Abstract: A low-temperature joining method effectively suppresses reductions in the mechanical properties of a junction of various types of high-tensile steel or aluminum, and of a heat-affected zone; and produces a joint structure. A method for joining two metal materials by forming a joint interface in which the two metal materials face each other at a joint portion and plunge a rotation tool caused to rotate at a prescribed speed into the joint, the method for low-temperature joining of metal materials characterized in that the peripheral velocity of the outermost periphery of the rotation tool is set to 51 mm/s or less, whereby the recrystallization temperature inherent to the metal materials is reduced by introducing a large strain to the joint, and recrystallized grains are generated at the joint interface by setting the joining temperature to less than the recrystallization temperature inherent to the metal materials.

Abstract: A linear friction welding method capable of accurately controlling a welding temperature and capable of lowering the welding temperature is provided. The present invention is a linear friction welding method comprising: a first step of forming a welded interface by bringing one member into contact with the other member; a second step of repeatedly sliding one member and the other member on the same locus and discharging flash from the welded interface in a state where pressure is applied substantially perpendicularly to the welded interface; and a third step of forming a welded surface by stopping the sliding and setting the pressure to be not less than the yield stress and not more than the tensile strength of one member and/or the other member at a desired welding temperature.

Abstract: To provide a solid phase welding method and a solid phase welding apparatus which are possible to accurately control the welding temperature, to lower the welding temperature and to achieve a solid phase welding of the metallic materials. The present invention provides a solid phase welding method for metallic materials comprising, a first step of forming an interface to be welded by abutting end portions of one material to be welded and the other material to be welded and applying a pressure in a direction substantially perpendicular to the interface to be welded, a second step of raising a temperature of the vicinity of the interface to be welded to a welding temperature by an external heating means, wherein the pressure is set to equal to or more than the yield strength of the one material to be welded and/or the other material to be welded at the welding temperature.

Abstract: The present invention provides a friction welding method capable of reducing the welding temperature and a friction welding method capable of obtaining a welded portion free of defects regardless the type of material. A frictional welding method in which one member is brought into contact with the other member and slides while a load is applied substantially perpendicularly to the interface to be welded, the frictional welding method comprising: a first step in which frictional welding is carried out by setting a pressure calculated from the area and the load of the interface to be welded to be equal to or higher than the yield stress and the tensile strength of one member and/or the other member at a desired welding temperature; and a second step in which frictional welding is carried out by lowering the load, wherein the first step and the second step are continuously carried out.

Abstract: The friction stir welding tool member according to the present invention is made of a ceramic member in which a shoulder portion and a probe portion are integrally formed, wherein a root portion of the probe portion and an end portion of the shoulder portion have a curved surface shape; and the friction stir welding tool member has a ratio (R1/D) of 0.02 or more and 0.20 or less when a curvature radius of the end portion of the shoulder portion is defined as R1 (mm) and an outer diameter of the shoulder portion is defined as D (mm). In addition, the ceramic member is preferably made of a silicon nitride sintered body having a Vickers hardness of 1400 HV1 or more. According to the above-described configuration, a friction stir welding tool member having excellent durability can be provided.

Abstract: The friction stir welding tool member according to the present invention is made of a silicon nitride sintered body, wherein the silicon nitride sintered body contains 15% by mass or less of additive components except silicon nitride in such a manner that the additive components include at least one element selected from lanthanoid elements and at least one element selected from Mg, Ti, Hf, and Mo. In addition, it is preferable that the additive components further include at least one element selected from Al, Si, and C. According to the above-described configuration, a friction stir welding tool member having an excellent durability can be provided.

Abstract: Provided are a simple and effective friction welding method that can suppress increases in hardness of the welded part and reductions in hardness (strength) in the heat affected zone regardless of the composition of ferrous material, and a welded structure obtained with the same. The present invention relates to a friction welding method wherein surfaces to be welded of two metal members (2, 4) to be welded are made to slide in contact with each other. The friction welding method is characterized in that at least one of the metal members (2, 4) to be welded is a ferrous material, and the maximum temperature reached during welding is equal to or less than the A3 point or equal to or less than the Acm point of the ferrous material. The maximum temperature reached during welding is preferably equal to or less than the A1 point of the ferrous material.

Abstract: A base material of a ferrous material is heated to an AC1 point, which is a temperature to cause austenite appearance, or higher, and austenite appears in the base material 1a and 1b (S101). An amount of a strain assuming that an Mf point, which is a temperature where the base material becomes martensite completely, is decreased to be less than room temperature is introduced into the base material (S102). The all ferrous material becoming martensite on the occasion of cooling the ferrous material to room temperature is prevented. The base material is cooled to room temperature at a cooling rate where a line extrapolated a cooling curve of the base material intersects with a region where martensite is produced on the CCT diagram (S103). Austenite remains in the manufactured ferrous material at room temperature.

Abstract: A welding method in which an inert gas is supplied to the surface of an iron material from inside a cylindrical welding nozzle, and the surface of the iron material to which the inert gas is being supplied by the welding nozzle is heated, wherein oxygen in the atmosphere sucked by a drop in atmospheric pressure caused by the flow of the inert gas is introduced into a molten pool produced in the surface of the iron material. Consequently, it is possible to make the depth of penetration of the molten pool deeper by introducing oxygen into the molten pool and increase welding efficiency without preparing an additional oxygen supply source as in dual shield TIG welding.

Abstract: There is provided a tool for friction stir welding, in which a coating layer is less likely to peel off from a base material and excellent wear resistance is achieved. The tool for friction stir welding according to the present invention includes a base material (BM) and a coating layer. The BM includes a first hard phase (FP) formed by WC particles, a second hard phase (SP) and a binder phase (BP). The SP is formed by a compound of one or more metals selected from Ti, Zr, Hf, Nb, Ta, Cr, Mo, and W and one or more elements selected from nitrogen, carbon, boron, and oxygen, and is included in the BM at a volume ratio of 3% to 30%. The BP is included in the BM at a volume ratio of 8% to 28%. The FP is higher than the SP in terms of volume ratio.

Abstract: There is provided a tool for friction stir welding having excellent wear resistance and chipping resistance. The tool for friction stir welding according to the present invention includes a base material, the base material includes a first hard phase, a second hard phase and a binder phase, the first hard phase is formed by WC particles, the second hard phase is formed by a compound of one or more metals selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W and one or more elements selected from the group consisting of nitrogen, carbon, boron, and oxygen, or a solid solution of the compound (except for WC), the binder phase is formed by an iron group metal, and the second hard phase is higher than or identical to the first hard phase in terms of volume ratio.

Abstract: A base material of a ferrous material is heated to an AC1 point, which is a temperature to cause mustenite appearance, or higher, and austenite appears in the base material 1a and 1b (S101). An amount of a strain assuming that an Mf point, which is a temperature where the base material becomes martensite completely, is decreased to be less than room temperature is introduced into the base material (S102). The all ferrous material becoming martensite on the occasion of cooling the ferrous material to room temperature is prevented. The base material is cooled to room temperature at a cooling rate where a line extrapolated a cooling curve of the base material intersects with a region where martensite is produced on the CCT diagram (S103). Austenite remains in the manufactured ferrous material at room temperature.

Abstract: There is provided a tool for friction stir welding having excellent wear resistance and chipping resistance. The tool for friction stir welding according to the present invention is a tool for friction stir welding used in friction stir welding processing, wherein the tool for friction stir welding includes a base material, the base material includes a first hard phase and a binder phase, and has a thermal conductivity of 45 W/m·K or less, the first hard phase is formed by WC particles, and the binder phase is formed by an iron group metal and is included in the base material at a volume ratio of 8% by volume or more and 28% by volume or less.

Abstract: There is provided a tool for friction stir welding having excellent wear resistance and chipping resistance. The tool for friction stir welding according to the present invention is a tool for friction stir welding used in friction stir welding processing, wherein the tool for friction stir welding includes a base material, the base material includes a first hard phase and a binder phase, and has a thermal conductivity of 45 W/m·K or less, the first hard phase is formed by WC particles, and the binder phase is formed by an iron group metal and is included in the base material at a volume ratio of 8% by volume or more and 28% by volume or less.

Abstract: There is provided a tool for friction stir welding, in which a coating layer is less likely to peel off from a base material and excellent wear resistance is achieved. The tool for friction stir welding according to the present invention includes a base material (BM) and a coating layer. The BM includes a first hard phase (FP) formed by WC particles, a second hard phase (SP) and a binder phase (BP). The SP is formed by a compound of one or more metals selected from Ti, Zr, Hf, Nb, Ta, Cr, Mo, and W and one or more elements selected from nitrogen, carbon, boron, and oxygen, and is included in the BM at a volume ratio of 3% to 30%. The BP is included in the BM at a volume ratio of 8% to 28%. The FP is higher than the SP in terms of volume ratio.

Abstract: There is provided a tool for friction stir welding having excellent wear resistance and chipping resistance. The tool for friction stir welding according to the present invention includes a base material, the base material includes a first hard phase, a second hard phase and a binder phase, the first hard phase is formed by WC particles, the second hard phase is formed by a compound of one or more metals selected from the group consisting of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, and W and one or more elements selected from the group consisting of nitrogen, carbon, boron, and oxygen, or a solid solution of the compound (except for WC), the binder phase is formed by an iron group metal, and the second hard phase is higher than or identical to the first hard phase in terms of volume ratio.

Abstract: The present invention provides a method of forming a metal coating having a microstructure as well as a structural member having a metal coating formed by the method. In particular, the invention provides an advantageous method of forming a metal coating in which minute carbides are uniformly dispersed. The method of forming the metal coating of the present invention includes the steps of cladding a surface of the substrate with metal powder by a laser cladding method and forming the metal coating having a microstructure by applying a friction stir processing to the cladded region.

Abstract: Provided are a method of modifying a cemented carbide and a cemented carbide modified by the method. Particularly provided is an advantageous method of modifying a cemented carbide layer formed by a thermal spraying method on a surface of a metal substrate. The method of modifying a cemented carbide includes applying a friction stir process to a cemented carbide, thereby allowing crystal grains in a binder phase included in the cemented carbide to become finer. It is possible to achieve modification effectively by applying the friction stir process particularly to a cemented carbide layer formed on a surface of a metal substrate by using the thermal spraying method.

Abstract: A method for refining the texture of a ferrous material. The method includes a first step and a second step. The first step includes a step of making carbide particles in a portion of a base material smaller. The second step includes a step of nitriding at least a part of said portion.

Abstract: In a first step, friction stir welding is performed, while supplying a filler into a joining portion, in order to prevent the coarsening of crystal grains of metal materials in a subsequent fusion processing. Then, a fusion processing such as MIG welding is performed. The filler to be added to the joining portion includes a substance that does not chemically react with the metal materials and has a melting point higher than a melting point of the metal materials and a substance in which a misfit with the metal materials is within ±15%. As a result, the coarsening of crystal grains by the fusion processing is inhibited and the joint strength can be increased.