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

Laser powder-bed fusion additive manufacturing: Physics of complex melt flow and formation mechanisms of pores, spatter, and denudation zones

Selective Laser Melting (SLM) is a particular rapid prototyping, 3D printing, or Additive Manufacturing (AM) technique designed to use high power-density laser to melt and fuse metallic powders. A component is built by selectively melting and fusing powders within and between layers. The SLM technique is also commonly known as direct selective laser sintering, LaserCusing, and direct metal laser sintering, and this technique has been proven to produce near net-shape parts up to 99.9% relative density. This enables the process to build near full density functional parts and has viable economic benefits. Recent developments of fibre optics and high-power laser have also enabled SLM to process different metallic materials, such as copper, aluminium, and tungsten. Similarly, this has also opened up research opportunities in SLM of ceramic and composite materials. The review presents the SLM process and some of the common physical phenomena associated with this AM technology. It then focuses on the following a...

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Review of selective laser melting : materials and applications

Fine-structured aluminium products with controllable texture by selective laser melting of pre-alloyed AlSi10Mg powder

Mechanical Properties of AlSi10Mg Produced by Selective Laser Melting

https://cyberleninka.org/article/n/443668.pdf

Microstructure and mechanical properties of Selective Laser Melted 18Ni-300 steel

This paper discusses the principle and the relevance of an in situ monitoring system for selective laser melting (SLM). This system enables the operator to monitor the quality of the SLM job on-line and estimate the quality of the part accordingly. The monitoring system consists of two major developments in hardware and software. The first development, essential for a suitable monitoring system, is the design of a complete optical sensor set-up. This set-up is equipped with two commercially available optical sensors connected to a field-programmable gate array (FPGA) which communicates directly with the machine control unit. While the sensors ensure a high-quality measurement of the melt pool, the FPGA’s main task is to transfer the images from the sensors into relevant values at high sample rates (above 10 kHz). The second development is the data analysis system to translate and visualize measured sensor values in the format of interpretable process quality images. The visualization is mainly done by a “mapping algorithm,” which transfers the measurements from a time-domain into a position-domain representation. Further off-line experiments illustrate an excellent compatibility between the in situ monitoring and the actual quality of the products. The resulting images coming out of this model illustrate melt pool variations which can be linked to pores that are present in the parts.

In-situ Quality Control of the Selective Laser Melting Process using a High Speed, Real-Time Melt Pool Monitoring System

Owing to their attractive combination of mechanical properties, high heat conductivity and low weight, the Al–Si alloys found a large number of applications in the Additive Manufacturing field for automotive, aerospace and domestic industries. However, due to their high reflectivity and heat conductivity, they are harder to process by Selective Laser Melting. This work elaborates on both the optimisation of process parameters, in order to get nearly fully dense parts, and the material properties resulting from this specific material process combination. A process parameter window is defined, in which the formed melt pool is stable and meets the set requirements. In this process window, the parameter set for optimal density is defined. It is shown that AlSi10Mg parts produced by SLM have mechanical properties higher or at least comparable to the cast material because of the very fine microstructure.

Karolien Kempen

Papers

Fine-structured aluminium products with controllable texture by selective laser melting of pre-alloyed AlSi10Mg powder

Mechanical Properties of AlSi10Mg Produced by Selective Laser Melting

Microstructure and mechanical properties of Selective Laser Melted 18Ni-300 steel

In-situ Quality Control of the Selective Laser Melting Process using a High Speed, Real-Time Melt Pool Monitoring System

Processing AlSi10Mg by selective laser melting: parameter optimisation and material characterisation