In the aerospace field, welding serves as the primary joining process for TA3 alloy components,and the microstructure and mechanical properties of its welded joints have a significant impact on the service safety of welded components. This study compares the tensile properties of the base metal and welded specimens and studies the deformation morphology before and after tension using scanning electron microscopy combined with electron backscatter diffraction. The results show that the microstructure of TA3 alloy is equiaxed α grains before welding, and massive, acicular and serrated α grains appear after welding. The yield strength (378 MPa) and tensile strength (458 MPa) of welded specimens are higher than that of base material specimens, but the elongation is lower. The reason is that after the base meterial sample is welded, the welding temperature has the effect of aging treatment on the sample. There exists aging hardening, and the grain size inside the weld area becomes smaller, which will increase the tensile strength. Because the microhardness of the weld zone is obviously higher than that of the base metal zone, the fracture of the welded joint is located in the base meterial zone. The deformation mechanism of the weld zone is stress-induced deformation twin (2)[3] and (12)[13], with a Schmid factor of 0.038, exhibiting high shear stress and strong coordination of grain deformation. Deformation twins (2)[3] also appear in the base material region, but the Schmid factor is 0.078, indicating a relatively high degree of stress concentration.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |