Heat treatment of 3D-printed metal components

The project brief is to develop, test and optimise heat treatments to improve the properties of additive-manufactured metal components.

Factsheet

  • Lead department Engineering and information technology
  • Institute Applied Laser, Photonics and Surface Technologies (ALPS)
  • Research unit Additive Manufacturing
  • Duration (planned) 01.01.2018 - 31.12.2019
  • Project management Simon Kleiner
  • Head of project Simon Kleiner
  • Project staff Jürg Dänzer
    Josef Zürcher
  • Keywords Additive Manufacturing, Heat Treatment

Initial situation

Additive manufacturing (AM), colloquially known as 3D printing, results in a different microstructure of metallic components than classic manufacturing processes such as casting or forging. This means that the usual heat-treatment processes developed for castings or forgings may not be ideal for additively manufactured metal parts and therefore need to be adapted.

Selective laser melting (SLM) is one of the most common AM processes for metallic materials, which is why our current project focuses on the heat treatment of SLM-manufactured components.

Goals

The aim of the project is to develop heat-treatment processes that are specifically suited to SLM-manufactured components. This requires a basic understanding of the relationship between alloy composition, manufacturing and treatment processes, microstructure and material properties.

Procedure

The first phase examined the aluminium alloy AlSi10Mg and the steel 17-4 PH. Their chemical composition allows both alloys to be precipitation-hardened. The response behaviour of SLM-manufactured parts to corresponding heat treatments is analysed in comparison with cast or forged materials. By studying the microstructure using light microscopy and electron microscopy (SEM) and determining the mechanical properties, i.e. tensile strength, elongation at break, hardness and toughness, we can understand how these factors relate to each other and derive optimisations for the heat-treatment processes.

Solution

The very fine microstructure of SLM components means that the internal processes during heat treatment take place faster than for classic castings with a coarser microstructure. Solutions therefore tend to involve shorter treatment times and faster cooling speeds.

Since the entire field of AM production technology is evolving very quickly at the moment, the entire process chain must always be considered. New developments in the field of metal powders and their manufacturing methods, as well as new developments and refinements in 3D printing processes, are certain to affect the microstructure of the metal components produced in this way, which is why it will be necessary to make more or less major adjustments in the heat treatment of such parts on a regular basis.