Part Tailoring in Metal-Additive Manufacturing: A Step towards Functionally Graded Customized Stainless-Steel Components Using Laser Powder Bed Fusion

Abstract

The aim of this project is to demonstrate a proof of concept by using Additive Manufacturing (AM) technology in order to demonstrate its viability for the production of tailor-made components with regions of varying (higher and lower) hardness and surface roughness within a single part. In order to do this, first a test piece is designed and printed following a full factorial design of the experiment with eight runs with varying process parameters set within different regions of one part. The structure is printed several times with the laser-powder-bed-fusion-based metal-additive-manufacturing system “Sodick LPM 325” using AISI 420 in order to test and validate the change in the achievable mechanical property and surface roughness. The above-mentioned quality marks are characterized using a tactile profilometer, Rockwell test and part density, and the results are statistically analyzed using MATLAB. The results show that the linear energy density plays a significant role in controlling the surface roughness of the top surface of the components while the hardness on the top surface is unaffected. On the side surfaces, it is known that the layer thickness plays a significant role on the surface roughness as well as hardness. Looking at the results obtained, it is seen that the variation in the obtained side surface roughness is not significant to changes in the Linear Energy Density (LED) as the layer thickness was kept constant, with only slight reductions in hardness seen. The annealing process resulted in a significant reduction in hardness. This work has shown that through the careful tailoring of processing conditions, multi-functionality within one part can be integrated and has created promising avenues for further research into achieving fully functionally graded structures.

Keywords

• laser powder bed fusion
• AISI 420
• functional grading
• tailored mechanical properties
• hardness
• surface roughness