Abstract: A high-strength flexible shaft coupling comprises a plurality of concave annular diaphragms of sheet metal, each of substantially constant and equal thickness in radial cross-section, arranged in series upon a common axis with their concavities alternately facing in opposite axial directions. Adjacent diaphragms are joined together by electron beam welding at their respective radially inner or outer margins, and means are joined by electron beam welding to the radially inner or outer margin of those diaphragms which are at each axial end of the plurality for connecting the coupling to respective shafts. One class of example is directed to separating radial bending stresses from the welded areas in order to reduce fatigue effects and increase load-bearing capacity.