AA5052 aluminum alloy and 304 stainless steel with the thickness of 3 mm are welded with ZnAl22 flux-cored wire by tungsten inert gas (TIG) fusion-brazed welding. The effect of different welding currents and wire feeding speeds on the macro morphology of butt joints,microstructure of weld seam/steel interface,tensile properties and fracture behavior of the joints is studied. The results show that when the welding current is 110 A and the wire feeding speed is 24 mm/s,the maximum average tensile strength of the butt joints reaches 166 MPa. Fracture primarily occurs at the weld seam/steel interface, exhibiting typical brittle fracture characteristics. The weld seam/steel interface is composed of η-Fe2Al5Zn0.4,η-Zn(Al) and α-Al. With the increase of the welding current,the tensile strength of the joint first increases and then decreases. The white granular δ-FeZn10 appears in the η-Fe2Al5Zn0.4 interfacial layer,and Zn elements are segregated at the η-Fe2Al5Zn0.4/steel interface. The Zn-rich phases at the η-Fe2Al5Zn0.4/steel interface are determined to be Γ-Fe3Zn10 by transmission electron microscopy. It is found that excessively high welding current leads to cracking at the η-Fe2Al5Zn0.4/steel interface. With the increase of wire feeding speeds,the thickness of η-Fe2Al5Zn0.4 decreases gradually,and the phase composition at the weld seam/steel interface remains unchanged. Based on thermodynamic analysis,it is concluded that the formation sequence of intermetallic compounds (IMCs) at the weld seam/steel interface is η-Fe2Al5Zn0.4,δ-FeZn10,Γ-Fe3Zn10.
| 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 |