MULTI-CYCLE PINCH WELDING OF 304L TUBES: 1NHOMOGENEITIES IN DEFORMATION AND RECRYSTALLIZATION TEXTURES AND MICROSTRUCTURES

摘要

The evolution of textures and microstructures during solid state pinch welding of 304L tubing is studied. Determination of mechanisms responsible for the final texture and microstructure are of significant interest. Results from fully bonded tubes suggest that the central portion of the bond line undergoes dynamic recrystallization while material peripheral to the bond line undergoes static recrystallization. Grain growth does not occur in the bonded region even though the temperatures approach the melting temperature. The texture evolves from an initial {111} fiber texture to a {100} fiber+cube texture. The texture evolution is ascribed to a process similar to strain induced boundary migration (SIBM), where a limited but constant source of dislocations during the pinching and welding operations accumulate more readily in non-{100} grains than in the {100} grains. The stored energy differential biases boundary migration into the non-cube grains.