The role of both laser pulse length and duty cycle in controlling the grain size and crystallographic texture of diode laser-deposited Waspaloy powder is investigated. Thin-walled test structures of Waspaloy have been produced using a range of pulse parameters and analyzed by means of scanning electron microscopy and electron backscatter diffraction. Results have been correlated with a simple analytical model of the effect of the laser pulse on the substrate temperature and melt-pool geometry in order to help explain the trends observed. Findings show that pulse parameters have a marked effect on the resulting grain morphology and crystallographic orientation. Modelling has indicated that this arises because the microstructure is highly dependent on the melt-pool geometry, particularly the inclination angle of the melt-pool boundary.
- Electron backscatter diffraction
- Laser direct metal deposition (LDMD)
- Near-net shape manufacture
- Nickel alloys