Articles

Heat treatment of 3D printed metal components has a big impact

2020-10-13

3D printed metal components are almost always heat treated. The treatments remove the internal stresses created in part during printing and change the part's microstructure as needed. Commonly in industrial use, the microstructure's modification targets specific properties like hardness, strength, toughness, and wear resistance.

Opportunities to improve

Stress relief annealing is suitable and done for all parts. The pieces go into the oven mainly before sawing. In this case, they are still attached to the printing plate. Improved properties are sought by altering the microstructure by, among other things, solution and aging. Both treatments improve the strength of the part. The solution treatment homogenizes the material and improves its phase structure. In addition to strength, as a function of the temperature and time typical of each material, aging increases the hardness until the overaging starts. Then the properties of the part start to change in a softer direction.

3D printed components' heat treatment aims for the same properties and values​ specified in the standards for traditionally manufactured metal products. The properties are achieved by the heat treatment cycles. The definition of processes is similarly based on existing, traditionally manufactured part standards.

At Delva, we see that heat treatment standards like AMS 5662 work for 3D printed components, but could be significantly optimized. Namely, the treatments specified for traditional materials and material strengths can be very long in duration. 3D printing is a different kind of manufacturing process, and the metal used already differs from the conventional structure. Besides, the material thicknesses used are typically much lighter in 3D printed components than traditional.

EOS IN939

Some time ago, EOS launched the EOS IN939 material. This extreme temperature heat-resistant nickel alloy traditionally acquires its good material properties in a 50-hour heat treatment cycle, as determined with the standard. Thanks to EOS's optimization work, the 14-hour heat treatment of the parts - less than a third of the standard processing - achieves even better material properties. This development work directly leads to cost and time savings, and as said a better product.

Development requires a lot of resources

The development of heat treatment is essential. In the example of IN939, changing the heat treatment from the standard to the shortened process time and achieved better properties for the parts. There are other similar examples. Development work requires dedication and significant resources. It is essential to realize that risks exist and that properties can also significantly deteriorate from the intended ones due to erroneous heat treatment decisions. In addition to cooperation, patience is, therefore, an asset.

At Delva, we experiment, discuss, and develop with our network of expertise. Our goal is further to increase the benefits of 3D printing for our customers. Delva is delighted with the development work done by EOS Finland in Turku and the support received by users of Eos metal printers. We can see EOS's tireless work to optimize heat treatments reflecting in Delva's everyday life as the best possible instructions and as optimized properties and processes in our customers' components.

Manufacturing process based on target setting

We repeatedly communicate the importance of thoughtful material choice. In our view, the 3D printing materials should be selected on the basis of the function and purpose of the component. Thus, the materials may differ from those used in conventional manufacturing. Also, the heat treatments they require can be unusual and turn out to be quite expensive to commission. Delva strives to use mainly its own furnace for heat treatment, as it is familiar and cost-effective in use. In addition, significant flexibility is gained in the work phase. Doing it yourself develops skills, clarifies responsibilities for part properties, and, as mentioned above, saves a lot of time and often money.

It is worthwhile to invest in more efficient heat treatment of your 3D printed components. Who wouldn't want to produce better products faster and more cost-effectively? The customer need is guiding for us, also in heat treatment. Contact us, and we will discuss solutions according to your needs.

Further information: info@delva.fi and markku.lindqvist@delva.fi.

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