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May 7, 2026 — A Russian-Chinese research team has unveiled an ultrasonic-assisted welding method that dramatically improves the durability of dissimilar metal joints. Scientists from South Ural State University (SUSU) and partner laboratories in China say the technique can double the strength of welded connections and extend component service life by nearly twofold.
The breakthrough, first reported through the university’s official channels and shared by TV BRICS, addresses a long-standing problem in industrial welding: how to reliably join metals with very different physical and chemical properties, such as steel and aluminium.
When steel and aluminium are joined using traditional spot welding, the interface between the two metals often forms a hard, brittle layer. This intermetallic zone may look solid, but it is highly vulnerable to cracks when the finished part is subjected to mechanical stress, vibration, or temperature changes.
For years, engineers have struggled with this limitation. Hybrid structures made of steel and aluminium offer major advantages in weight reduction, but the risk of fracture at the weld line has limited their use in safety-critical applications.
The SUSU-led project set out to change that by modifying the welding process itself, rather than relying on new alloys or expensive surface treatments.
The key innovation is the introduction of high-power ultrasonic vibrations into the spot-welding cycle. The team applied ultrasonic waves with an output of roughly 1,200 watts while the metal was in a molten state. These waves travel through the liquid weld pool and alter the way the metal solidifies.
According to the researchers, the ultrasonic field causes two important microstructural changes. First, it breaks up large crystals as they begin to form. The average crystal size in the weld zone was reduced by almost five times compared with conventional welding. Second, it suppresses the growth of the brittle intermetallic layer at the steel-aluminium boundary, cutting its thickness by half.
A finer crystal structure means the weld can distribute stress more evenly. This reduces the chance of localized weakness and makes the joint far less likely to fail under repeated loading.
Ultrasonic vibrations do more than refine the grain structure. They also drive dissolved gases and air bubbles out of the molten metal. In ordinary welding, trapped bubbles can leave microscopic voids inside the joint. These voids act as stress concentrators and become starting points for cracks over time.
By removing those bubbles, the new method produces a denser weld with better internal integrity. The result is a cleaner bond line and improved fatigue resistance, which is particularly important for components that experience continuous vibration over long periods.
The university said tests showed the new welding method doubled the overall strength of the joint. In addition, components produced with the technology had a service life 1.9 times longer than those joined by conventional methods. Some samples, the researchers noted, were able to withstand sustained exposure to vibration for years without visible crack formation.
The automotive industry is likely to be among the first to benefit. Car manufacturers are increasingly looking for ways to combine steel body structures with aluminium panels or battery enclosures. Stronger joints between these dissimilar metals make it possible to produce lighter hybrid vehicle bodies without compromising safety.
For electric vehicles, weight reduction is directly linked to energy efficiency. Every kilogram saved can extend driving range and reduce the strain on the battery pack. The ultrasonic welding process could therefore help EV makers improve efficiency without redesigning the entire vehicle platform.
Another potential application is in battery pack assembly, where reliable connections between aluminium and copper or steel are critical for both performance and fire safety.
Aviation is another sector where the technology could have a significant impact. Aircraft manufacturers are under pressure to reduce fuel consumption and carbon emissions, and one of the most effective ways to do that is by reducing structural weight.
The ability to join dissimilar metals with confidence opens up new design possibilities for fuselage sections, wing components, and interior structures. Lighter aircraft require less fuel on every flight, and the freed-up payload capacity can be used for additional passengers or cargo.
Because the ultrasonic method improves fatigue resistance, it is especially relevant for aircraft parts that experience constant aerodynamic vibration and pressurization cycles.
Construction and infrastructure could also benefit. Steel-reinforced structures often need to be connected to aluminium or other non-ferrous elements, particularly in modern architectural designs, bridge decks, and modular building systems.
A stronger, more reliable bond between dissimilar materials reduces the risk of hidden fatigue damage in load-bearing assemblies. That could lead to safer buildings and bridges with lower maintenance costs over their lifespan.
The technology may also prove useful in rail transport, shipbuilding, and the production of heavy machinery, where mixed-metal assemblies are common and downtime is expensive.
The SUSU findings add to a growing body of evidence that ultrasonic-assisted welding is moving from the laboratory to the factory floor. Several international research groups have explored similar techniques, but the Russian-Chinese collaboration stands out for the scale of the reported improvement.
Industry analysts note that the process does not require major changes to existing spot-welding equipment. Adding an ultrasonic generator to a standard welding line is relatively straightforward, which could accelerate adoption in plants that already use automated assembly.
There are still practical questions to answer before the method becomes widespread. Engineers will need to determine optimal ultrasonic parameters for different metal combinations, sheet thicknesses, and production speeds. Long-term reliability data from real-world components will also be important.
Still, the implications are clear. Ultrasonic welding offers a low-cost, scalable way to make mixed-material structures stronger and longer-lasting. As manufacturers search for ways to improve energy efficiency and reduce material waste, that combination of benefits is difficult to ignore.
The research was carried out within the framework of international cooperation supported by TV BRICS and the partner university network, reflecting the growing role of cross-border scientific collaboration in advanced manufacturing.
For now, the technology remains at the development stage, but its potential is well documented. If the results hold up in industrial trials, the next generation of vehicles, aircraft, and infrastructure could be held together by welds that are stronger than the metals themselves.
