| 摘要 |
PROBLEM TO BE SOLVED: To provide a tube to be used for a heat exchange tube for high temperature gas furnace which has a high melting point, high oxidation resistance or the like, and is provided with good weldability. SOLUTION: This heat exchange tube has a tube base body (11), tube edge part (13) as joint forming parts and transition parts (12) connecting the tube base body to the edge fringe parts, the base body (11) consists of a Cr-Fe series alloy having a Cr content of 60 wt.% or more, the tube edge part (13) consists of easily weldable metal, and the tansition part (12) is a multilayer structure consisting of metal having a gradient composition in which the ratio of the mixing quantity of easily weldable metal/a Cr-Fe series alloy is gradually increased from the substrate side toward the tube edge part side. As the easily weldable metal, stainless steel or the like are exemplified. Metal powder prepared to a prescribed composition is charged into a capsule in a laminated manner, and is subjected to a hot isostatic pressing formation to produce the tube.
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