1. Field of the Invention
The present invention relates to a friction stir tool.
2. Description of Related Art
There exists a friction stir welding method which conducts welding by inserting a cylindrical member formed of a material which is substantially harder than materials to be joined (hereinafter the cylindrical member is referred to as rotational tool, stirring tool or friction stir tool. Or it is also referred to simply as welding tool.) into a joined part of the materials to be joined while rotating the cylindrical member, rotating and moving this rotational tool at the same time to join the materials to be joined by the frictional heat generated between the rotational tool and the materials to be joined.
Japanese Patent No. 2712838 (Patent Document 1) discloses a friction welding method for joining workpieces (1A, 1B) in a joint region (2), in which a probe (3) of material harder than the workpiece material is inserted into the joint region (2) and opposed portions of the workpieces on both sides of the joint region to cause relative cyclic movement between the probe and the workpieces so that frictional heat is generated to cause the opposed portions to take up a plasticized condition; the probe (3) is removed; and the plasticized portion is allowed to solidify and join the workpieces together, whereby the workpieces are joined without relative movement between themselves. This joining method involves softening the materials to be joined by the frictional heat between the rotational tool and the materials to be joined and utilizing the plastic flow phenomenon caused by the rotation of the rotational tool, and is based on a principle different from a method of welding by dissolving the materials to be joined, for example, arc welding and the like.
JP-A-2008-36664 (Patent Document 2) discloses a friction stir welding tool which has a cylindrical body of revolution and a probe coaxially projecting from a shoulder on its end face, and joins a pair of joined members by rotating the probe and inserting it into the joined parts of the joined members where they are abutted so that the joined part is softened by the frictional heat generated and stirred, in which the probe and the body of revolution are attachable and detachable, and the probe is formed of a cemented carbide or a cobalt-based alloy copper (MP159).
JP-A-2005-152909 (Patent Document 3) discloses a rotational tool for a friction stir welding for integrating a joined part of metal pieces by a friction stirring, in which a deposition prevention film for preventing deposition of a joining material metal on a surface of a portion which comes into contact with the metal.
JP-A-2004-82144 (Patent Document 4) discloses a friction stir welding tool which is made of a material harder than a workpiece made of metal and is rotated, pressed and inserted into an abutment portion of a pair of workpieces made of the metal to join the workpieces made of the metal by friction stirring, the welding tool having a central member formed of metal, and a ceramic member which covers a region of the central member which comes into friction contact with at least the workpieces made of the metal, the ceramic member comprising a nitride of Si, and the central member being a heat-resistant alloy comprising at least one of Fe, Ni, Co and W as a main component.
JP-A-2003-532543 (Patent Document 5) discloses a friction stir welding tool which is capable of joining metal matrix composites (MMCs), ferroalloys, nonferrous alloys and superalloys by friction stir welding, the welding tool comprising a shaft, a shoulder, a pin, and a highly wear resistant material disposed in at least a portion of the shoulder and the pin, the shoulder being mechanically fixed on the shaft to prevent rotary motion of the shoulder with respect to the shaft, the highly wear resistant material having a first phase and a second phase, and being produced at an ultra high temperature under ultra high pressure, functionally allowing friction stir welding of MMCs, ferroalloys, nonferrous alloys and superalloys.
JP-A-2006-320958 (Patent Document 6) discloses a friction stir welding tool which is capable of conducting friction stir welding on a metal or an alloy having a melting point of 1600° C. or higher as a workpiece, and at least a portion of the welding tool which is brought into contact with the workpiece comprising iridium as a main component and rhenium, ruthenium, molybdenum, tungsten, niobium, tantalum, zirconium or hafnium or two or more of these as accessory components, and having a Micro Vickers Hardness of 200 Hv or higher.
JP-A-2005-199281 (Patent Document 7) discloses a friction stir welding tool having a probe pin extending from a tip surface of a rotating rotator which is press-fitted onto a joined part of joined members and moved along this joined part to join the joined members in the joined part by friction stir welding, in which the portions of the probe pin and rotator which come into contact with at least the above-mentioned jointed members are constituted by a WC-based cemented carbide containing Co in an amount of 5 to 18% by weight.
WO2007/032293 (Patent Document 8) discloses Co-based alloy having highly heat resistant and high strength, comprising 0.1-10% of Al, 3.0-45% of W, and Co as the remainder except for inevitable impurities in terms of mass proportion, and has an L12 type intermetallic compound containing [Co3(Al,W)] precipitated therein.