New welding filler materials developed in the United States can be used to repair automobile steel parts

According to foreign media reports, the United States Department of Energy and the Department of Defense have jointly developed a series of welding filler materials, which can significantly improve the repair of high-strength steel in automobiles, bridges and pipelines. Such new welding wires can help revitalize the aging infrastructure of the United States. In 2021, the American Society of Civil Engineers rated such infrastructure as Grade C.

Researchers operate welding tools in the welding room (photo source: Oak Ridge National Laboratory of the US Department of Energy)

The invention of the Oak Ridge National Laboratory (ORNL) of the United States Department of Energy and the United States Army can eliminate the need for costly and laborious heat treatment process for field welding, which is usually used to reduce residual stress and material deformation. The invention solves a major problem of steel welding, that is, when hydrogen atoms enter the metal during welding, the ductility, toughness and strength of the metal will be reduced. Subsequently, high tensile residual stress will lead to metal cracking.

Stan David, an honorary retired researcher at ORNL, said: "About 80% of the welded structures in the United States are made of steel, so the filler metals we have innovatively developed are widely used. Repairing structures are cheaper than replacing structures. Our filler materials provide high-quality welded joints, which extend the service life of welded structures in harsh environments. This invention can save hundreds of millions to billions of dollars for American industry every year."

If stronger steel is used to manufacture welded structures, less steel is needed in the process of material manufacturing and vehicle operation, which can reduce weight, save energy, reduce carbon dioxide emissions, and ultimately make more fuel-efficient vehicles, lighter combat vehicles and support vehicles, and more durable fuel pipes. However, strong steel is particularly prone to cracking due to hydrogen.

In order to overcome this challenge, ORNL and scientists from the former US Army Tank Vehicle Research, Development and Engineering Center (now the Ground Vehicle System Center) of the Ministry of Defense jointly developed an alloy with unique chemical composition, which can connect strong steel while reducing residual stress.