Abstract: A hot-press molding method of the present disclosure includes a first heating process in which a steel plate is heated and the entire steel plate becomes austenite, a first cooling process in which a cooling rate of the steel plate after the first heating process is partially changed, a first region which is a part of the steel plate is transformed into martensite, and a second region other than the first region remains as austenite, a second heating process in which the entire steel plate is reheated and the first region becomes tempered martensite, and a second cooling process in which the entire steel plate after the second heating process is cooled. At least one of the first cooling process and the second cooling process is performed during a molding process in which the steel plate is press-molded on a molding die.

Abstract: A method for quenching a steel pipe by water cooling from an outer surface thereof, where pipe end portions are not subjected to water cooling, and at least part of a main body other than the pipe end portions is subjected to water cooling. A region(s) that is not subjected to direct water cooling over an entire circumference thereof can be along an axial direction at least in part of the main body other than the pipe end portions. The start and stop of water cooling can be intermittent at least in part of the quenching. During the water cooling of the pipe outer surface, an intensified water cooling can be performed in a temperature range in which the pipe outer surface temperature is higher than Ms point. Thereafter, the cooling can be switched to moderate cooling so that the outer surface is cooled down to Ms point or lower.

Abstract: According to the method of production of a steel sheet pressed part with locally modified properties, the steel sheet blank is first heated in a device for heating to the austenitic temperature of the material. Next, the steel sheet blank is converted in a tool for deep drawing by deformation into a final drawn part. Subsequently, the final drawn part is cooled inside the tool for deep drawing. Various locations of the final drawn part are cooled to various temperatures and/or at various rates during the cooling process. Thereafter, the drawn part is placed in an annealing device, where retained austenite stabilization occurs by diffusion-based carbon partitioning within the material from which the drawn part is made. After stabilization, the final drawn part is removed from the annealing device and air cooled to ambient temperature.

Abstract: The invention relates to a furnace system and a method for the controlled heat treatment of sheet metal components in individual component zones. The invention proposes a furnace system that is suitable for partly heating components made of steel sheet to a temperature above the AC3 temperature. The furnace system has a production furnace for heating the steel sheet parts to a temperature that is close to but below the AC3 temperature, said furnace system further having a profiling furnace with at least one level. The at least one level has an upper and a lower part and a product-specific intermediate flange that is introduced into a corresponding receiving area. The product-specific intermediate flange is designed to impose a specified temperature profile on the component with temperatures over AC3 for regions to be hardened and below AC3 for softer regions. Furthermore, the invention relates to a corresponding method for partly heating steel sheet parts to a temperature above the AC3 temperature.

Abstract: The invention relates to a method for producing partially hardened steel components in which a blank is subjected to a temperature increase that is sufficient for a quench-hardening and after reaching a desired temperature, the blank is transferred to a forming tool in which the blank is quench-hardened or the blank is cold-formed and the component obtained by the cold-forming is then subjected to a temperature increase. During the heating of the blank or component, absorption masses rest against and/or are spaced with a small gap apart from regions that are intended to have a lower hardness and/or higher ductility; with regard to its expansion and thickness, its thermal conductivity, and its thermal capacity and/or with regard to its emissivity, the absorption mass is dimensioned so that the thermal energy acting on the component in the region to remain ductile flows through the component into the absorption mass.

Abstract: A bearing component formed from a bearing steel, wherein the component has an outer surface and comprises through-hardened bainite and/or martensite and has a substantially homogeneous chemical composition, at least a part of the bearing component having a compressive residual stress profile comprising ?25 to ?1000 MPa at the near surface, wherein the near surface is defined as a region 500 microns or less below the outer surface.

Abstract: The invention provides a method of cooling a rail weld zone. The method includes a first rail web portion cooling process of cooling a rail web portion cooling region of the rail weld zone in a part of a temperature range until the completion of transformation from austenite to pearlite, a second rail web portion cooling process of cooling the rail web portion cooling region after the entire rail web portion of the rail weld zone is transformed to pearlite, a foot portion cooling process of cooling a foot portion of the rail weld zone, and a head portion cooling process of cooling a head portion of the rail weld zone. When cooling time of the first and second rail web portion cooling processes is t minute, a k value satisfies an expression represented as ?0.1t+0.63?k??0.1t+2.33.

Abstract: As to the method for fabricating a member of a vehicle, after a member for the vehicle having high-rigidity of martensite organization is fabricated by a hot stamping forming, the martensite organization is transformed to a ferrite having a low-rigidity partially and improved toughness or to a metal organization heat treated by tempering process through induction heating or secondary heat treatment using laser beam of conduction area, and thereby collision absorption performance is improved by stabilizing the absorption directivity of the collision energy without additional reinforcement.

Abstract: A hemispherical shoe (sliding member) 1 has a flat sliding surface 3, which is quenched to form a quenched portion 7. A part of the quenched sliding surface is partially annealed to form an annealed portion 6. When an oil film pressure acts on the sliding surface 1, the annealed portion 6 is deformed by pressure so that the surface thereof has a concave portion 6A. In the annealed portion 6, a remaining quenched portion 8 may remain at the center part thereof. The concave portion 6A can be used as an oil reservoir or an oil flow path, so that an excellent seizure resistance can be ensured.

Abstract: A cooling device and a cooling method for a hot strip allow uniform and stable cooling of the strip at a high cooling rate when supplying the coolant to the upper surface of the hot strip. The cooling device includes an upper header unit 21 for supplying a rod-like flow to the upper surface of the strip 10. The upper header unit 21 is formed of the first upper header group including plural first upper headers 21a arranged in a conveying direction and a second upper header group including plural second upper headers 21b arranged in the conveying direction. The cooling device is provided with an ON-OFF mechanism 30 to allow each of the upper headers 21a and 21b of the first and the second upper header groups to independently execute the ON-OFF control (start/end injection control) of an injection (feeding) of the rod-like flow.

Abstract: A system and method for producing locally austempered ductile iron includes a computer program for closely controlling the heating and cooling of an iron part or workpiece. The process allows for the austempering of a relatively low cost iron workpiece to produce significantly higher quality end products. The locally austempered regions may be formed to a substantial controlled depth.

Abstract: A cooling method of steel plate able to raise a cooling uniformity in a steel plate conveyance direction comprising, at a front stage part of a cooling apparatus, not spraying while a front end region of steel plate is passing, spraying by successively increasing the cooling water rate from 80 to 95 vol % (Qfront) of a standard water density when the front part region passes so that the amount of cooling water becomes the standard water density when a boundary part of the front part region and a center part region arrives, and continuing spraying by the standard water density while the center part region is passing, then, at a rear stage part of the cooling apparatus, spraying by making the amount of cooling water 80 to 95 vol % of the standard water density while the front end region of the steel plate is passing, successively increasing the amount of cooling water rate from 80 to 95 vol % of the standard water density when the front part region passes so that the amount of cooling water becomes the standard

Abstract: A method of manufacturing a blade including heating and quenching a coil of strip steel material to harden the material, heating the strip steel material to temper the material, grinding a first angle along an edge of the material, and subsequent to the grinding, re-hardening, for example by induction heating, the edge of the material.

Abstract: The method for manufacturing a martensitic stainless pipe includes heating the steel pipe until the external surface temperature thereof reaches a predetermined temperature not lower than A3 transformation point+20° C. and not higher than 980° C. The heated steel pipe is first water cooled until the external surface temperature thereof reaches a predetermined temperature not lower than 350° C. The water cooled steel pipe is air cooled until the external surface temperature thereof reaches a predetermined temperature not higher than 250° C. The air cooled steel pipe is either water or air cooled until the external surface temperature thereof reaches normal temperature. The cooling rate of the steel pipe in the first cooling step is determined according to the wall thickness of the steel pipe so that the amount of heat recuperation for the external surface temperature of the steel pipe in the second cooling step is not higher than 50° C.

Abstract: The present invention provides a fire resistant steel material excellent in high temperature strength, toughness, and reheating embrittlement resistance containing, by mass %, C: 0.001% to 0.030%, Si: 0.05% to 0.50%, Mn: 0.4% to 2.0%, Nb: 0.03% to 0.50%, Ti: 0.005% to less than 0.040%, N: 0.0001% to less than 0.0050%, and Al: 0.005% to 0.030%, limiting P: 0.03% or, less and S: 0.02% or less, satisfying C—Nb/7.74?0.005 and 2?Ti/N?12, and having a balance of Fe and unavoidable impurities and, further, a process for production of a fire resistant material comprising heating a steel slab comprised of this chemical composition to 1100 to 1350° C. and hot rolling it by a cumulative reduction rate at 1000° C. or less of 30% or more.

Abstract: To provide a vehicle which can move independently as an own independent vehicle and can run integrally in linkage with another vehicle. A plurality of single-seat vehicles which can move independently are combined and they move integrally while a predetermined formation is maintained through linkage among respective vehicles. One of all the vehicles moving in linkage serves as a host vehicle and an occupant in the host vehicle becomes a driver in the linkage moving. A host vehicle 1 runs with speed/direction according to running operation conducted by an occupant. Simultaneously therewith, the host vehicle 1 instructs following vehicles 2 to 4 to synchronize (follow) the host vehicle. The host vehicle 1 transmits a speed, a direction, and a relative position to the host vehicle to the following vehicles 2 to 4 as moving information in order to synchronize the following vehicles with the host vehicle (maintain linkage relationship).

Abstract: The present invention provides a fine grain surface layer steel part having a high proof strength ratio equal to or higher than that of conventional quenched and tempered materials, that is, a fine grain surface layer steel part containing, by mass %, C: 0.45% to 0.70%, Nb: 0.01% to 0.60%, Si: 0.10% to 1.50%, Mn: 0.40% to 2.0%, P: 0.10% or less, S: 0.001% to 0.15%, and N: 0.003% to 0.025% and having a balance of Fe and unavoidable impurities, where the surface layer and inside at all or part of the part have structures of different average particle sizes of ferrite crystal grains surrounded by high angle grain boundaries of a misorientation angle of 15 degrees or more and a method of production of that part comprising warm forging locations where strength is required to a predetermined shape at 1000° C. to 800° C. during which working so as to give an equivalent strain of 1.5 or more.

Abstract: A method for tempering a workpiece is provided. The method includes providing a ferrous alloy workpiece having a martensite and/or bainite phase therein, heating at least a portion of the workpiece to a preselected temperature and then cooling the workpiece to a lower temperature. The preselected temperature is below the austensizing temperature of the alloy and the heating is accomplished in no more than 60 seconds. One embodiment of the present invention heats the workpiece using resistance heating.

Abstract: A hot forged product including hardened areas introduced by partial cooling after hot forging, and unhardened areas, wherein Vickers hardness V1 of the hardened areas on the surface and Vickers hardness V2 of the unhardened areas satisfy the following formula (1): (V1?V2)/V2: 0.1 to 0.8.

Abstract: A method of cooling both surfaces of steel plate, which stably secures precision of cooling control from a start of cooling to an end so as to uniformly cool the top and bottom surfaces of the steel plate and thereby stably secures the steel plate quality and cools the steel plate down to a target temperature with a good precision. The method comprises dividing a steel plate cooling region into at least a spray impact part region and a spray non-impact part region, predicting a heat transfer coefficient for each divided region in advance, computing a predicted temperature history of the steel plate based on this predicted value, and setting and controlling amounts of sprayed coolant on the spray impact part regions by top and bottom surface nozzles.

Abstract: Various inexpensive rolling elements for use under high interface pressure such as induction hardened gears are provided, which have improved seizure resistance at tooth flanks and a temper hardness of HRC 50 or more at 300 ° C. To this end, a rolling element is made from a steel material which contains at least 0.5 to 1.5 wt % carbon and 0.2 to 2.0 wt % one or more alloy elements selected from V, Ti, Zr, Nb, Ta and Hf; and in which 0.4 to 4.0% by volume one or more compounds selected from the carbides, nitrides and carbonitrides of the above alloy elements and having an average particle diameter of 0.2 to 5 ?m are dispersed. In such a rolling element, the soluble carbon concentration of a martensite parent phase of a rolling contact surface layer is adjusted to 0.3 to 0.8 wt %, the martensite parent phase having been subjected to induction hardening and low temperature tempering, and one or more of the above carbides, nitrides and carbonitrides are dispersed in an amount of 0.4 to 4.

Abstract: There is provided an inexpensive rolling element used under high interface pressure such as induction hardened gears, the rolling element being improved in the seizure resistance of its tooth flanks and having a temper hardness of HRC 50 or more at 300° C. To this end, the rolling element is made from a steel material containing at least 0.45 to 1.5 wt % C and one or more alloy elements selected from 0.1 to 0.5 wt % V and 0.3 to 1.5 wt % Cr, and has a rolling contact surface layer having a structure tempered at low temperature in which 2 to 18% by volume cementite disperses in a martensite parent phase formed by induction heating and cooling and containing 0.25 to 0.8 wt % carbon solid-dissolving therein.

Abstract: A method of manufacturing a clutch housing having a boss portion and a drum portion integrally provided with the boss portion, is characterized by steps of integrally forming the boss portion and the drum portion by hot forging, and forced-cooling at least a portion of the boss portion, continuous to the integrally forming step.

Abstract: A road wheel composition having high surface hardness and high strength, which is manufactured by a heat treatment of a metal powder containing Fe as a main component, C, Si, Mn, P, S, Al, Ti, N, Cr, and B, and a method for manufacturing a road wheel for an automobile having high surface hardness and high strength by quenching an end of a formed road wheel rim by means of high-frequency heater and cooler using the road wheel composition. Road wheel composition includes Fe as a main component, C of 0.10 to 0.40 wt %, Si of 0.15 to 0.35 wt %, Mn of 0.35 to 2.0 wt %, P of not exceeding 0.03 wt %, S of not exceeding 0.3 wt %, Al of 0.05 to 0.15 wt %, Ti of 0.005 to 0.03 wt %, Nb of 0.025 to 0.045 wt %, Cr of not exceeding 0.35 wt %, and B of not exceeding 0.005 wt %. Road wheel having excellent surface hardness and high strength is manufactured.

Abstract: A method, which is used to make controlled defects corresponding to natural flaws and residual stresses in various kinds of test pieces. Defects identical to natural flaws are required to qualify non-destructive testing (NDT) procedures. In the method, sequential, repeated, heating-cooling cycles are used to create defects and residual stresses. The shape of the heating and cooling pattern, the duration of the heating and cooling, and the number of thermal cycles are used to control the size of the defects and residual stresses obtained. The defect is grown without initial flaw or other nucleator. The defects correspond to natural flaws in terms of morphology and also of the signals obtained with NDT methods, and are suitable for use in, for example, NDT-qualification blocks.

Abstract: The creep strength of a welded joint portion is improved, and damage of the welded joint portion based on the generation or development of cracks is suppressed. A postweld heat treatment process, wherein a welded joint made of carbon steel and low alloy steel is held within austenite single-phase temperature range for a given time and subsequently the joint is cooled by air-cooling or by slow cooling at a cooling rate lower than that of the air-cooling.

Abstract: A method of performing a heat treatment on steel rings, in particular for bearings, whereby the outer surface and inner surface of a preheated ring are exposed to different flows of a cooling medium such that the regions of the ring adjacent those surfaces are subjected to different cooling processes. The flow supply of the cooling medium is controlled in such a way that a desired internal stress pattern is obtained in the ring. The cooling medium includes of a combination of liquid and gas. An apparatus for performing a heat treatment on steel rings includes a support means for a ring to be treated; first and second supply means for supplying a spray or mist of a liquid, gas or combination thereof to the outer surface or inner surface of the ring, control means for controlling the supply of the spray or mist is also disclosed.

Abstract: In CrMoV based heat resistant steels and tungsten-containing CrMoV based heat resistant steels, trace impurities, such as phosphorus, sulfur, copper, aluminum, arsenic, tin, and antimony are reduced lower than a specific level. Furthermore, alloy steels having increased creep strengths in a creep test on an unnotched test piece by addition of trace impurities such as cobalt, tantalum, nitrogen, boron, or the like is used. The production process therefor includes heating a turbine rotor member having the specific composition at a temperature between 980° C. and 1100° C. at a part corresponding to the high-pressure part thereof and at a temperature between 850° C. and 980° C.

Abstract: A flat plate member with gear portion is formed to a predetermined shape by pressing a flat steel raw material having a composition comprising, by weight, 0.10-0.18% C, less than 0.03% Si, 0.60-1.50% Mn, less than 0.020% P, less than 0.013% S, 0.001-0.004% B and the balance Fe with inevitable impurities, wherein quenching is performed on only the gear portion.

Abstract: A vehicle structural beam, such as a door intrusion beam, which possesses an elongate tubular beam part which at opposite ends is provided with mounting flanges for securement to a vehicle frame. The elongate tubular beam part and the flanges provided at opposite ends are defined by an integral, one-piece, monolithic steel structure which has been initially roll-formed from an elongate flat metal sheet to define the closed tubular structure of the tubular beam part, and which has been subjected to heating and quenching so that the elongate tubular beam part is of relatively high strength steel throughout its entire length, whereas the integrally and monolithically joined end flanges remain as lower strength steel which has been significantly unaffected by the heat treatment and quenching so as to permit appropriate shaping thereof and ease of welding to the vehicle frame.

Abstract: In a surface processing method for removing surface flaws, surface contaminants, and the like from a continuously cast metal product in a hot state, at least a portion of at least one metal product surface is cooled for a defined temperature decrease of a surface to be treated and a surface treatment is then performed. The device therefor has a cooling device for cooling at least a portion of at least one metal product surface for a defined temperature decrease of a surface to be treated and a surface treatment device downstream of the cooling device in the product conveying direction. The production arrangement for this has a continuous slab casting device, a heating arrangement with at least one of a heating device and a temperature equilibration device arranged downstream of the casting device. A hot mill train is arranged downstream of the heating arrangement in the conveying direction.

Abstract: A carbon steel screw has one or more portions which have been selectively hardened by selective heat treatment and quenching. In one embodiment, an upper portion of the screw head is selectively hardened to prevent or reduce damage when torque is applied using a driving tool. In another embodiment, the screw tip is selectively hardened for more effective penetration into a substrate. Preferably, the selectively heated portions are selectively quenched to reduce or avoid distortion.

Abstract: In a heat treatment method for producing boundary layer-hardened long products and flat products of unalloyed or low-alloy steel, the workpiece is cooled for producing a martensitic grain within a boundary layer of the workpiece by repeating several sequential cooling process steps. Each sequential cooling process step has a cooling phase, in which the workpiece is cooled to a temperature below a martensite starting temperature for martensitic conversion of only a portion of the boundary layer of the workpiece, and a temporal stress-relief phase for relieving stress within already formed martensitic grain areas and already formed martensite/austenite boundary areas. Subsequently, the workpiece is cooled at a cooling rate below a lower critical cooling rate for cooling the workpiece core.

Abstract: An apparatus and a method for suppressing growth of an oxide film on a coil which is a spirally wound, rolled strip are disclosed. A rolled strip subjected to rolling by hot rolling equipment is wound spirally by a down-coiler to make a coil. Covers are disposed on the opposite sides of the coil such that heat resistant materials intimately contact the opposite sides of the coil. The covers are fixed by L-bolts and nuts to cover the opposite sides of the coil with the covers. In this state, the coil is naturally cooled for a predetermined time to suppress growth of an oxide film and increase productivity.

Abstract: A selectively hardened nail includes a nail head, an elongated shank, and a tip. A portion of the nail shank is made harder than the remainder by selectively heat treating that portion, and cooling it. The nail has controlled bending properties. The selectively hardened portion does not significantly bend when the nail is fired at a surface using a power driving tool, or during use of the nailed object.

Abstract: An apparatus and method for excluding specific areas of a workpiece from quenching during a heat treat process. A workpiece, having preselected areas to be quenched, is positioned in a manner so that quench sprays are aimed toward the surface to be quenched. The area to be excluded from the quench is protected by a shroud, and steam is forced under the shroud during the quenching operation. Steam pressure within the shroud is maintained at a pressure sufficient to prevent the quench media from passing through a sealed edge of the shroud. The steam has a temperature sufficient to prevent a sudden drop in the workpiece temperature in the area protected from the quench media.

Abstract: In an apparatus that rapidly cools heat treated metal strips with a recirculating nitrogen-hydrogen cooling gas mixture having a hydrogen content which ranges between 15%-50%, and a recirculation circuit for the gas mixture having a fan for creating a flow though recirculation ducts connected, through expandable compensator corrugations, upstream to at least one gas/water exchanger, a safety system operates with the exchanger. The safety system includes a housing having a main flow area upstream of the exchanger and into which recirculating cooling gas flows. A first register is interposed across the main flow area for selectively switching between open and closed states thereby passing or blocking flow through a major portion of the main flow area. At least one bypass flow area is defined within the housing and located adjacent the main flow area.

Abstract: A method of cooling section steel, particularly sectional steel girders, from rolling heat, wherein, prior to a final air cooling, a water cooling process is carried out in such a way that section steel portions with material concentrations are cooled at outwardly projecting portions of the steel sections over a width of application and a duration of application which are variable and subject to a predetermined cooling strategy supported by a process computer to a value which is at least still slightly above the transformation temperature Ar1.

Abstract: A press-formed article has a quenched area and a required strength distribution. The quenched area has a hardness distribution exhibiting a hardness transition which corresponds to the required strength distribution. The press-formed article may include one end portion, the other end portion, and a central area disposed between the one end portion and the other end portion. The quenched area is extended from the one end portion and to the other end portion. The hardness distribution of the quenched area exhibits a condition that hardness is the highest in the central area in such a manner that hardness is gradually decreased from the central area to the one end portion and to the other end portion.

Abstract: A specialized induction facility provides localized heating in only the desired wear areas of a crane wheel while leaving the supporting material "as-forged" and ductile. The wear area of a crane wheel is hardened such that flanges extending out from a working tread surface are not completely through hardened.

Abstract: A method for drawing a portion of metallic material having a known hardness. The method includes the step of applying a localized heat treatment to predetermined portions of the metallic material. Additionally, the method comprises forming the localized heat treated regions into a desired drawn or stamped configuration, wherein the configuration is substantially devoid of cracks.

Abstract: A steel machine component, such as a bearing race, has a critical surface of generally circular configuration. Here the steel of the machine component exists in a state of compression to improve the physical characteristics of the surface. To this end, high speed steel is melted along the full circumference of the surface. Upon cooling to room temperature some of the austenite in the steel transforms into martensite. Tempering converts much of the remaining austenite into martensite, so that the machine component at the surface is almost entirely martensite. Martensite normally occupies a greater volume than austenite, but since the layer of martensite so formed is confined by the underlying core of the machine component, the layer exists in a state of compression. The high speed steel is melted with a laser beam that makes a trace over the full surface of the machine component.

Abstract: The stamped-metal clip is suitable for use with an endless track belt cooperating with slide rails. The clip comprises a main portion having a hardened bearing surface to be engaged against at least one of the slide rails. The bearing surface has a hardness greater than 35 HRC, preferably between 40 and 60 HRC. The clip further comprises an unhardened fastening portion comprising two curved wings to clamp the main portion to the track belt without rupture. These curved wings have a hardness smaller than the hardness of the bearing surface, preferably smaller than 35 HRC. The hardness of the bearing surface makes it resistant to wear and friction and the smaller hardness of the wings enables the clip to be clamped to the track belt without rupture.

Abstract: A thermocouple formed of a length of a single composition having first solid phase section adjoining a second solid phase section, and a transition therebetween. One method of making such thermocouples is to raise the temperature of the first solid phase section above its transformation temperature while maintaining the temperature of a second adjoining solid phase section of the length of material below its transformation temperature. A second method includes rapidly solidifying a molten material by contacting it with a moving substrate formed of adjoining regions of differing thermal conductivity. A third method includes rapidly solidifying a molten material by alternatingly contacting it with a cooling fluid and air. A fourth method includes transforming a section of a length of material in a first solid to a second solid phase by mechanical means.

Abstract: A method of thermal or thermochemical treatment of precision steel components having different wall thicknesses comprising the steps of a) hardening (8), b) low temperature cooling (9) and c) annealing (10), wherein the precision steel components are subjected to a low temperature cooling of only selected parts of the precision steel component to effect a reduction in the occurrence of primary residual austenite in the selected parts thereof.

Abstract: A process for selectively hardening a forged track chain link has the following steps. A forged track chain link having a pad portion, a rail portion, a first side portion and a second side portion, is provided. A quench tank is provided and adapted for spraying one or more of the track chain link portions with a quenchant at a controlled amount of quenchant flow rates, quenchant pressures and quench times. One or more of the track chain link portions are sprayed with the quenchant at a controlled amount of one or more of a plurality of quenchant flow rates, a plurality of quenchant pressures and a plurality of quench times. The pad and rail portions are simultaneously hardened to predetermined respective hardnesses.

Abstract: Thermal insulating gaseous blankets, generated by contact of a quench liquid with a hot metal workpiece, are displaced from downwardly directed surfaces by sequentially elevating the workpiece, at points about its periphery, so as to promote migration of the trapped gas across such surfaces. The improved heat transfer that results increases the levels of hardness and strength exhibited by the treated workpiece.

Abstract: Compressive residual stresses can be developed by underwater plasma transferred arc welding. The development of these compressive stresses act to prevent hot cracking and He embrittlement that can develop during welding or stress corrosion cracking that can develop subsequent to the welding operation.

Abstract: The invention relates to a method for fabricating a piece of structural steel that includes thermal or thermomechanical treatment steps that could ordinarily lower the fatigue strength and shock and impact resistance of the steel piece. In the method of the invention a workpiece of microalloy steel is fabricated containing the following elements in the mounts indicated and having a bainitic structure:______________________________________ C 0.05-0.5 wt. % Mo 0-0.5 wt. % Mn 1-2 wt. % V 0-0.30 wt. % Si 0.05-1.5 wt. % B 0-0.010 wt. % Cr 0.1-1 wt. % Ti 0-0.030 wt. % Nb 0-0.1 wt. % ______________________________________The workpiece is then subjected to a treatment that includes a heating stage wherein at least a part of said piece is subjected to a temperature in the range 500.degree.-900.degree. C., followed by a cooling stage in which at least the part of the piece is subjected to cooling at a rate greater than 500.degree. C./hr.

Abstract: Low temperature water in a low temperature water tank 12 installed outside a reactor pressure vessel 9 is pumped by a high pressure pump 15 and supplied through a conductor 17 under pressure. The supplied water is ejected, as a stream of cold water jet 8, from a nozzle 14 connected to the conductor 17 and introduced into the reactor pressure vessel 9 by a driving mechanism. The stream of cold water jet 8 ejected from the nozzle 14 is directed to impinge against a predetermined position of a core shroud 13 in reactor water 11 filled in the reactor pressure vessel 9 and being at temperature higher than the low temperature water. Then, while continuing to eject the cold water jet 8 from the nozzle 14, the nozzle 14 is moved away from the predetermined position, or the ejection of the cold water jet 8 from the nozzle 14 is stopped, allowing the predetermined position to be heated again with the temperature of the reactor water 11.