Tungsten is a compact and strong metal. Because of its excellent corrosion resistance, it has been widely used in many fields such as chemical industry. However, its high hardness and high melting point have hindered its development in the field of 3D printing. Now, a research team has challenged this problem and published a paper entitled "Effects of Processing Parameters in Laser Powder Bed Fusion Process on Densification, Microstructure and Crystal Structure of Pure Tungsten".
The researchers explained: "We applied the laser powder bed manufacturing process to refractory metals, such as the pure tungsten powder in the paper. A process solution for manufacturing high-density parts was proposed, and the effect of laser energy density was studied. "Scientists have evaluated the quality of the process using optical microscopy, XCT, SEM, and EBSD, and the results show that laser energy density can process tungsten materials into good functional parts."
Depending on the process conditions, the bulk density and optical density of tungsten range from 94% to 98%, but due to the presence of micro and macro residual stresses, the part still shows defects such as microcracks.
The researchers continued: "The results of the analysis of the microstructure and crystal structure show that the melting grooves formed under the laser beam are ideally oriented and solidified by the epitaxial growth mechanism. The texture analysis results of EBSD show that tungsten has // Z Orientation parallel to the direction of construction. "
Both types of tungsten samples are produced by 3D printing and analyzed using a scanning electron microscope. Although these parts still have the problem of being easily cracked, researchers have determined that as long as the density and quality of 3D printed samples are improved, they will definitely make a difference in the fields of medical radiation protection and nuclear imaging and other plasma environments. They also concluded that laser powder bed fusion technology can be used to make relatively dense tungsten parts.
The researchers also added: "The results of micro, macro, and local texture analysis show the columnar grain structure produced by the epitaxial growth mechanism, which is consistent with the performance of other pure metals. Laser energy with a density of up to 348 J / mm3 can Make the sample show a strong // Z fiber structure. It is speculated that this may be related to the shape of the melting tank, the high thermal conductivity of tungsten, the low surface tension, and the 67 ° grating direction rotation of the deposited layer in Renishaw AM This has led to this phenomenon. "
3D printing can provide new application opportunities for tungsten materials, producing parts with high accuracy and complexity. Other researchers have studied the 3D printing process of tungsten materials, and some of them have even been commercialized. Despite the challenges, tungsten has proven to be a valuable 3D printing material, and many experts are interested in its heat resistance.