Development of microstructure, mechanical properties and residual stress in the interface region of laser metal deposited IN718

Project aim

To develop fundamental knowledge on the interface region between substrate and laser deposited Inconel 718. Constructing an experimentally validated thermomechanical model which simulates the temperature history of an as-deposited part, this thermodynamic information will aid the understanding of the material's response via microstructure, mechanical properties, and residual stress.

Project background

During laser metal deposition (LMD) the material experiences a fluctuation of sharp thermal gradients, rapid cooling, and remelting temperatures. Inconel 718, a precipitation-hardenable nickel-based superalloy is a very versatile and temperature sensitive material used to operate under extreme conditions. By developing parts via subsequent layer build-up, the material experiences a collaboration of thermal gyrations, temperature gradients, and solidification/cooling rates. Encapsulating the thermal history of an as-deposited IN718 component becomes advantageous when optimising the microstructure.

A thermomechanical model will simulate the temperature history and mechanical stresses during deposition, which will be experimentally validated. By fluctuating the process parameters i.e. laser power, scan speed, etc. the material's microstructure can be deduced and therefore optimised for enhancing mechanical properties. With the sharp alterations in temperature comes the accumulation of residual stresses, which will be linked to microstructure and properties.