A preliminary test of a novel molten metal filler welding process

A novel welding process named molten metal filler welding aimed to control heat input precisely was investigated in this paper. The process used molten metal which was high in both speed and temperature as a heat source. The filler metal was heated to a temperature above the melting point preliminary at a graphite crucible. The molten filler metal was jetted as a flow by pressure to achieve a big depth-to-width ratio of bead. A new welding system was designed to fulfill the requirements of the process. The relation between the flow speed and the input pressure was calculated. Tests using tin-lead alloy (63 % Sn-37 % Pb) plates showed that the distance between the nozzle and workpiece had an important influence on the joint quality. When the distance was 2 mm or less, an ideal joint could be obtained. The penetration increased with the heat input proportionally, and increasing input pressure was the most efficient way to increase penetration. The weld profile was mainly affected by the travel speed. A novel conception to limit the flow of the weld pool was proposed. If the weld pool flowed in a limited space, it was easy to get an ideal joint in which the depth-to-width ratio could reach 6. Meanwhile, the heat distribution of the process could be investigated using the microstructures of the samples.