Parametric study of development of Inconel-steel functionally graded materials by laser direct metal deposition

• Functionally graded steel and nickel super-alloy structures have been developed.
• Mechanical properties of FGMs can be controlled by process input parameters.
• SDAS is strongly dependent on the laser power and powder mass flow rate.
• Carbides provide a mechanism to control the hardness and wear resistance of FGM.
• Tensile strength of FGM is dependent on the laser power and powder mass flow rate.

Laser direct metal deposition (LDMD) has developed from a prototyping to a single and multiple metals manufacturing technique. It offers an opportunity to produce graded components, with differing elemental composition, phase and microstructure at different locations. In this work, continuously graded Stainless Steel 316L and Inconel 718 thin wall structures made by direct laser metal deposition process have been explored. The paper considers the effects of process parameters including laser power levels and powder mass flow rates of SS316L and Inconel 718 during the deposition of the Steel–Ni graded structures. Microstructure characterisation and phase identification are performed by optical microscopy and X-ray diffraction techniques. Mechanical testing, using methods such as hardness, wear resistance and tensile testing have been carried out on the structures. XRD results show the presence of the NbC and Fe2Nb phases formed during the deposition. The effect of experimental parameters on the microstructure and physical properties are determined and discussed. Work shows that mechanical properties can be controlled by input parameters and generation of carbides provides an opportunity to selectively control the hardness and wear resistance of the functionally graded material.