Do you know all the 3D printable metals that exist today? We have counted most of the available products for metal 3D printing (over 200 different products) in our latest market report on Metal AM Market Opportunities and Trends 2021. With the data collected, we were able to provide an analysis of revenues and demand, along with a ten-year forecast of all metal AM materials demand through 2030.
Iron and steels were the first and are still the most widely used, with high-end materials such as titanium, Inconel and cobalt-chromium later proving ideal for AM. Now, the new frontiers are challenging (to 3D print or sinter) but widely used materials such as aluminum and copper as well as fringe metals such as refractory metal, precious metals and amorphous metals.
Here’s a summary of the different 3D printable metals and metal alloys that we considered in our study, representing nearly the entirety of metals and metal alloys that can be 3D printed today
Steels were the first 3D printable metals used for additive manufacturing, and today a large and rapidly increasing number of different steels can be processed by AM. The different matrix microstructure components and phases (austenite, ferrite, martensite) and the various precipitation phases (intermetallic precipitates, carbides) lend a huge variability in microstructure and properties to this class of alloys.
This includes austenitic, duplex, martensitic and precipitation-hardening stainless steels, TRIP/TWIP steels, maraging and carbon-bearing tool steels and ODS steels. The most common steels used across various AM processes are 316L and 304 austenitic stainless steel; 17-4PH and 15-5PH martensitic precipitation hardened stainless steel; and 18Ni300 (1.2709) maraging steel and H13 tool steel.
The newest frontier of steel is represented by leveraging the corrosion-resistant properties of certain alloys: for example with super duplex steels from Sandvik, and with a new high-entropy allow from Oerlikon.
The most common austenitic stainless steels used for powder-based AM processes are 316L stainless steel (1.4404) and 304/304L stainless steel as a possible alternative. Both are available for L-PBF, L-DED and binder jetting processes. In these steels, the high chromium content leads to good corrosion resistance, while the nickel additions keep the microstructure of the alloys fully austenitic in conventionally produced materials.
The most common precipitation-hardened (PH) steel in use in powder-based AM today is 17-4 PH, used in L-PBF, L-DED and binder jetting processes. Along with 15-5 PH, used in L-PBF, these steels are considered fully martensitic grades. Also in this category is EOS’ proprietary Stainless Steel CX product. Most bound metal processes and filament materials support both 316L and 17-4PH and stainless steel. 316L is also in development for cold-blown powder (kinetic consolidation) technology.
There are two kinds of tool steels in use in AM, namely carbon-free maraging steels and carbon-bearing tool steels. In both kinds of tool steel, the final microstructure consists of martensite with precipitates. Tool steels are high-quality carbon and alloy steels that are commonly used to make cutters, reamers and bits used for machining. The most prominent examples of carbon-bearing tool steels used in L-PBF AM are the high-speed steels M2 (1.3343), also available for metal binder jetting from ExOne. Cold work steels A2 and the hot working tool steels H13 (1.2344) are also used in L-PBF, binder jetting and some bound metal systems. Some bound metal processes and materials also support D2 steels.
The most widely used maraging steel alloy in L-PBF AM is 18Ni300 (1.2709). Overall, the mechanical properties of AM-produced maraging steel are comparable to conventionally produced material.
Titanium and titanium alloys
Titanium and titanium alloys have for several reasons emerged as ideal materials for many additive manufacturing processes and applications. First, AM uses less total material than other processes, making it more cost-effective to implement in a number of applications. This is especially true in segments such as aerospace, medical (orthopedic implants) and luxury automotive or motorsports, as well as for professional sporting equipment, where the high final cost of the part amply justifies the use of more expensive material to obtain advantages in terms of lightweighting, increased strength and durability.
Titanium alloys are biocompatible and corrosion-resistant, making them an inert biomaterial that can be implanted in the human body. Commercially pure titanium and its most common alloys are commonly used in additive manufacturing for orthopedic implants. Today, the most commonly used titanium alloy in AM of orthopedic implants is Ti6Al4V (Ti64), but CPT has superior corrosion resistance and biocompatibility and is regarded as the metal most compatible with the human body.
Most major AM processes—both powder and wire-based— support titanium alloys as standard consumables. Titanium is also available in bound metal filament form for bound metal printing processes (for example from The Virtual Foundry); however, this material is not at all common among the most widely used bound metal printing platforms today. GE Additive/Arcam–owned AP&C, a major producer of plasma atomized metal powders for AM, has developed titanium aluminide (Ti48Al2Cr2Nb or Ti4822) specifically for aerospace part production via EBM technology.
Aluminum and aluminum alloys are considered the most interesting materials for the next phase of AM growth into large batch and serial production applications. This is due primarily to aluminum’s excellent mechanical properties and low price when compared to similarly lightweight 3D printable metals such as titanium. However, this vision, while in progress, is still far from realization due to several inherent challenges in producing and processing aluminum by AM processes.
One major challenge is that almost all aluminum alloys used in AM today were originally developed for casting applications. In fact, the most common aluminum alloy used in AM by far is AlSi10Mg, an age-hardening aluminum alloy with good hardness, strength and dynamic toughness, which is traditionally used as a casting alloy. Another popular aluminum alloy for AM that was initially developed for casting is A20X.
Only very recently have the first AM-specific aluminum alloys begun to appear on the market. The first one was Scalmalloy, developed and marketed by aerospace specialists APWORKS. RUSAL, one of the world’s largest aluminum manufacturers, launched the ALLOW series of aluminum products for AM which include both casting alloys and several alloys developed specifically for AM processes. Among these are RS-230 AlCu (a hot crack-resistant 2xxx series alloy) and RS-390 AlSiNi alloys, which are suitable for applications up to 250 °C; and RS 507 AlMg and RS-553 AlMgSc alloys, which are corrosion-resistant, high-strength materials marketed at a significantly lower price than Scalmalloy.
Aluminum is challenging to sinter in a furnace as the oxide layer surrounding the particles can only be removed at extremely high temperatures, while aluminum has a relatively low melting point, which restricts the maximum sintering temperature. It is therefore very challenging to remove the oxide layer on the aluminum powder before the entire metal piece has melted. Solutions to this issue have been explored for several years, but commercialization of aluminum as a material for binder jetting remained beyond reach until, in early 2021, both metal binder jetting companies Desktop Metal and ExOne achieved major breakthroughs in the sintering of aluminum 6061 for parts produced by binder jetting technology.
Aluminum alloys could also prove to be valuable and very cost-effective materials for high-throughput WAAM processes. The use of various aluminum alloys in WAAM is currently an actively researched field. The AM materials portfolio of voestalpine Böhler includes a non-specified aluminum wire for WAAM.
Nickel alloys and especially certain proprietary superalloys, such as Inconel, Hastelloy and Waspaloy, represent one of the most commercially interesting and high-growth areas of material development for additive manufacturing in the short and medium term. Nickel superalloys are particularly attractive for use in the energy generation/oil & gas segment.
Inconel and Incoloy have registered trademarks of Special Metals Corporation. Inconel refers to a family of austenitic nickel-chromium-based superalloys and is the most common family of nickel superalloys used in AM processes. Inconel alloys are resistant to oxidation and corrosion and well suited for service in extreme environments.
Today Inconel 625 and 718 are very widely used in all major powder-based AM processes and particularly popular in PBF processes. Inconel 718 is also available from AP&C as a material for Arcam EBM and from ExOne as a qualified material for its binder jetting technology. Inconel 625 is available for all common bound metal hardware. Both Inconel 625 and 718 are available as standard materials for all DED processes (L-DED, EBAM and WAAM). A new Inconel superalloy, Inconel 939, has recently been released by EOS. It is a nickel-chromium alloy that has been strengthened to increase weldability, making it well suited for AM.
Hastelloy (milled by Haynes International) is another Inconel alloy that is gaining popularity in L-PBF additive manufacturing. It is a nickel-molybdenum alloy used in severely corrosive environments. Waspaloy is a registered trademark of United Technologies Corporation that refers to an age-hardening austenitic nickel-based superalloy. This material has recently been qualified for use in L-PBF processes by Rosswag Engineering.
Another emerging material is Nitinol, a nickel-titanium superalloy. Offered by GKN Powder Metals, Nitinol (NiTi) is widely used in medical devices. Carpenter Technologies (through the acquisition of LPW) is working on the optimization of Nitinol for additive manufacturing, developing parameters for controlling the shape memory and elastic properties of this superalloy.
Cobalt-based alloys are often overlooked as a key material for additive manufacturing. However, their use in areas like orthopedics, aerospace, power generation and the dental field is significant.
Used with all major AM technologies and supported by nearly all major PBF platforms, ASTM F75 CoCr is a non-magnetic cobalt-chrome alloy made for good performance at high temperatures, strength, corrosion resistance, wear resistance biocompatibility.
Produced and developed as AM powders for PBF by Kennametal, cobalt-based Stellite alloys are some of the most well-known cobalt alloys in the world.
Copper and copper alloys
Copper is one of the most exciting materials for AM today, although the use of copper and copper alloys in AM was almost non-existent just a few years ago. The use of pure copper in PBF was thought to be impossible because of the high reflectivity and infrared thermal conductivity of the material, which made it too difficult for it to absorb enough energy for a proficient selective laser melting process. Early developers of copper AM materials like GKN gradually introduced copper alloys for L-PBF, but they were not as efficient as pure copper in terms of conductivity.
In 2017, the Fraunhofer Institute for Laser Technology ILT in Aachen, Germany presented an L-PBF method that used a green laser light with a wavelength of 515 nm which resulted in much higher absorptivity of pure copper. This meant that a lower laser power output was needed for a stable process. Furthermore, the laser beam could be focused more precisely, allowing it to fully exploit the geometric benefits of the AM process.
Today, most major L-PBF platforms support copper as a standard material. In 2019 Arcam introduced pure copper as an in-development material for its EBM systems, which are inherently suited to the material. According to GE Additive, pure copper can absorb 80% of an electron beam’s energy—it only absorbs 2% of the energy of a red laser beam—which leads to higher productivity.
All commercial binder-based processes also support pure copper 3D printing, with Digital Metal the latest to validate this material for its binder jetting systems. Binder jetting leader ExOne and bound metal segment leaders Markforged and Desktop Metal all support pure copper.
Refractory metals are a class of metals that are extraordinarily resistant to heat and wear. They include niobium, molybdenum, tantalum, tungsten and rhenium, all of which share some properties, including a melting point above 2,000 °C and a high level of hardness at room temperature. They are chemically inert and have a relatively high density. Their high melting points make powder metallurgy the method of choice for fabricating components from these metals, and the emergence of AM is seen as a true paradigm shift in terms of developing complex refractory metal parts without the limitations of MIM. However, their very high melting point also makes these materials challenging to 3D print.
The commercial use of refractory metals in AM, almost exclusively in L-PBF and some DED processes, has grown significantly over the past five years, with some AM material firms such as ATI, Taniobis, H.C. Starck, Heraeus, Dunlee, Global Advanced Metals and Global Tungsten & Powders (GTP) focusing on all or some refractory 3D printable metals. Even EOS now offers EOS Tungsten W1, a pure tungsten alloy, as a standard material for its systems.
One of the most widely appreciated refractory 3D printable metals is molybdenum, which is used in L-PBF. Spherical molybdenum powder is available for L-PBF primarily from firms such as Tekna, H.C. Starck, Global Tungsten & Powders (GTP) and Heraeus. Metal binder jetting of molybdenum has also been qualified at an R&D level by ExOne. Furthermore, ExOne and Global Tungsten & Powders (GTP) entered into a collaboration in 2019 to qualify tungsten-based metal 3D printing using binder jetting.
Tantalum has potential for use in the orthopedic implant industry for its superior cytocompatibility and biocompatibility compared to Ti-64. Tantalum AM powder suppliers include Taniobis, Metalysis, Tekna, Pyrogenesis and LPW (now part of Carpenter Technology).
Niobium additive manufacturing shows potential for exotic applications in space, energy and research, with AM a sought-after manufacturing method in these application segments due to its increased geometric freedom in part design. Taniobis and Heraeus have been proficiently producing niobium AM powders using various forms of gas atomization technology, while ATI Specialty Materials has developed a proof-of-concept niobium rocket engine nozzle.
EBAM wire-based DED technology from Sciaky also supports tantalum, niobium and tungsten.
Exploration of other refractory 3D printable metals is ongoing and mainly focuses on vanadium and rhenium (mostly as an alloying element for precious metals).
There are several precious metals that can be used for AM. L-PBF and some bound metal printing systems can process silver, and L-PBF can also process gold (rose, red, white, yellow, etc.), platinum and palladium. Silver can be found in nanoparticle inks for 3D printed electronics, palladium is used in industrial applications, while other precious metals are mostly used for jewelry. Less common precious metals for AM include rhodium and iridium.
There are five primary precious metal powder suppliers or service providers catering to the additive manufacturing industry today. UK-based Cooksongold can be considered the leader in this segment, having co-developed a precious metal L-PBF system, the Precious M 080, with EOS. Cooksongold offers precious metal production services and a selection of materials that includes 18K yellow, rose and white gold; 14K yellow gold; 925 sterling silver and 950 Platinum/Ruthenium. Italy-based Legor has also developed an AM-specific line of metal AM powders called POWMET which includes the same alloys with the addition of 24K gold and other less precious powders such as bronze, brass and copper. Other precious metal segment leaders such as Progold3D and Heraeus specialize in offering end-to-end precious metal AM production services.
An amorphous metal is a solid metallic material, usually an alloy, with a disordered atomic-scale structure. Most metals are crystalline in their solid state, which means they have a highly ordered arrangement of atoms. Amorphous metals are non-crystalline and have a glass-like structure. But unlike common glasses such as window glass, which are typically electrical insulators, amorphous metals have good electrical conductivity.
German firm Heraeus has invested more than any other company in amorphous 3D printable metals. In 2019, the company presented a gear wheel, 3D printed using its own amorphous metal material and a standard L-PBF system, that broke the world record for the largest part made from amorphous metal. Heraeus’ AMLOY AM business unit has since partnered with machine manufacturing company TRUMPF to further advance the 3D printing of amorphous metals using the TruPrint 2000 system. The L-PBF system from TRUMPF prepares excess powder for the next build in an inert gas environment, which protects the particles from any external influences.