Feasibility Study on Composite Manufacturing of Laser Powder Bed Melting and Cold Casting

It is reported that researchers from the Technical University of Munich in Germany have reported a feasibility study on the composite manufacturing of EN AC-42000 alloy by combining laser powder bed melting and cold casting. The related research titled "Feasibility study on hybrid manufacturing combining laser based powder bed fusion and chill casting on the example of EN AC-42000 alloy" was published in Materials Science and Engineering Technology.

Laser based powder bed melting can be combined with casting to form a composite manufacturing process. This is to simultaneously utilize the advantages of both processes. In order to investigate the challenges associated with the use of aluminum alloys, researchers first conducted experiments using two common independent processes, the alloy EN AC-42000. Place the EN AC-42000 alloy samples that have undergone different surface treatments into a sand mold, and then cast them onto the aluminum melt. The contact area between the partially melted insert and the casting material was examined using an optical microscope. The results indicate that the main challenges include binding issues caused by the presence of oxides and high porosity. The high porosity can be traced back to the increase in porosity of inserts during laser powder bed melting.

Figure 1: Composite casting aims to combine the advantages of laser powder melting and die casting.

Figure 2: a) Experimental method scheme. The cylindrical aluminum sample is completely cast in. b) The image of inserting the sample into the four tubes inside the sand mold for the casting process.

Figure 3: Overview of samples after cutting, grinding, and polishing.

Figure 4: Microscopic image of the sample: Visible contact surfaces and pores are depicted in areas 1 and 2. The enlarged area 2 attempts to capture evidence of metal fusion or non fusion.

The purpose of this study is to gain a preliminary understanding of the challenges faced in combining laser powder bed melt additive manufacturing with casting. The results indicate that the porosity of EN AC-42000 alloy significantly increases. The increase in porosity is a major issue in the feasibility of the process, and further research should be conducted on possible solutions to prevent a significant increase in porosity.

In addition to porosity, there is also a certain degree of material fusion between castings and inserts manufactured by laser powder bed melting. In terms of process feasibility, these results mean that the oxide layer needs to be thoroughly removed and prevented from re growing after removal. In further research, methods for removing the oxide layer and stabilizing this deoxygenation state should be explored to make them suitable for components manufactured by laser powder bed melting.

Paper link: https://doi.org/10.1002/mawe.202300403

Source: Yangtze River Delta Laser Alliance