Critical deposition height for sustainable restoration via laser additive manufacturing

Abstract

Laser material deposition based restoration of high-value components can be a revolutionary technology in remanufacturing. The deposition process induces residual stresses due to thermomechanical behavior and metallurgical transformations. The presence of tensile residual stresses in the deposited layer will compromise the fatigue life of the restored component. We have developed a novel fully coupled metallurgical, thermal and mechanical (metallo-thermomechanical) model to predict residual stresses and identified a critical deposition height, which ensures compressive residual stresses in the deposited layer. Any lower deposition height will result in tensile residual stresses and higher deposition height will result in excessive dilution (substrate melting). We have validated the model using neutron and micro-focus X-ray diffraction measurements. This study highlights that the critical deposition height corresponds to the minimum cooling rate during solidification. It addresses one of the major outstanding problems of additive manufacturing and paves a way for “science-enabled-technology” solutions for sustainable restoration/remanufacturing.

Residual Stress Simulation of Heterogeneous Cladding Layer Between SiC/Ti6Al4V

“…Due to the phase transformation during laser cladding, in addition to the conventional elastic-plastic deformation, it also produces thermal expansion strain and phase transformation expansion strain. The common non isothermal phase transformation includes diffusion phase transformation and non diffusion phase transformation [9]. This study simulates the phase transformation process of TC4 based on the former.…”

Development and Modeling of a Robotic Restoration System Based on Laser Directed Energy Deposition

“…The 3D fully coupled metallo-thermomechanical model has been developed in order to determine the residual stress introduced due to volume dilation, transformation plasticity, and differential thermal expansion in laser DED process. The Marangoni effect [20] and the ricochet of the powder particles [21] are neglected and the Gaussian profile is taken as powder deposition profile [22]. The modeling has been done using finite element analysis software ABAQUS with user defined subroutines.…”

“…The minimum amount of dilution required for a sound bond between substrate and deposition with the minimum laser power is given by D min . The model has been validated using the experimental techniques, namely neutron diffraction and X-ray diffraction [22] for residual stress and dilution is also experimentally validated by the authors' research group [26]. Further details of the governing equations, boundary conditions and methodology are available in previous publications by the same research group [27].…”

Study on fatigue crack propagation behavior of TA15 titanium alloy repaired by laser deposition repair

“…So, not only should mechanical properties of repaired parts meet the requirements but also the fatigue crack propagation rate (FCPR) need meet the predetermined standard. 12,13 Once the crack rapidly propagates, there are serious consequences to the normal service of aircrafts, which makes it necessary to study the fatigue crack propagation behavior of TA15 by repaired. In addition, the fatigue crack behavior of titanium alloy is closely related to microstructure.…”