process for preßstumpfschweißen of track links made of steel

摘要

Method of pressure butt welding of chain links is described in which heat treatable steels contg. 0.15% C and 0.5% Cr can be used to produce high strength chains. The process comprises two steps, in the first of which the surface faces to be joined are smoothed by application of a forging current of 0.5kA/mm2 lasting two periods together with a compressive stress on the surfaces in contact of 45 kp/mm2. The second step comprises application of an initial welding current of 0.75 kA/mm2 while a pressure of 40kp/mm2 is reached over 4 periods, due account being taken of the kinematics of the mechanical-hydraulic drive of the chain welding machine, so that no sweating out of liq. phase occurs from the joint. Oxide formed on the surface of the steel during welding does not become emulsified with the liq. metal in the joint, hence the oxide does not penetrate the joint to cause weakening.