METHOD FOR JOINING METALLIC MATERIALS BY DIFFUSION BONDING AND JOINED STRUCTURE THEREBY

摘要

A method for obtaining a welded portion having a fatigue resistance and a mechanical strength or for obtaining a welded portion having a corrosion resistance and a mechanical strength in a wet carbonic acid gas environment containing a little amount of hydrogen sulfide. (1) A method of welding metal materials by interposing a low-melting welding material (welding material) between base metals, heating the welded portion inclusive of the welding material, so that the length heated at not lower than 800 ~C is 3 to 20 mm, and applying a compression stress in the lengthwise direction indicated by arrow (5) so that the welded portion is plastically deformed at a lateral bulging ratio of 1.0 to 1.1. Its welded structure is also disclosed. (2) A welding method wherein the base metal is a stainless steel containing not less than 9 % by weight of Cr, the joining material is an Ni-based alloy containing not less than 5 % by weight of Cr, and having a melting point of not higher than 1150 ~C and a thickness of 10 to 80 .mu.m, the pressure is 0.5 to 2 kgf/mm2, the length heated at not lower than 800 ~C is 3 to 20 mm, and the welded layer is heated at a temperature not lower than the melting point of the welding material but not higher than the melting point of the base material for more than 120 seconds. Its welded structure is also disclosed. (3) A method in which limitation is imposed on the joining material, the pressing method and the atmosphere of either of the methods (1) and (2).