Abstract
JIS class 2 titanium of φ 2mm wiry specimens was welded by 4 types of welding methods. Strength of the welding regions was assessed by tensile tests of these specimens. Methods of welding were laser welding (A) and Tig weIding (B) both with provisional joining by laser welding. Each of these weldings was carried out under two conditions. One was direct welding, in which the surfaces were tightly fixed to direct contact. The other condition was indirect welding, in which the jointing surfaces were tightly fixed intermediate material consisting of a round Titanium plate φ 0.25mm thick. For Laser welding, Nd Yag Laser welding-machine (Dentaurum Co., DL 2000) and for the Tig welding, a conventional Tig welding-machine Inverter (Hitachi Co., Tig 300 NSII) in the Titanium casting machine were respectively used. The highest welding strength with small deviation was observed in the group treated by direct laser welding. In the Tig welding group, there was no significant difference in the strength between direct and indirect welding. There was no significant difference between Tig welding groups and indirect laser welding. It was suggested that jointing surfaces cut rectangularly should be tightly fixed with a jig for the elimination of transverse distortion during the welding procedure. These results may indicate that more amount of molten titanium pool flows under Tig welding than under the laser welding. Tensile strength of the welded region after laser welding was generally higher and more constant than that achieved by the Tig welding.
