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- Welding (3) (entfernen)
Single-pass solid-state laser welding of plates in the thickness range of 10 to 20 mm became
possible with the invention of the fibre laser. This new technique provides excellent beam
quality at powers as high as 20 kW or more, and has proved applicable in several industrial
applications. By replacing conventional methods with the fibre laser, it is possible to avoid
multiple-pass welding that requires time-consuming bevelling. The high energy density of the
fibre laser beam also reduces the heat input and consequently the distortion. However, the
rapid solidification and cooling associated with laser welding can cause imbalance of the
microstructure of duplex stainless steel weldments, where excessively high ferrite contents
may reduce the corrosion resistance and the ductility of the material. The solution is normally
to add nickel-based filler wire and to increase the heat input. By using a hybrid welding
process where the laser beam and the gas metal arc (GMA) process act in a common
process zone, filler metal can be added to the molten pool at higher heat input and at the
same time, higher welding speed and deeper penetration can be achieved. In this work,
13.5 mm thick 2205 (EN 1.4462, UNS S31803) was fibre laser-GMA hybrid welded in a
single-pass using 14 kW of laser power and 2209 (ISO 22 9 3 L N) as filler wire for the GMA
process. The resulting welds were free from defects, with smooth surfaces and full
penetration. The investigation examines the weld metal microstructure and the effect on
corrosion resistance and mechanical properties. The option to add nickel foil when hybrid
welding was also investigated as comparison and the effect on austenite formation was
evaluated.