1 Strength and toughness of high temperature
In the aerospace industry, material performance is much evaluated on the strength and toughness under high temperature situations. For metal 3D printing, high temperature materials must be able to sustain enough strength and toughness even at very high temperatures-that of over 1000 ° C. Apart from the high melting point of the substance itself, this calls for a stable crystal structure and microstructure at high temperatures to prevent failure brought on by thermal deformation or thermal fatigue.
For instance, the aerospace sector has extensively utilised nickel based high-temperature alloys including In625 and In718 because of their outstanding high-temperature strength and toughness. Using metal 3D printing technology, these alloys can be manufactured components with intricate geometries, like engine turbine blades and combustion chambers, which run at tremendous temperatures and demand materials with great high-temperature performance.
2 Resistance to Oxidation and Corrosion
The reaction between materials and oxygen will speed under high temperatures, causing oxidation and corrosion. To thus lengthen the service life of the components, high-temperature materials for metal 3D printing must possess great oxidation and corrosion resistance. The material must develop a stable oxide film at high temperatures to prevent oxygen from further corroding the substrate material and so improve the antioxidant performance. Materials with corrosion resistance must keep good performance in demanding conditions including high temperature, great pressure, and corrosive fluids.
Using metal 3D printing technology allows the often used materials in the aerospace sector-such as titanium alloys and stainless steel-to be optimised for their microstructure and enhanced for oxidation and corrosion resistance. For instance, titanium alloy's great temperature and corrosion resistance make it rather common in the aircraft sector. More sophisticated and complicated constructions made possible by 3D printing technologies help to increase component corrosion resistance.
3 Thermal expansion coefficient and stability
Good thermal stability is another requirement for high temperature materials for metal 3D printing; that is, the material's performance won't vary much across time at high temperatures. To prevent performance loss brought on by thermal ageing, this calls for the material to have a stable crystal structure and chemical composition at high temperatures. As it directly influences the dimensional stability and assembly accuracy of the components at high temperatures, the thermal expansion coefficient of the material is also a crucial issue in mind.
In this sense, nickel based and iron-based high-temperature alloys are rather successful. In high temperatures, they not only have low coefficient of thermal expansion but also great thermal stability, thereby guaranteeing the dimensional stability and assembly correctness of components in such surroundings. These features make iron-based and nickel based high-temperature alloys the ideal choice for metal 3D printing high-temperature materials in the aerospace sector.
4 Needs for post-processing and material handling
While metal 3D printing technology offers great design freedom, processing performance and post-processing needs of materials still have to be taken into account while processing high-temperature materials. High melting points and poor flowability of high temperature materials demand great standards for printing machinery and process parameters. Thus, superior powder flowability, melting and solidification properties, as well as predictable microstructure evolution, are requirements for metal 3D printing high-temperature materials.
Furthermore rather substantial post-processing needs for high-temperature materials in metal 3D printing are present. Appropriate heat treatment techniques are needed to remove residual stress, maximise microstructure, and increase performance since high-temperature materials are sensitive to thermal deformation and cracking at high temperatures. For components with intricate geometric forms, meantime, surface treatment and precision machining methods also help to satisfy design criteria.
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