How Is Heat Treatment Used in Metal 3D Printing?

Heat treatment plays a crucial role in 3D printing metal parts and prototypes. It is offered as a post-processing service for a range of materials used in Direct Metal Laser Sintering (DMLS).

While heat treatment is not always necessary, it can markedly improve the mechanical properties of 3D printed components. Heat treating metal parts therefore has many potential applications in a range of industries, from healthcare to aerospace.

In this guide, we will discuss how heat treatment works, and how it can alter the properties of 3D printed metal.

What Is Heat Treatment in Metal 3D Printing?

Heat treatment is a controlled process that involves heating and cooling metal to change its microstructure. This can significantly improve an object’s strength, hardness, ductility and other important qualities. It does not alter the external structure or dimensions of the object – it only affects its internal structure.

In metal 3D printing, post-processing services such as heat treatment are used to enhance both performance and durability. Techniques may vary depending on the type of metal, the desired properties and its intended application. Various metals, including steel, aluminium and titanium alloys, can be heat treated to improve their performance.

What Are the Benefits of Heat Treatment in Metal 3D Printing?

There are many advantages of investing in the heat treatment of 3D printed metal parts. For example:

• Enhanced mechanical properties. Heat treated components benefit from better performance, durability, and resistance to wear and tear.
• Reduced residual stress. Residual stresses can cause issues such as cracking, ‘creeping’ (permanent deformation) and part failure. Heat treatment effectively reduces these stresses, ensuring that 3D printed metal components retain their intended form and function.
• Increased corrosion resistance. Certain heat treatment processes can increase the corrosion resistance of metal 3D printed components, improving their longevity in harsh environments.
• Decontamination. Thermal treatment can also remove contaminants and imperfections on the metal’s surface, such as oxide films.

Overall, heat-treated 3D printed metal parts are significantly better able to meet the rigorous demands of many applications. They may be used in a wide range of industries, including aerospace, nuclear energy, automotive, medical and construction. For example, 3D-printed jet engine blades may be heat treated to withstand extreme conditions, or in producing medical breakthroughs.

How Does the Heat Treatment Process Work?

Heat treatment in 3D metal printing involves a series of carefully measured steps, usually with the use of a gas-controlled furnace. It takes place after the part has been created, as part of the post-processing phase. Thermal treatments may be carried out alongside other services such as post-machining, tapping and reaming and surface finishing.

The act of heat treating 3D printed parts typically takes place in three stages: heating, heat preservation and cooling. However, the specific process may vary depending on the type of thermal treatment used. Different heat treatments may be chosen depending on the metal 3D printing material and the desired outcome.

Quenching

Quenching is a two-step thermal treatment that involves heating a metal part to its critical temperature, followed by rapid cooling in a liquid such as water or oil. This process can help to improve hardness, weather resistance and corrosion resistance. It can be used for a range of alloys including steel, aluminium and titanium.

Tempering

Tempering is a heat treatment technique that is usually employed after quenching. The process involves heating the metal part to a temperature below its critical point (or melting point) and then cooling it down in air or water. Depending on the temperature, tempering can be used to alter a material’s hardness, ductility, strength and toughness.

Annealing

Annealing is a heat treatment process commonly used for steel. The part is heated to a specific temperature that allows for recrystallisation, repairing any defects within the internal structure. It is then held at that temperature, and then cooled slowly at a precisely controlled rate. Solution annealing helps to reduce internal stresses, increase toughness, ductility and machinability and improve magnetic properties.

Normalising

Normalising is a heat treatment process that involves heating the part to a specific temperature above its critical point and then cooling it in the air. It is cooled at a rate which is faster than annealing, but slower than quenching. This process is designed to improve toughness, reduce hardness, improve plasticity and reduce the risk of cracking.

Why Choose LPE’s Custom Metal 3D Printing Service?

If you are looking to 3D print metal components or prototypes, LPE can help. We offer a fast, accurate and reliable custom DMLS metal 3D printing service with a turnaround time of 5-10 days. Choose between standard and high-resolution DMLS, and select from a range of high-quality materials including stainless steel, titanium, aluminium and Inconel.

We also provide a wide range of specialist in-house post-processing services for metal 3D printed parts. This includes heat treating, post-machining, advanced surface finishing and more.

To learn more about our custom metal 3D printing process and discuss your requirements, contact LPE today. Alternatively, click here to request a quote for your next project.