Wire Arc Additive Manufacturing in Maritime: Opportunities, Limitations, and Lessons Learned

Wire Arc Additive Manufacturing (WAAM) has attracted increasing attention as industries seek faster, more flexible routes to producing critical parts. With higher deposition rates than powder-bed processes and the ability to handle large build volumes, WAAM offers unique advantages for maritime and energy applications.

Nevertheless WAAM is not a universal solution. It has limitations that engineers must understand and opportunities that, if applied correctly, can deliver commercial and technical benefits. At Pelagus, our role is to ensure OEMs receive a balanced, engineering-led perspective on when and how WAAM should be deployed.

What WAAM Offers

WAAM uses an electric arc combined with wire feedstock to build near-net shape parts. It sits within the ISO/ASTM definition of Directed Energy Deposition and is sometimes described as “3D welding.”

For maritime and energy applications, its strengths are clear:

• Shorter lead times: Design to installation can be achieved in 4–8 weeks, compared to many months for conventional casting or forging.
• Low production volume efficiency: WAAM is cost-effective for single parts or small batches where traditional methods would require uneconomical minimum order quantities.
• Material sustainability: Less waste compared to machining from raw material, cost -effective especially for expensive alloys.
• Large component capability: High deposition rates in WAAM enables very large components to be produced more quickly than powder-based methods.

Material Observations

Materials that can be processed via WAAM are similar to those used in welding. Metallic alloys such as carbon steels, stainless steels, nickel alloys, aluminum alloys, titanium and copper alloys such as Nickel Aluminum Bronze have been successfully manufactured with WAAM. WAAM offers higher material density, superior strength and toughness than castings, and can produce more intricate shapes than forging.

Opportunities in Maritime and Energy

WAAM aligns with industry needs in several ways:

• Legacy component replacement: Large sized, relatively complex geometries where forging lead times are prohibitive.
• Operational flexibility: OEMs can avoid stockpiling slow-moving replacement parts and instead produce on-demand.
• Sustainability: Reduced material waste and shipping by enabling localized production near the point of use.
• Qualification pathways: Standards such as DNV-ST-B203, AWS D20.1, and API 20S provide clear frameworks for part acceptance, reducing uncertainty for OEMs.

Limitations Engineers Must Acknowledge

WAAM is not a “do everything” process. Its limitations are as important as its strengths:

• Surface finish: WAAM parts require final post-machining to meet dimensional and surface specifications.
• Distortion and residual stress: Complex thermal cycling means that careful control of preheat, heat input, mechanical restraints and post-build stress relief heat treatments may be required for distortion and residual stress management.
• Porosity and inclusions: Must be mitigated through parameter tuning, interlayer cleaning and qualified inspection regimes.
• Microstructural imperfections: For some materials, the thermal gradient from the WAAM process produces columnar grains and elemental segregation which can result in different properties in comparison to fine-grained wrought materials.

For OEMs, understanding these limits is essential. Misapplying WAAM can result in poor performance, wasted financial investment, and erosion of confidence in additive manufacturing solutions.

Case Study: Side Thruster Propeller Blade

In collaboration with Kawasaki Heavy Industries and BW Epic Kosan, Pelagus produced a 55 kg nickel-aluminum bronze side thruster blade using WAAM.

• Build time: 4 weeks (design to delivery)
• Post-process: Stress-relief heat treatment and CNC machining
• Testing: Dye penetrant and ultrasonic testing (with calibration block), tensile, charpy impact, hardness, bend tests, microstructure evaluation
• Certification: Qualified to DNV ST B203 AMC 2, with EN 10204 3.2 certification witnessed by DNV

The blade has been in service for two years without operational issues. Strength was ~40% higher than the original casted part.

This case demonstrates WAAM’s suitability for large cast-equivalent components where testing, qualification, and post-processing are rigorously applied.

RELATED: Side Thruster Propeller Replacement During Vessel Dry-Dock

The Role of Pelagus

As a technology-agnostic partner, Pelagus reviews designs, considers manufacturability, and recommends the most suitable process such as WAAM, rapid casting, laser powder bed fusion, or machining. Our engineers challenge assumptions, oversee requirements, and protect OEM standards from start to finish. This is the value that instant-quote platforms cannot offer OEMs.

WAAM offers OEMs a practical way to shorten lead times and extend support for legacy part portfolios. But its value ultimately lies in applying it where it fits, not in overselling the technology in the wrong context.

Author Bio

Dr. Cui Er Seow is Manufacturing & Supply Chain Manager at Pelagus 3D. She holds a PhD in Mechanical Engineering from the University of Bristol, specializing in Wire Arc Additive Manufacturing of nickel-base alloys. Previously a Senior Additive Manufacturing and Welding Engineer at TWI, she now works with OEMs to apply advanced manufacturing processes across the Pelagus global supply chain.