| abstract |
A zinc coated steel work piece 4 is prepared for welding by scanning with laser radiation 2, to remove the zinc coating layer. The laser has a wavelength in the range of 150 nanometres to 20 micrometres, at a fluence of 0.1 to 100 Joules per square centimetre, with a pulse length in the range of 1 nanosecond to 10 microseconds and for a minimum of 1 pulse, preferably at least 10 pulses, at each laser radiation impact point on the surface. The laser is preferably an eximer laser. The prepared surface of the work piece can then be welded to a further work piece by resistance spot welding, arc welding, friction welding or laser welding. For laser welding a laser is used, preferably operating at a power of substantially 750 watts at a scan rate of substantially 240 millimetres per minute in an atmosphere of nitrogen. <IMAGE> |