CuNi: the metal of maritime AM
With more and more AM companies developing and qualifying CuNi materials, the growing importance of maritime end users is clearer than ever
This article was originally published in VoxelMatters’ Metal AM Focus 2025 eBook. The full edition can be found here.
In the maritime industry, particularly in the shipbuilding segment, material choice is a critical consideration. While in industries like aerospace, minimal weight and high-temperature resistance are a top priority, in the maritime sector, corrosion resistance and durability are the most essential material properties. It makes perfect sense: components on a ship must be able to withstand the harsh environment at sea, including the corrosive nature of sea water, while also offering structural integrity and a long lifespan.
For those reasons, the maritime industry has gravitated towards a relatively small selection of metal types, including steel (ship hulls are constructed from steel, for instance), aluminum (used for superstructures and non-structural components to maximize fuel efficiency), Inconel (used for propeller blades and scrubbers) and other superalloys. In the growing maritime AM subsegment, a small number of specific alloy types have risen to the top and chief among them are copper–nickel alloys (CuNi).
CuNi alloys are already well established in the maritime industry. The metals, known for their excellent corrosion resistance and low macrofouling rates, have various applications in offshore, naval and shipbuilding segments, including desalination systems, piping, heat exchangers, condensers and more. While most CuNi parts in maritime are manufactured using more traditional methods like casting, additive manufacturing is increasingly becoming a viable option as companies in the AM industry develop and validate CuNi for various metal 3D printing processes. This is particularly important considering that cast CuNi alloys can be plagued by challenges like cracks and porosity, which necessitates rework, ultimately driving up costs and lead times.
Being able to additively manufacture CuNi parts offers shipbuilding and naval organizations several benefits, including unlocking more rapid production times (eliminating the need for tooling), reducing reliance on large inventory stocks, simplifying supply chains and manufacturing more efficiently designed components. On top of that, AM enables more sustainable practices through the minimization of material waste and more localized production, which reduces emissions associated with logistics. Technologies like directed energy deposition (DED) are also making it possible to repair existing components additively, which has benefits when it comes to sustainability (extending the lifespan of large parts) and cost.
Within the AM industry, only a small number of companies currently offer copper-nickel alloy materials. It is worth pointing out, however, that though the group is small, it is growing, with new CuNi products being launched and validated in the past year. This recent growth just goes to show how the metal AM industry is recognizing the big potential of maritime as an AM adopter.
The first CuNi alloy developed specifically for maritime additive manufacturing was introduced in 2022 by 3D Systems. The material, CuNi30, was developed for the company’s DMP Flex 350 platform through a collaboration with HII’s Newport News Shipbuilding division. The material reportedly results in parts with superior density and mechanical properties compared to cast parts—all without the need for tooling—and demonstrates stability over a broad range of temperatures (from 400 °C to -270°C). These properties make CuNi30 suitable for a range of maritime (and adjacent) applications, like ship pipe fittings, valves and pumps; off-shore oil and gas components; chemical and nuclear equipment; and even cryogenic systems.
The introduction of the material enabled Newport News Shipbuilding to exploit the benefits of LPBF for its low-volume, high-mix part requirements. At the time of the material launch, the end user anticipated a dramatic 75% reduction in lead times and lower inventory costs compared to their conventional casting workflows.
Since the release of 3D Systems’ certified CuNi30, German 3D printing leader EOS has also developed its own CuNi30 powder for LBPF, with a nickel content of 28–32%, and small amounts of niobium, iron and manganese. The copper-nickel alloy, which launched commercially in early 2024, offers a range of properties suitable for maritime applications, such as excellent strength with up to 700 MPa in heat-treated horizontal builds, and ductility with around 510 MPa UTS and more than 20% elongation.
The alloy was developed and validated in cooperation with Philips Federal and Austal USA for the Submarine Industrial Base (SIB). Specifically, EOS developed the material with the aim of “alleviating supply chain pressures” on traditional cast components for the 2+1 Columbia and Virginia Class submarine platforms for the US Navy. The AM-grade material conforms to UNS C96400 specifications in ASTM B369-09 and offers the same level of corrosion resistance as cast CuNi components without the manufacturing woes. In terms of application, EOS’ CuNi30 is ideal for a range of maritime components, including pumps, impellers, submarine seawater intake valves, high-pressure piping and propulsion hardware.
In 2024, ADDMAN Group, through its Harbec business unit, entered into a partnership with the US Navy to qualify CuNi components for submarines. This qualification effort is ultimately aimed at establishing AM as a viable production method for CuNi parts in order to accelerate procurement cycles and improve overall part quality. For the US Navy specifically, 3D printed CuNi could meet its “2+1” submarine production targets.
In the last five months, at least three new efforts to qualify copper-nickel alloys for additive manufacturing have arisen with the aim of furthering AM applications in the maritime and defense (specifically naval) sectors. Australia-based AML3D, a specialist in Wire Additive Manufacturing (WAM) announced in May that it had signed a $1.01 million purchase order with BlueForge Alliance, a nonprofit integrator that supports the US Navy’s Submarine Industrial Base, to develop and qualify CuNi alloys for defense applications. This follows a successful characterization of a CuNi alloy in 2023, which was part of a US Navy submarine qualification program.
In the same month, UK-based metal AM company Renishaw revealed it had teamed up with Austrian metal powder manufacturer Metalpine to develop and qualify CuNi powders to enable a “major European naval force” to produce replacement parts in-house. Specifically, the partners developed process parameters for CuNi 10 (which is composed of 90% copper and 10% nickel) and CuNi 30 (70% copper, 30% nickel).
“With these precise settings we have overcome the material’s challenges, ensuring high-quality, durable parts that can withstand harsh marine environments,” said Alex Garcia, AM Design and Applications Engineer at Renishaw. “This optimization enhances part strength and longevity and ensures consistent results, allowing our naval customer to manufacture parts that perform reliably under tough conditions.”
More recently, American metal AM company Velo3D announced the development and qualification of a CuNi alloy for its Sapphire 3D printer series. The development, formalized through a $6 million contract, will support the US Navy Maritime Industrial Base in the repair of critical ship structures and components. Notably, Velo3D says this contract will make it the first American OEM to qualify CuNi for its domestically developed 3D printers, including the large-format Sapphire XC 3D printer.
The CuNi development process is being led by Velo3D’s team in Fremont, California, which will develop process parameters for a powder supplied by a domestic, openly sourced metal powder provider (a necessary consideration in order to maintain supply chain independence for the US Navy.”
Ultimately, the development of CuNi alloys for AM processes and platforms will only benefit end users from the maritime and naval sectors, as they can not only leverage the advantageous properties of the material, but also the inherent assets of AM, including design freedom, production agility and material efficiency.
