Additive manufacturing of metallic components – Process, structure and properties

Additive manufacturing of metals

Additive manufacturing (AM), widely known as 3D printing, is a method of manufacturing that forms parts from powder, wire or sheets in a process that proceeds layer by layer. Many techniques (using many different names) have been developed to accomplish this via melting or solid-state joining. In this review, these techniques for producing metal parts are explored, with a focus on the science of metal AM: processing defects, heat transfer, solidification, solid-state precipitation, mechanical properties and post-processing metallurgy. The various metal AM techniques are compared, with analysis of the strengths and limitations of each. Only a few alloys have been developed for commercial production, but recent efforts are presented as a path for the ongoing development of new materials for AM processes.

The metallurgy and processing science of metal additive manufacturing

https://dr.ntu.edu.sg/bitstream/10356/88603/1/Anisotropy%20and%20heterogeneity%20of%20microstructure%20and%20mechanical%20properties%20in%20metal%20additive%20manufacturing-%20A%20critical%20review.pdf

Anisotropy and heterogeneity of microstructure and mechanical properties in metal additive manufacturing: A critical review

3D printing of Aluminium alloys: Additive Manufacturing of Aluminium alloys using selective laser melting

Strong morphological and crystallographic texture and resulting yield strength anisotropy in selective laser melted tantalum

Changing the alloy composition of Al7075 for better processability by selective laser melting

Selective Laser Melting (SLM) shows a big potential within additive manufacturing of metals. The competitive mechanical properties compared to conventional processes as well as the geometry freedom are the main advantages of SLM. 316L stainless steel has been investigated in previous works regarding microstructure and mechanical properties. However, the influence of heat treatments has not been fully reported yet. This work studies the influence of different heat treatments applied to 316L stainless steel produced by SLM. The microstructure evolution was investigated for different conditions. Tensile, Charpy and hardness tests were performed on the as built and heat treated samples.

Effect of Heat Treatment of 316L Stainless Steel Produced by Selective Laser Melting (SLM)

Selective Laser Melting (SLM) shows a big potential among metal additive manufacturing (AM) technologies. However, the large thermal gradients and the local melting and solidification processes of SLM result in the presence of a significant amount of residual stresses in the as built parts. These internal stresses will not only affect mechanical properties, but also increase the risk of Stress Corrosion Cracking (SCC). A twister used in an air extraction pump of a condenser to create a swirl in the water, was chosen as a candidate component to be produced by SLM in 316 L stainless steel. Since the main expected damage mechanism of this component in service is corrosion, corrosion tests were carried out on an as-built twister as well as on heat treated components. It was shown that a low temperature heat treatment at 450℃ had only a limited effect on the residual stress reduction and concomitant corrosion properties, while the internal stresses were significantly reduced when a high temperature heat treatment at 950℃ was applied. Furthermore, a specific stress corrosion sensitivity test proved to be a useful tool to evaluate the internal stress distribution in a specific component.

/pdf/corrosion-testing-of-a-heat-treated-316-l-functional-part-2ixd9op4ia.pdf

Maria Montero Sistiaga

Papers

Strong morphological and crystallographic texture and resulting yield strength anisotropy in selective laser melted tantalum

Changing the alloy composition of Al7075 for better processability by selective laser melting

Effect of Heat Treatment of 316L Stainless Steel Produced by Selective Laser Melting (SLM)

Corrosion Testing of a Heat Treated 316 L Functional Part Produced by Selective Laser Melting

New opportunities for using tantalum for implants with Additive Manufacturing