DED Metal 3D Printing Study Reduces Errors in Functionally Graded Materials – 3DPrint.com

One of these kinks is the lack of process control generally and errors in components. The Korean team has now looked into controlling the mixture of different materials at different ratios to see where errors occur. What’s really cool is that they did this for directed energy deposition (DED) which has seen a lot less attention than powder bed fusion (PBF) in research circles. In this case, they looked at the interface layers between different materials, 316 (L) stainless steel and Inconel 718. Between layers, cracks and defects can appear and, ideally, the right mix of materials relative to one another can reduce this.

The team used an Optomec LENS system for its experiment, building a series of parts and playing with the gradients, as well as laser power and feed rate. They created components whereby the steel was printed on the Inconel, with graded variants mixed in at 10% and 25%. In the sample without a gradient, cracks formed between the two materials. In contrast, the graded samples “had cracks only in specific regions due to ‘columnar-to-equitaxial transition’ (a transition in the microstructure of the FGM), precipitation, or the inclusion of titanium, aluminium or chromium impurities.” Meanwhile, the 25% graded sample “showed the highest tensile strength and elongation.”

“These findings will lead to improvements in the field, such as reduced costs, extended component lifespans in equipment, and enhanced functionality,” Professor Shim opined.