The components to be welded are rigidly clamped in the MIAB welding equipment, leaving a predetermined, small gap between their ends. In the first stage of the process, a DC arc is struck between the component ends. A static, radial magnetic field causes this arc to travel at high speed around the joint circumference, heating the component ends to a high temperature (see Fig. 1).
Heating continues for a few seconds then, in the second stage, the components are brought together under a predetermined forging pressure (see Fig. 2). Any molten material is expelled from the joint and a solid phase weld is produced.
The components do not rotate during the process. No filler material or shielding gas is used and MIAB welding produces very little fume.
Low and medium carbon steel and low alloy steel are routinely MIAB welded. Production applications include drive shafts, propeller shafts, beam axles, axle casings, refrigerator condenser tubes, pressure accumulators and petrol tankfiller spouts.
Wall thickness from 0.6mm to 10mm and cross sections up to 2000mm 2 have been successfully MIAB welded at TWI. MIAB welding studies have included aluminium alloys, stainless steels and titanium alloys.