Laser Weld Deposition
The PTA process is easily automated, providing a high degree of reproducibility of the weld overlays. In addition, because of the highly concentrated heat source, this process benefits from high powder utilization and can achieve a very low level of iron dilution in the overlay. Because the hardfacing materials are in powder form, it is possible to produce overlays from many different materials and combinations of materials with a wide range ofhardness and other properties.
When overlaying with a laser, an optical arrangement is used to focus the laser beam on the workpiece and heat it. Simultaneously, hardfacing material in the form of powder or wire is introduced into the laser beam and melted. Due to the narrow heat-affected zone and the fast cooling rate, the heat input is low, thereby producing an almost stress-free overlay. Compared with other welding processes, for a given hardfacing alloy, the fast cooling rate of the laser process produces an overlay with a significantly higher hardness and finer microstructure.