A study of Ti-6-22-22S transformation behavior and welding characteristics
- and others
Titanium alloy Ti-6Al-2Sn-2Zr-2Mo-2Cr-0.25Si (nominal composition in wt%, hereafter designated as Ti-6-22-22S) in the form of sheet, plate, forging, and extrusions has been proposed for potential application in advanced aircraft and aerospace systems. The primary objective of the present study was to develop information on the continuous-cooling phase transformation behavior of Ti-6-22-22S and to correlate this behavior with microstructure evolution during welding. In Phase 1, continuous-cooling phase transformation (CCT) diagrams were generated for four heats of Ti-6-22-22S using a Gleeble thermomechanical simulator equipped with a dilatometer. In Phase 2 of the project, electron beam (EB) and plasma-arc welds were characterized. Correlations were developed between the weld energy input, and weld microstructure, and the weld hardness in the context of the CCT studies. Metallographic examination of EB and plasma-arc welds revealed a variety of microstructures that corresponded to microstructure evolution predicted by the CCT work. Relatively high hardness levels (DPH 400{emdash}450 DPH) were measured in both the weld metal and near-HAZ of both weld types. Microstructures in these weld regions were primarily acicular alpha with some colony alpha in higher heat input plasma-arc welds. These microstructures may significantly compromise the toughness and ductility of the weld region and methods for reducing the weld cooling rate are recommended in order to improve these properties.
- OSTI ID:
- 115481
- Report Number(s):
- CONF-9404233--
- Country of Publication:
- United States
- Language:
- English
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