Summary: UCLA researchers in the Departments of Mechanical & Aerospace Engineering and Materials Science & Engineering have developed a novel method for stress reduction in welded alloy materials.
Title: Nanotechnology-Enabled Reduction of Fusion-Induced Residual Stress in Alloys
Background: Fusion welding is commonly used in manufacturing to join two metals with a strong and permanent joint. But welding often leads to high residual stresses (stresses which are present in a body even when no external forces are acting), which can cause distortion and premature failure. Techniques to minimize these stresses can be applied before, during, or after welding, but they are limited in application by complex geometries, plastic deformation in materials, and the cost of implementation, which can include extra fixturing. In destroyer-class ships, distortion caused by residual stress is estimated to cost between $2.4-3.4 million per ship. For jet engine manufacturing, a reduction in distortion-induced part rejection could result in savings of 15-20%. Additional drawbacks of current welding methods include rapid and uncontrolled heat release, and the presence of large, directional grains at the weld interface, leading to non-uniform behavior. Taking into consideration these limitations in the state of the art, there is a clear unmet market need for a cost-effective method of reducing residual stress in welded alloys.
Innovation: UCLA researchers lead by Professor Xiaochun Li developed a method of using nano-treating to reduce solidification-induced residual stress in metal and alloy welding as well as fusion welding-based additive manufacturing. The nanotechnology underlying the invention causes a shift in solidification which affects both thermal behavior and the development of strain without significant modification of current techniques. By controlling outward heat release, the method enables the formation of a refined, homogenous microstructure under welding conditions. As an added benefit, axial strains are also reduced, which further lowers residual stress in the fabricated part. These benefits enable a new manufacturing technique to address welding-induced part distortion and residual stress, significantly aiding various industries by lowering the costs associated with part rework or rejection due to production issues.
Potential Applications: • Aluminum and aluminum alloy fusion welds • Magnesium and magnesium alloy fusion welds • Copper and copper alloy fusion welds • Steel fusion welds • Additively manufactured metal components using fusion welding-based techniques • Heavy industry alloy production (aerospace, automotive, shipbuilding, etc.) • Construction & railway Advantages: • Less unrestrained macroscopic distortion • Controlled outward heat release • Reduced residual strains within joint area • Fine, equiaxial, non-dendritic grains upon solidification • Eliminates the need for extra fixturing, pre-stressing, thermal tensioning, and heat treating
Development-To-Date: Method has been successfully described and characterized.
Related Papers: Fundamental Study on the Arc Welding of Dissimilar Aluminum Alloys with Nano-Treated Filler
Reference: UCLA Case No. 2024-225