclear reactor flows through the metal base to reduce corrosion current. When necessary, the photocatalytic substance is provided on its surface with at least one of Pt, Rh, Ru and Pd.

A mechanical transducer induces liquid cavitation, causing pressure waves in a liquid which are applied against a metal surface to afford localized elastic and plastic tensile microstrain. The pressure waves alter the surface tensile stresses in the treated metal by reducing the tensile stresses or forming surface compressive stresses. A boot is provided about the operating face of the transducer for confining a liquid through which compression waves are generated and applied to the metal surface, the boot sealing about the transducer and the surface undergoing treatment.

According to the invention, an article that is exposed to high temperature e.g., over 1000.degree. C. during operation is disclosed. In one embodiment, a method for a gas turbine engine includes a directionally solidifed metallic substrate, e.g., a superalloy, which defines an airfoil, a root and a platform located between the blade and root. The platform has an underside adjacent the root, and a corrosion resistant overlay coating such as an MCrAlY or a noble metal containing aluminide or corrosion inhibiting ceramic is located on portions or the blade not previously covered with such coatings, e.g., the underside of the platform and the neck. The applied coating prevents corrosion and stress corrosion cracking of blade in these regions. Where the airfoil is also created, the airfoil coating may have a composition different from that of the coating on the underplatform surfaces.

The method of preventing cold-worked stress corrosion cracking in the iron steels and alloyed steels including stainless steels comprises removing a residual tensile stressed layer, optionally generating residual compression, through the impact of irradiation with the ultra-short femtosecond pulse and kW class high average-power laser, and removing a hardened surface layer extremely susceptible to stress corrosion cracking, whereby this susceptible hardened surface layer with many concentrated dislocation defects and the likes is removed without generating or introducing any of such hardened layer in the process of its removal. The method is free from the risk of damaging other equipment by peening with steel balls or other shaped shots, is almost unlimited in actual environment, effectiveness, work, place and other conditions for application, is inexpensive, and functions continuously for a much longer period than an ordinary nuclear reactor's service lifetimes.

The invention relates to a connecting method of a pressure vessel connecting pipe and a sealing head for reducing welding residual stress, which belongs to the technical field of sealing container processing and manufacturing. The connecting method is characterized by comprising the following steps of (a) opening the sealing head, and processing the connecting pipe (2); (b) extending one end of the connecting pipe (2) into a pressure vessel (1); (c) welding the sealing head and the connecting pipe (2); (d) preheating one side, which is positioned in the pressure vessel (1), of a welding seam (3), and then performing overlay welding on the root of the connecting pipe (2) in the pressure vessel (1); (e) preheating the inner wall of the connecting pipe (2), and then performing overlay welding on the inner wall of the connecting pipe (2); (f) cutting the connecting pipe (2) in the pressure vessel (1); (g) tempering the sealing head. According to the connecting method of the pressure vessel connecting pipe and the sealing head for reducing the welding residual stress, the welding residual stress is reduced in the manufacturing process of the pressure vessel, so that the structural integrity of the pressure vessel is increased, and the stress corrosion cracking resistant capability of a welding connector of the pressure vessel connecting pipe is enhanced.

A laser peening process for the densification of metal surfaces and sub-layers and for changing surface chemical activities provides retardation of the up-take and penetration of atoms and molecules, particularly Hydrogen, which improves the lifetime of such laser peened metals. Penetration of hydrogen into metals initiates an embrittlement that leaves the material susceptible to cracking.

In order to reduce a pressure loss in a check valve and simplify a manufacturing process, a check valve (10) configured to be disposed in piping of fluid is provided, which includes a valve housing (31) including a valve element (52) and a valve seat (54) therein, a casing (20) that is configured to place the valve housing therein, in which a casing flow path (60) is provided between the casing and the valve housing to make a flow of the fluid in an axial direction of the valve housing. In the valve housing, a communicating hole (38) and sealing portion (34) are formed. The communicating hole that is formed through the valve housing in a thickness direction thereof introduces the fluid, which flows through between the valve element and the valve seat at the open position of the check valve, into the casing flow path. The sealing portion that is provided on an outer surface of the valve housing upstream of the communicating hole in a flow direction of the fluid in the casing flow path, is configured to come into contact with an inner surface of the casing to seal the casing flow path and position the valve housing in a radial direction perpendicular to the axial direction relative to the casing.

A device for recovering residual heat from exhaust gas includes: a dry economizer which heats to-be-heated water by utilizing sensible heat of the exhaust gas, the dry economizer being provided in a duct extending to a funnel through which the exhaust gas is emitted to atmosphere; and a condensation economizer which heats to-be-heated water by utilizing latent heat of condensation of the exhaust gas, the condensation economizer being provided on a downstream side of the dry economizer. The duct includes an upstream duct in which the dry economizer is provided and a downstream duct connected to the upstream duct and directing the exhaust gas to flow upwardly. The condensation economizer is arranged in the downstream duct so that temperature of the exhaust gas amounts to condensation temperature at a vicinity of an upper part of the condensation economizer.

An austenitic stainless steel excellent in intergranular corrosion resistance and stress corrosion cracking resistance, comprising: C: 0.005 wt % or less; Si: 0.5 wt % or less; Mn: 0.5 wt % or less; P: 0.005 wt % or less; S: 0.005 wt % or less; Ni: 15.0 to 40.0 wt %, Cr: 20.0 to 30.0 wt %, N: 0.01 wt % or less; O: 0.01 wt % or less; and the balance of Fe and inevitable impurities, wherein the content of B included in the inevitable impurities is 3 wt ppm or less.

A high-strength aluminum alloy exhibiting excellent stress corrosion cracking resistance and excellent extrudability, and a method for producing an extruded shape using the same are disclosed. The aluminum alloy includes 1.6 to 2.6 mass % of Mg, 6.0 to 7.0 mass % of Zn, 0.5 mass % or less of Cu, and 0.01 to 0.05 mass % of Ti, with the balance being Al and unavoidable impurities.

The invention relates to a heat transfer tube (9) for falling film evaporation having a heating medium surface (21) to be heated by a heating medium, a falling film surface (20) to have spent liquor passing over it, and being made from an iron based high alloy stainless steel material with an alloy content above 16.00% for Chromium and above 1% for Nickel. The falling film surface of the heat transfer tube is equipped with at least one weld ridge (WR; WR₁, WR₂), said weld ridge having a height (h; h₂) in the range 0.3 to 5.0 mm, a width (w; w₂) in the range 0.5-15 mm, and an inclination angle (α; α₁, α₂) versus a plane orthogonal to a longitudinal axis (CC) of the heat transfer tube in a range of 0-70 degrees so that each weld ridge is inclined and extends helically along at least a portion of the heat transfer tube or extend within a plane orthogonal to the longitudinal axis of the heat transfer tube and forms well ridge portions on the falling film surface such that the distance along the longitudinal axis of the heat transfer tube between adjacent weld ridge portions is within the range of 0 to 250 mm. The invention also relates to a method for manufacturing said heat transfer tube.

Provided herein is a dual-phase stainless steel having excellent carbon dioxide corrosion resistance, excellent sulfide stress corrosion cracking resistance, and excellent sulfide stress cracking resistance. The dual-phase stainless steel contains, in mass %, C: 0.03% or less, Si: 1.0% or less, Mn: 0.10 to 1.5%, P: 0.030% or less, S: 0.005% or less, Cr: 20.0 to 30.0%, Ni: 5.0 to 10.0%, Mo: 2.0 to 5.0%, Cu: 2.0 to 6.0%, N: less than 0.07%, and the balance Fe and unavoidable impurities, and has a structure that is 20 to 70% austenite phase, and 30 to 80% ferrite phase in terms of a volume fraction.