3D Metal Printing Materials

The main chemical components of the raw materials include metal elements and impurity components. The main metal elements commonly used are Fe, Ti, Ni, Al, Cu, Co, Cr, and precious metals such as Ag and Au. The impurity components include Si, Mn, C, S, P, O, etc. in the reduced iron, other impurities mixed from raw materials and powder production, and water and other gases adsorbed on the surface of the powder.

During the molding process, impurities may react with the matrix, changing the properties of the matrix and negatively affecting the quality of the part. The presence of inclusions will also cause uneven melting of the powder, which is likely to cause internal defects in the product. When the oxygen content of the powder is high, the metal powder is not only easy to be oxidized to form an oxide film, but also leads to spheroidization, which affects the density and quality of the parts.

Therefore, it is necessary to strictly control the impurities and inclusions of the raw material powder to ensure the quality of the product. Therefore, the metal powder for metal AM needs to use the metal powder raw material with higher purity.

shape requirements: Common particle shapes are spherical, nearly spherical, flakes, needles and other irregular shapes. Irregular particles have a larger surface area, which is beneficial to increase the sintering drive. However, powder particles with high sphericity have good fluidity and uniform powder feeding and powder distribution, which is beneficial to improve the density and uniformity of the parts. Therefore, powder particles for 3D printing are generally required to be spherical or nearly spherical.

Powder particle size and particle size distribution:Powder particle size and particle size distribution. Studies have shown that the powder is melted and sintered by directly absorbing the energy of the laser or electron beam scanning. In addition, the powder particle size is small, the gap between particles is small, the bulk density is high, and the compactness of the parts after forming is high, so it is beneficial to improve the strength and surface quality of the product. However, if the particle size of the powder is too small, the powder is prone to adhesion and agglomeration, which leads to a decrease in the fluidity of the powder, which affects the transportation of the powder and the uniformity of the powder distribution.

Density:The bulk density is the density of the powder when it is naturally stacked, and the tapped density is the density after vibration. The powder with good sphericity and wide particle size distribution has high bulk density and low porosity, and the formed parts have high density and good forming quality.

Liquidity: The fluidity of the powder directly affects the uniformity of powder spreading or the stability of powder feeding. The powder fluidity is too poor, which is easy to cause uneven thickness of the powder layer and uneven metal melting in the scanning area, resulting in uneven internal structure of the part and affecting the forming quality; while the powder with high fluidity is easy to fluidize, deposit uniformly, and the powder The utilization rate is high, which is conducive to improving the dimensional accuracy and uniform densification of the surface of the 3D printed parts.

Recycling: After the 3D printing process, the unmelted powder left in the powder bed can still be used by sieving and recycling. However, in the high temperature environment for a long time, the powder in the powder bed will have certain performance changes. The recovery rate needs to be selected with the specific process.