Additive manufacturing (AM) development necessitates pushing technological boundaries more and more. This is particularly true in the case of metal powder AM. The fabrication characteristics and environment, notably the high temperature gradients and complex atmosphere, make process monitoring difficult. Indeed, this is a significant hurdle for research and development in the field. In this context, a novel device consisting of a continuous wave fibre laser coupled with an environmental scanning electron microscope (ESEM) has been developed as a powerful tool for AM research. This equipment combines a laser capable of reproducing both laser powder bed fusion and laser metal deposition (LMD) conditions (varying power, scan speed and spot size) and a versatile ESEM with secondary electron (SE), backscatter electron (BSE), electron backscatter diffraction (EBSD) and thermal characterisation features [1].

Thanks to the use of this unique device, a slew of different processing and characterisation experiments can be performed. An example is presented in the form of LMD 316L mechanical behaviour enhancement. The laser SEM treatment refined the characteristic AM cellular microstructure by an order of magnitude, as imaged by SE and BSE. This microstructure refinement led to significant strength and ductility improvement. Indeed, the yield strength is significantly increased without loss, but rather also increase, of ductility. The EBSD data also point towards crystallography tailoring possibilities. In fact, the laser SEM can bring different texturisation of previously non textured material. Furthermore, the obtained results are very promising for the modelling and simulation, fatigue research and welding fields [2].

References

[1] A. Tanguy, M. Upadhyay, J.G. Santos Macías; System for continuous wave laser treatment and SEM characterisation of a sample, France, 2022, Pending, 20.

[2] J.G. Santos Macías, A. Tanguy, S. Hallais, M. Upadhyay; Continuous wave fibre laser - environmental scanning electron microscope coupling. Use for strength enhancement without ductility loss via post process laser scanning of 3D printed stainless steel, 2023, To be submitted.