Microstructure and properties of GTAW welded joint of 2195 Al-Li alloy in different forming states

GTAW butt welding was carried out using spray-deposited 2195 aluminum-lithium alloy spinning and forging materials. The tensile strength and Vickers hardness of the joint were measured, and the metallographic microstructure and fracture morphology of the joint were observed. The EBSD characterization and statistical analysis of micro characteristic quantity were carried out for each area of the joint. The correlation between microstructure and mechanical properties of the joint was discussed. The results show that the spinning and forging materials have good GTAW processability, the tensile strength of the joint reaches 71% and 68% of the respective base materials, the elongation reaches 7.3%, and the tensile fracture shows ductile fracture characteristics. The proportion of low angle grain boundary of the metal in the joint weld zone is relatively low. The proportion of low angle grain boundary close to the spin side is 6.4%, and the proportion of low angle grain boundary close to the forging side is 7.8%. The heat affected zone between the spin side and the forging side and the fusion zone tend to similar microstructure. The average grain size of the base material, heat affected zone, fusion zone and weld metal are in order of 10, 10 − 15, 15 − 23, 20 − 25 μm, with the better "continuity" of the structure. The fine grain size and uniform composition of the base material are maintained during the welding process, which to a certain extent shows the application advantages of spray-deposited aluminum-lithium alloy materials. Copyright © 2021 Transactions of the China Welding Institution. All rights reserved.