Advanced Processing and Machining of Tungsten and Its Alloys

Abstract

Tungsten is a refractory metal with the highest melting temperature and density of all metals in this group. These properties, together with the high thermal conductivity and strength, make tungsten the ideal material for high-temperature structural use in fusion energy and other applications. It is widely agreed that the manufacture of components with complex geometries is crucial for scaling and optimizing power plant designs. However, there are challenges associated with the large-scale processing and manufacturing of parts made from tungsten and its alloys which limit the production of these complex geometries. These challenges stem from the high ductile-to-brittle transition temperature (DBTT), as well as the strength and hardness of these parts. Processing methods, such as powder metallurgy and additive manufacturing, can generate near-net-shaped components. However, subtractive post-processing techniques are required to complement these methods. This paper provides an in-depth exploration and discussion of different processing and manufacturing methods for tungsten and identifies the challenges and gaps associated with each approach. It includes conventional and unconventional machining processes, as well as research on improving the ductility of tungsten using various methods, such as alloying, thermomechanical treatment, and grain structure refinement.

High‐Resolution Patterning of Organic–Inorganic Photoresins for Tungsten and Tungsten Carbide Microstructures

“…Additionally, the resolution of the sintered tungsten parts is limited to hundreds of micrometers. [ 24,29 ]…”

“…[1] Unfortunately, many of their advantageous physical properties, for example their high melting temperature as well as their brittleness, [1] make it notoriously difficult to structure tungsten and tungsten carbide since traditional machining techniques such as forging, casting, cutting, and milling cannot be used. [24][25][26] The conventional method to shape tungsten and tungsten carbide is by powder metallurgy, wherein a high-purity tungsten powder (and potentially a carbon source) is compressed into the desired shape to form the green compact. Subsequently, the sintering step is carried out at 2000-3050 °C (tungsten) and 1350-1600 °C (tungsten carbide) in high-purity dry hydrogen atmosphere.…”

“…Additionally, the resolution of the sintered tungsten parts is limited to hundreds of micrometers. [24,29] Common machining techniques for high-melting and brittle materials such as tungsten and tungsten carbide are noncontact subtractive machining methods. These techniques are generally used for the manufacturing of, for example, micropillars and microgrooves.…”

Effects of pH Values and H2O2 Concentrations on the Chemical Enhanced Shear Dilatancy Polishing of Tungsten

“…Ultra-precision polishing is the final processing method to reduce the surface roughness of workpiece, remove the damaged layer, and obtain high surface accuracy and excellent surface quality [ 9 , 10 , 11 ]. However, as a typical hard and brittle material, there are great challenges in the ultra-precision polishing of tungsten due to the high hardness, high brittleness, and great wear resistance of material [ 12 , 13 ].…”

Performance optimisation of the turning process along with multi-surface heating process

“…Due to its composition (>25% chromium and nickel), duplex SS exhibits higher strength than austenitic SS, such as the 304, 308 and 316 grades of SS. This, however, poses challenges for machining through traditional methods [1][2][3]. Various studies have attempted to resolve this problem.…”