Monitoring melt pool asymmetry in gas metal arc-directed energy deposition

Cross-sectional asymmetry of melt pools along adjacent tracks results in an uneven build surface in gas metal arc-directed energy deposition. We present here a novel attempt on real-time monitoring of melt pool cross-sectional asymmetry in terms of its lateral and angular deviations from the track centreline using a two-colour quotient thermal camera. The melt pool lateral and angular deviations are found to be 2–3 mm, and 8–12°, respectively, for the range of process conditions. A unique analytical methodology is proposed that shows a hatch spacing of around 72–76% of the width of a deposited track can reduce melt pool asymmetry and layer height variations along adjacent tracks, which is also observed experimentally.</p

An investigation on friction hydro-pillar processing

<p>Friction hydro pillar processing (FHPP) is a novel technique to fill in crack-holes in thick-walled metal structures by an external stud and forming a solid-state bond between the stud and the metal substrate. During the process, the stud is rotated against the crack-wall to facilitate friction heating and flow of plasticized material for proper filling of the crack-hole. We present here a coupled experimental and numerical study on FHPP of ASTM A36 steel to understand the effect of processing conditions on the joint structure and properties. An axi-symmetric heat transfer analysis is carried out to compute the temperature field. The computed thermal cycles are used to estimate the hardness distribution across the joint. The estimated thermal cycles and hardness distribution are tested with the corresponding experimentally measured results.</p