Microstructure and thermal properties of unalloyed tungsten deposited by Wire + Arc Additive Manufacture

Abstract

Tungsten is considered as one of the most promising materials for nuclear fusion reactor chamber applications. Wire + Arc Additive Manufacturing has already demonstrated the ability to deposit defect-free large-scale tungsten structures, with considerable deposition rates. In this study, the microstructure of the asdeposited and heat-treated material has been characterised; it featured mainly large elongated grains for both conditions. The heat treatment at 1273 K for 6 hours had a negligible effect on microstructure and on thermal diffusivity. Furthermore, the linear coefficient of thermal expansion was in the range of 4.5x10 -6 µm m -1 K -1 to 6.8x10 -6 µm m -1 K -1 ; the density of the deposit was as high as 99.4% of the theoretical tungsten density; the thermal diffusivity and the thermal conductivity were measured and calculated, respectively, and seen to decrease considerably in the temperature range between 300 K to 1300 K, for both testing conditions. These results showed that Wire + Arc Additive Manufacturing can be considered as a suitable technology for the production of tungsten components for the nuclear sector.

Gradient of Residual Stress and Lattice Parameter in Mechanically Polished Tungsten Measured Using Classical X-rays and Synchrotron Radiation

“…[3] Relatively high strength and stiffness at high temperatures, together with an excellent corrosion resistance as well as a relatively low price, makes tungsten one of the most commonly utilized hard metals, for example in the military, aerospace, nuclear, electronic and chemical industries. [4] Tungsten can be used to produce structures working at a high temperature, radiation shields, and parts of a nuclear fusion reactor, [5][6][7][8][9][10] multipinhole collimators for magnetic resonance devices, [11] electrical switching contacts, magnetrons for microwave ovens, laser printers, air cleaners, and chemical reactors, etc. [12] Surface finishing, such as polishing, is required for many engineering applications.…”

Wire Arc Additive Manufacturing: A Comprehensive Review and Research Directions

“…The researchers are successfully using arc-based welding technologies in WAAM. The welding processes used in WAAM are gas tungsten arc welding (GTAW), gas metal arc welding (GMAW), and plasma arc welding (PAW) (Ref 48,49). The selection of welding process for WAAM depends the type of material and applications.…”

Microstructural characterization and mechanical integrity of stainless steel 316L clad layers deposited via wire arc additive manufacturing for nuclear applications

“…Wire arc additive manufacturing is performed with one of the arc‐based welding techniques: Gas tungsten arc welding, gas metal arc welding, or plasma arc welding. It can be employed to repair or improve the features on existing components which were made from forging or casting and to manufacture medium‐large structures for power generation, naval, aerospace and several engineering applications [7–11]. Wire arc additive manufacturing technique has successfully manufactured medium‐large size parts using stainless steels, aluminium, titanium and nickel‐based superalloys [12–15].…”