The nickel mesh and nickel sheet of a nickel hydrogen battery fuse with each other. Lithium batteries, polymer batteries, copper foil and nickel sheets are fused together, while aluminum foil and aluminum sheet are fused together. Electric wires fuse with each other, forming one or more wires that fuse with each other, and wiring harnesses are welded. Electric wires fuse with various electronic components, contacts, and connectors. The mutual melting of large heat sinks, heat exchange fins, and honeycomb cores for various household appliances and automotive products. High current contacts such as electronic component leads, relays, electromagnetic switches, and non fused switches, as well as mutual melting of dissimilar metal sheets. The sealing, cutting, and sealing of metal pipes can be water tight and airtight.