MOSCOW, Russia / EuroWire.IO / – Researchers from Russia and China have pioneered an ultrasonic welding method that effectively doubles the tensile strength of metal joints. Additionally, this approach extends the lifespan of welded parts by a factor of 1.9. The development was led by scientists at South Ural State University in Chelyabinsk, collaborating with partners from China. The findings, as reported by TV BRICS and citing the university, focus on joints involving metals with contrasting properties, such as steel and aluminium.
Achieving reliable connections between different metals has historically posed difficulties for engineers. The formation of brittle intermetallic layers at the interface often results in cracks under stress, weakening the overall structure. This new technique specifically aims to minimize such issues during spot welding, a common process used to join metal sheets in automotive bodies and various assemblies. The university announced that the research was published in Engineering Fracture Mechanics.
The innovation involves adding ultrasonic vibrations with an output of approximately 1,200 watts to the standard spot welding procedure. This vibration process refines the crystal structure within the weld, leading to a reduction in crystal size by nearly five times, resulting in smaller and more uniform crystals instead of coarse structures. Furthermore, the method cuts the thickness of the brittle intermetallic layers at the joint by half, reducing their propensity to crack.
Ultrasound eliminates trapped air bubbles in welds
The application of ultrasound also assists in removing air bubbles from the metal during welding, producing denser joints with fewer internal flaws. Testing revealed that the strength of these joints doubled compared to traditional methods. Correspondingly, the lifespan of components increased by 90%, or 1.9 times. The researchers noted that such welds are better suited to withstand prolonged vibrations and mechanical loads without developing cracks. This improved fatigue resistance is essential for parts used in moving vehicles.
In its announcement, the university did not specify exact strength measurements or detailed testing parameters, instead reporting the improvements in relative terms. The scientists described their approach as a means to enhance the reliability of structures made from mixed metals. Combining steel with aluminium is a common strategy to reduce weight while maintaining strength, yet weak joints have historically limited these designs. The project was conducted jointly with Chinese colleagues.
Potential for lighter vehicles, aircraft, and infrastructure
According to the researchers, this ultrasonic welding technology could find applications across automotive, aerospace, and construction sectors. In the automotive industry, it could be used to connect a steel safety cage with aluminium doors, bonnets, and wings. Lighter hybrid structures might enable electric cars to travel longer distances per charge. In aviation, reducing weight allows aircraft to carry more passengers or cargo while consuming less fuel. Both industries prioritize weight reduction as a key objective.
In the construction field, the method could improve metal joint integrity in bridges and skyscrapers. The university indicated that such joints could potentially outperform monolithic concrete in strength. The timeline for industrial adoption remains unspecified. South Ural State University has reported several applied research initiatives this year. Overall, the university believes that this method could lead to the development of lighter and more durable structural components.