Introduction to common metal 3D printing materials

Maraging steel (Tool steel)

Maraging steel can be quite expensive, mostly due to its high levels of alloying (~0.03% carbon, ~17 to 19% nickel, and ~8 to 12% cobalt) necessary to provide a combination of both high tensile strength and high fracture toughness.

Quality often comes at a price, and although it is rather expensive, maraging steel is a material that offers one of the best strength-to-weight ratios on the market and high damage tolerance. Maraging steel has outstanding mechanical properties and can be heat-treated easily to deliver superior hardness and durability.

This makes the material ideal for a wide range of tooling applications such as injection molding tools, cores, and inserts of die casting, punch pressing, as well as for heavy-duty engineered parts, such as in automotive and aerospace applications.

• Commonly used alloys: MS1, 18Ni1400, 18Ni1700, 18Ni1900, 18Ni2400, 17Ni1600 (cast)
• Material format(s): Powder, filament
• 3D printing technology: Direct Metal Laser Sintering (DMLS), Fused Filament Fabrication (FFF)

Stainless steel

Stainless steel is known to be a less expensive alternative to titanium or nickel, while still having very valuable characteristics.

Due to its superior hardness and toughness, excellent corrosion resistance, good weldability, and highly ductile properties, stainless steel has become popular in the aerospace, oil and gas, food services, and health care industries.

• Commonly used alloys: 17-4PH and 316L alloys
• Material format(s): Powder, filament
• 3D printing technology: Direct Metal Deposition (DMD), Binder Jetting, Direct Metal Laser Sintering (DMLS), and Stratoconception

Titanium

With its superior biocompatibility, great strength and durability, high corrosion resistance, and good density, titanium is an interesting material for harsh environment applications related to the automotive, aviation, and medical/dental sectors.

A perfect example of industrial 3D printed titanium is Bugatti. In 2018, a dedicated brake caliper brake caliper pattern has been optimized with a more organic shape. The 45-hour print succeeded in making the part 40% lighter and capable of enduring up to 125 kg per square millimeter.

• Commonly used alloys: Ti6Al4V or Ti64
• Material format(s): Powder, filament
• 3D Printing technology: Direct Energy Deposition (DED), Electron Beam Melting (EBM), Fused Filament Fabrication (FFF)

Aluminum

Aluminum is a material of choice for the automotive and aerospace industries. It is primarily used to produce lightweight, geometrically complex parts that meet the standards of these demanding industries.

Aluminum has good chemical resistance, great corrosion resistance, and, most importantly, has one of the best strength-to-weight ratios of any metal. Its post-processing convenience, ability to withstand high temperatures, and thermal and electrical conductivity are also very important characteristics for heavy industries.

• Commonly used alloys: AlSi10Mg, AlSi12, AlSi12Mg alloys, Scalmalloy, ALSi7Mg, AlSi7Mg0, Al 6061 and Al 7075, AU4G1
• Material format(s): Powder, filament
• 3D printing technology: Laser powder bed fusion (LPBF), electron beam powder bed fusion, binder jetting, and more rarely fused deposition modeling (FDM)

Cobalt chromium alloy

Although it is sometimes used to produce engine components, the main domain of use of this material is in medical applications such as surgical and dental implants.

Indeed, it is fully biocompatible, has high strength, high resistance to corrosion as well as temperature resistance, and is non-magnetic. This makes it a perfect material for medical usage.

• Commonly used alloys: CoCrMo
• Material format(s): Powder
• 3D printing technology: Direct Metal Laser Sintering (DMLS)

Nickel alloys

Nickel is an incredibly versatile material capable of alloying with many other metals. Ideal for demanding 3D printing applications, nickel alloys find use in a wide range of demanding industries such as aerospace, chemical processing, and shipbuilding.

Due to their high durability at elevated temperatures and extensive corrosion resistance in extreme environments, they can be used, for example, in gas turbine blades for jet engines, turbine power plants, and in highly critical nuclear power systems.

In addition, parts made of nickel alloys have good tensile strength and fracture resistance.

• Commonly used alloys: Inconel 625, Inconel 713, Inconel 718, Inconel 738, Inconel 939, Hastelloy X, Haynes 282, Amperprint alloy 625 and 718
• Material format(s): Powder, filament
• 3D printing technology: Direct Metal Laser Sintering (DMLS), Fused Filament Fabrication (FFF)

Copper-based alloys

3D printing copper with traditional metal powder-based 3D printing technologies, such as direct metal laser sintering (DMLS), has been a long-standing challenge due to copper’s high thermal conductivity.

The most common process for 3D printing copper is powder bed fusion. But new processing methods, such as Markforged Metal X fused filament fabrication (FFF), are helping to improve the use of copper for additive manufacturing.

Thanks to their excellent thermal and electrical conductivity, coupled with good mechanical properties and high malleability, copper-based alloys are ideal for tooling, thermal management applications, and electrical engineering, such as the fabrication of inductors, electrodes, or even heat exchangers.

• Commonly used alloys: CuNi2SiCr, CuCrZr, CuCP, Cu
• Material format(s): Powder, filament
• 3D printing technology: Direct Metal Laser Sintering (DMLS), Fused Filament Fabrication (FFF)

Precious metals

3D printing of precious metals is ideal for industries such as jewelry, watches, dentistry (crowns, inlays, and onlays), and electronics because of the high levels of design freedom it offers.

But direct manufacturing of these precious metals can be challenging. Indeed, most precious metals (gold and silver for example) are highly reflective and thermally conductive. Traditional AM laser-based printers are unable to completely melt the materials and create a homogeneous part. Only a few manufacturers have developed 3D printers performant enough to process these precious metal materials using Direct Metal Laser Sintering (DMLS) or Material Jetting.

It is also important to note that precious metal powders can be very costly. For this reason, most precious metal 3D printing applications involve indirect manufacturing, with a wax model to be used for investment casting.

• Commonly used metals: Gold, Silver, Platinum
• Material format(s): Powder
• 3D printing technology: Direct Metal Laser Sintering (DMLS) and Material Jetting

Refractory metals

Refractory metals are extremely resistant materials with an incredibly high melting point. This same high melting point combined with their low thermal expansion, high strength, and hardness make them suitable for high-tech applications and power electronics. They also feature a high thermal and electrical conductivity mixed with high wear resistance.

While tantalum and niobium are mainly used in the medical industry for their biocompatibility, good oxidation, and chemical stability, tungsten and molybdenum are preferred for applications such as aerospace, automotive and nuclear applications due to their high density and radiation screening capabilities.

Due to the high density of some of these materials (such as Tungsten), it is necessary to use less common 3D printing technologies, such as electron beam melting (EBM) or even selective deposition of a liquid agent to bind the powder, instead of traditional laser-based printers.

• Commonly used metals: Tantalum, Niobium, Molybdenum, Rhenium, and Tungsten
• Material format(s): Powder
• 3D printing technology: Electron-beam melting (EBM), Laser Beam Melting (LBM), Binder Jetting