Investigation of the Dynamic Strain Aging Effect in Austenitic Weld Metals by 3D-DIC

Austenitic stainless steels similar to type AISI 316L are widely used structural materials in current and future nuclear reactors. Careful development and characterization of these materials and their welds is needed to verify the structural integrity of large-scale multicomponent structures. Understanding the local deformation behavior in heterogeneous materials and the mechanisms involved is key to further improve the performance and reliability of the materials at the global scale and can help in developing more accurate models and design rules. The full-field 3D digital image correlation (3D-DIC) technique was used to characterize two 316L multi-pass welds, based on cylindrical uniaxial tensile tests at room temperature, 350 degrees C, and 450 degrees C. The results were compared to solution annealed 316L material. The inhomogeneous character and dynamic behavior of the 316L base and weld materials were successfully characterized using 3D-DIC data, yielding high-quality and accurate local strain calculations for geometrically challenging conditions. The difference in character of the dynamic strain aging (DSA) effect present in base and weld materials was identified, where local inhomogeneous straining in weld material resulted in discontinuous type A Portevin-Le Chatelier (PLC) bands. This technique characterized the difference between local and global material behavior, whereas standard mechanical tests could not.

Automated summary

Austenitic stainless steels, such as AISI 316L, are widely used in nuclear reactors and their development and characterization is crucial for ensuring structural integrity. The 3D-DIC technique was successfully used to characterize the behavior of multi-pass welds and base materials, providing accurate local strain calculations. The difference in dynamic strain aging effect between the base and weld materials was identified, with the weld materials showing discontinuous type A PLC bands. This technique allows for a better understanding of the local and global behavior of materials.