Abstract: The present invention relates to a powder for additive manufacturing, having a composition consisting of, in mass %: 0.25<C<0.40, 0.001?Si?0.15, 0.30?Mn?0.45, 5.0?Cr?5.5, 1.0?Mo?1.5, 0.35?V?0.45, 0.01?N?0.05, 0.01?O?0.04, and optionally, P<0.10, Cu<0.20, Ni<0.20, Al<0.05, Zr<0.05, S<0.20, Pb<0.20, Bi<0.20, Nb<0.20, Ti<0.20, B<0.10, and Co<0.20, with the balance being Fe and unavoidable impurities, in which a surface of the powder for additive manufacturing is coated with an oxide film, and the oxide film has a thickness of 3 nm or more and 30 nm or less.

Abstract: In diffusion bonding a metal pipe 112e and a metal pipe 114e via a bonded interface 116e formed at the end parts, a portion that is inclined with respect to the radial direction of metal pipes 112e and 114e is provided at least at part of bonded interface 116. In this case, the inclination angle &phgr; of bonded interface 116e and the tip angle 2&thgr; of a pipe expansion tool 130 are preferably in the relationship, 0<&phgr;≦&thgr;+60°. In performing pipe expansion of such a metal pipe bonded body 110e, the pipe expansion tool 130 is moved from the metal pipe 112e, at which the inclined portion of junction face 116e is formed to have a protruding shape, towards the metal pipe 114e, at which the inclined portion of junction face 116e is formed to have a recessed shape. Furthermore, the inner diameter at the vicinity of the junction face of the metal pipe junction may be made larger than the inner diameter at positions away from the junction face.

Abstract: The present invention provides a metal pipe bonded body formed from a plurality of metal pipes. Each metal-pipe is formed with an elongated, pre-formed portion at each end, and a central portion, each elongated, preformed portion having a constant inside diameter greater than an inside diameter of the central portion of each metal pipe.

Abstract: Carbon steel pipes are joined to each other in a non-oxidizing atmosphere by using an insert constituted by a Ni-base alloy or a Fe-base alloy having a melting point which is lower than 1200° C. and a thickness of 80 mm or smaller under conditions that the surface roughness Rmax of the joined surfaces of the carbon steel pipes is 20 &mgr;m or smaller, the joining temperature is not lower than 1250° C. nor higher than 1330° C., duration at the joining temperature is 30 seconds or longer and the pressure is not lower than 2 MPa nor higher than 4 MPa. The expanding operation is performed such that the maximum difference in level of the joined portion is not larger than 25% of the carbon steel pipe and the expansion ratio is 25% or lower.

Abstract: In diffusion bonding a metal pipe 112e and a metal pipe 114e via a bonded interface 116e formed at the end parts, a portion that is inclined with respect to the radial direction of metal pipes 112e and 114e is provided at least at part of bonded interface 116. In this case, the inclination angle &phgr; of bonded interface 116e and the tip angle 2&thgr; of a pipe expansion tool 130 are preferably in the relationship, 0<&phgr;≦&thgr;+60°. In performing pipe expansion of such a metal pipe bonded body 110e, the pipe expansion tool 130 is moved from the metal pipe 112e, at which the inclined portion of junction face 116e is formed to have a protruding shape, towards the metal pipe 114e, at which the inclined portion of junction face 116e is formed to have a recessed shape. Furthermore, the inner diameter at the vicinity of the junction face of the metal pipe junction may be made larger than the inner diameter at positions away from the junction face.

Abstract: A method for evaluating bonding properties of a metallic pipe, the method comprises steps of measuring, in advance of a pipe expansion operation, at least one selected from a degree of shape discontinuity, a degree of defect at a bonding portion, and a degree of change in crystal structure, and comparing a measurement value with a predetermined threshold value to evaluate suitability of the bonding properties for applying pipe expansion.

Abstract: A method for examining bonded-metal by ultrasonic examination, the method comprising a step of measuring an attenuation amount of an ultrasonic wave, the ultrasonic wave being generated by a sending probe and received by a receiving probe through a bonding interface, the sending probe and the receiving probe being disposed on the bonded-metal with putting the bonding interface therebetween, the bonded-metal being bonded under unknown condition, and a step of examining a bonding property of the bonded-metal based on the attenuation amount, with utilizing a relationship between a bonding property and an attenuation amount for standard metal bonded under known condition measured preliminarily.

Abstract: In a method of bonding ferric and austenitic dual stainless steels, an insert material made of a Ni base alloy having a melting point below 1290.degree. C. is put between the bonding cross section faces of mother material steels comprising a dual phase stainless steel. A pressure force in the range of 3 MPa to 5 MPa is applied to a bonding area. The bonding area is heated at a temperature in the range of 1290.degree. C. to a melting point of the mother material steel. The temperature is kept for in the range of 30 second to 180 second.

Abstract: A method of firmly jointing Ti-alloy members of various shapes such as pipes and rods by solid diffusion bonding. The members are butted and heated under pressure in a non-oxidizing atmosphere, while a Ti-layer is disposed at the interface of butting by either (1) inserting a sheet for bonding made of Ti having a thickness of 500 .mu.m or less between the butted faces, or (2) previously forming a Ti-layer for bonding having a thickness of 1 .mu.m or more on at least one of the butted faces by any method such as vapor deposition.