HEAVY-DUTY
TRANSFORMING NEXT-GENERATION HEAVY-DUTY STEEL APPLICATIONS
for demanding heavy-duty steel applications. Invented at TWI
R in the early ‘90s, FSW
ichard Townsend, Commercial Lead – Friction Stir Welding, Element Six talks to Welding
World about how Friction Stir Welding is transforming next-generation heavy-duty steel applications. For decades, heavy-duty steel structures
in sectors such as energy, shipbuilding, pipelines, automotive and aerospace have relied on conventional arc and fusion welding processes. However, this entails significant compromises in distortion, residual stress and defect risk, particularly as plate thicknesses increase and alloys become more complex. As the industry seeks higher productivity, tighter tolerances and more demanding service environments, those compromises are becoming increasingly difficult to accept. Friction stir welding (FSW), pioneered
by The Welding Institute (TWI) and enabled by Element Six’s (E6) advanced polycrystalline cubic boron nitride (PCBN) tooling, is now emerging as a proven, high- integrity and production-ready alternative
is already well established in aluminium fabrication, whereas until recently steel had remained a technical challenge due to the material’s extremely high melting point, as the process demands extreme tool durability, tight thermal control, and precise material flow management. FSW steel requires tools that are strong and stiff at temperatures of over 1,000⁰C, while simultaneously being resistant to oxidation, chemically stable even in contact with hot iron and resilient against the high bending and fatigue loads imposed upon them. The collaboration between TWI and E6 is now opening up FSW to heavy steel fabrication through the use of E6’s innovative PCBN tools integrated in TWI’s POWERSTIR platform.
Why heavy-duty steel needs a new approach In many heavy-duty steel applications, arc and fusion welding can deliver acceptable welds, but only at the cost of high heat input, multiple passes and
26 / WELDING WORLD MAGAZINE - ISSUE 04 - AUGUST 2026
extensive rework. For thick plate and high-alloy steels, this often results in: • Significant distortion requiring straightening, machining or re-fabrication.
• High residual stresses, that can compromise fatigue life and in-service reliability.
• Increased inspection and qualification effort, adding time and cost to projects.
These challenges are even greater for
cryogenic steels. For example, 9% nickel (Ni) must remain tough at extremely low temperatures for applications such as liquified natural gas (LNG) storage and low- temperature energy carriers. Conventional welding of nickel alloys requires filler metals and strict controls on heat and microstructure. This makes the process more complex, expensive and risky for storage tanks and related infrastructure. FSW offers a fundamentally different
approach – a solid-state joining route that minimises peak heat input, reduces defects, and delivers weld properties closer to those of the parent material. This combination is highly attractive for heavy-duty structures where integrity, consistency and productivity are critical.
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