Tensile Properties of Electron-Beam-Welded Mo-Nb, Mo-Zr and Mo-Re Alloys

Abstract

Tensile properties of electron-beam-welded pure molybdenum, MO-0.4%Nb, Mo-0.05%Zr and Mo-5%Re alloys were measured at -70°C and 20°C. Furthermore effects of a small amount of alloying elements on the ductility of weldments were discussed from the structural points of view (grain size, precipitate size and distribution).
The results were summarized as follows.
(1) The strengths of EB-welded Mo-Nb and Mo-Zr alloys were enhanced compared with those for EB-welded pure molybdenum. However the ductilities of these alloys were only slightly improved. The strengths of EB-welded Mo-Re alloy were reduced, in contrast. However its ductility was relatively improved.
(2) Postweld recrystallization induced marked reduction of strengths of the weldments, except for the fracture strength of EB-welded Mo-Re alloy. The ductility of the weldments were appreciably improved by the postweld recrystallization.
Above results were reasonably interpreted from the differences in grain size, precipitate size and distribution, and from the softening effect by Re addition.