Cobalt-chromium (or cobalt-chrome) is a metal alloy that has gained prominence in a variety of industrial applications, particularly in additive manufacturing. With its unique combination of strength and durability, cobalt-chrome is ideal for creating parts that require high precision and strength under demanding conditions, such as medical and dental components. This alloy stands out not only for its mechanical properties but also for its ability to be molded into complex shapes using 3D printing, opening up new possibilities in the design and manufacture of customized parts. In this guide, we’ll explore the properties of cobalt chromium, its advantages in 3D printing, and the main applications and manufacturers of this material on the market.
Characteristics of the Material
As its name suggests, this metal alloy (CoCr) consists mainly of the chemical elements chromium and cobalt. It also contains a small proportion of other chemical elements, such as molybdenum, tungsten and nickel. It is a non-magnetic alloy obtained by advanced metallurgical processes involving the fusion of cobalt and chromium with other elements to enhance its mechanical properties and strength. One of the most common methods of obtaining them is electric furnace melting, in which these metals are melted at high temperatures in induction or electric arc furnaces. In some cases, once the liquid alloy has been obtained, it can be subjected to a forging process, which involves heating and molding the material by applying pressure.
This material is characterized by its strength and durability
However, when required in the form of metal powder for 3D printing applications, cobalt-chrome can also be obtained by sputtering. In this process, the alloy is converted into fine particles using atomization or sputtering techniques, enabling it to be used in additive manufacturing technologies based on powder beds. These techniques make it possible to create complex parts from metal powder, offering greater flexibility in the design and manufacture of high-precision components. Among cobalt-chrome’s most outstanding characteristics are:
- Corrosion resistance, especially in hostile environments such as those with high chloride concentrations. This is particularly important in medical applications, where contact with body fluids is constant.
- High hardness and mechanical strength make this alloy an ideal choice for parts subject to heavy mechanical loads. In addition, its ability to maintain structural integrity even at elevated temperatures is a significant advantage.
- Biocompatibility: thanks to its corrosion resistance and chemical stability, cobalt-chromium alloy is highly biocompatible. As a result, it generally does not cause undesirable reactions in the human body, enabling it to be used in the medical sector.
- High thermal conductivity enables it to dissipate heat efficiently in certain applications.
- High thermal stability, i.e., resistance to deformation at elevated temperatures. It is therefore ideal for components operating in extremely hot conditions.
3D Printing Cobalt Chrome
Cobalt-chromium alloy can be used in additive manufacturing, in powder form, to create parts with complex geometries. The material is mainly compatible with processes such as laser powder bed fusion (LPBF), electron beam melting (EBM) or selective laser melting (SLM). The melting point of the cobalt-chrome alloy is around 1,200-1,400°C, depending on the exact composition of the alloy. This is quite a high melting point compared to other metals commonly used in 3D printing, such as aluminum or stainless steel. For this reason, the cobalt chrome 3D printing process must be carried out at high temperatures, requiring precise control of the printing environment and high-quality equipment.
The cobalt-chromium alloy is compatible with powder bed technologies (photo credits: Eplus3D).
The use of a cobalt-chrome in 3D printing presents some specific technical considerations due to its physical and chemical properties. As the alloy has a high melting temperature, laser energy must be adjusted to avoid evaporation or poor fusion of the material. Furthermore, as the alloy contains chromium, a highly reactive metal, additional precautions must be taken to control the printing environment. The use of inert argon or nitrogen atmospheres is recommended to avoid undesirable reactions with oxygen. Another important aspect is powder fluidity. Cobalt-chrome is less fluid than other metals, which can make it difficult to distribute the powder evenly during the manufacturing process. To remedy this, finely-tuned printing parameters are required to ensure even melting and good surface quality of the parts produced.
After 3D printing, several post-processing steps need to be carried out. Firstly, the parts must be cooled slowly to avoid internal stresses or deformations. Next, the parts are cleaned, which includes de-powdering and removal of print media (if applicable). In some cases, particularly in medical applications, it may be necessary to apply a heat treatment, such as annealing. This treatment improves the crystalline structure and mechanical strength of the alloy, and hence of the parts. Finally, techniques such as polishing (electrolytic or mechanical) are commonly used to obtain a smooth, high-quality surface.
Main Applications and Manufacturers on the Market
Thanks to its corrosion resistance, hardness and biocompatibility, cobalt-chrome 3D printing is used in a multitude of industries. It is mainly used in the manufacture of medical components, such as orthopedic implants, dental prostheses and surgical devices. In these applications, parts must have high mechanical strength and be perfectly compatible with the human body. It is also used in the aerospace and automotive industries for the production of parts subject to extreme temperature and wear conditions, such as turbines and engine components.
Cobalt chromium is widely used in medical and dental applications.
Several companies offer not only additive manufacturing solutions, but also materials compatible with their machines. Colibrium Additive (part of GE Aerospace) is a leading manufacturer of metals for 3D printing. In particular, it develops its own CoCr alloys compatible with its LPBF and EBM machines. EOS, Eplus3D, Renishaw and 3D Systems, among others, also offer cobalt chromium powders designed and tested for use in these companies’ metal systems.
It’s also worth noting that a number of material suppliers offer this metal for the additive manufacturing sector. These include Carpenter Additive, with its PowderRange® (CCM®-MC and CCM®), and Sandvik with the standard Osprey® range of metal powders, which includes cobalt chromium powder for additive manufacturing.
What do you think of using cobalt-chrome for 3D printing? Let us know in a comment below or on our LinkedIn or Facebook pages! Plus, don’t forget to sign up for our free weekly Newsletter to get the latest 3D printing news straight to your inbox. You can also find all our videos on our YouTube channel.
*Cover Photo Credits: PiTch_ / David Doleac