Influence of an Electromagnetic Compound Field (EMCF) on Defect Reduction in Laserdirected Energy Deposition (LDED) Inconel 625 Clads
X-L. Wang, J-K. Jiang and Y-C. Tian
Laser-directed energy deposition (LDED) has the advantages of high material utilization, high degrees of freedom and high forming efficiency; consequently, it is applied widely in surface enhancement and repair of damaged parts. There are, however, some defects in the deposition process such as cracks and pores. The assistance of the external energy field is an effective measure to reduce such defects. To study this we deposited a single track clad of Inconel 625 onto the surface of HT300 grey cast iron by laser-directed energy deposition (LDED) with electromagnetic compound field (EMCF) assistance. The geometrical characteristics, microstructure and microhardness of the clad were determined to investigate the influence of the EMCF. The results show that: under the action of the EMCF with high magnetic field strength and high pulse current strength, the geometrical characteristic of the clad changed markedly. The application of the EMCF led to an increase in clad depth and a decrease in clad height, which led to an increase in dilution rate. The geometrical characteristic did not change significantly when the EMCF was small. The application of the EMCF can inhibit the growth of dendrites crystals, facilitates fine grain formation and improves the uniformity of microstructure. The microhardness improved and the range of microhardness decreased significantly under the condition of the EMCF.
Keywords: Fibre laser, Inconel 625, HT300 grey cast iron, laser-directed energy deposition (LDED), electromagnetic compound field (EMCF)