TC4钛合金水下激光填丝焊接工艺研究

Laser welding with filler wire of the TC4 titanium alloy has been successfully applied in underwater field. The underwater laser welding with filler wire of TC4 titanium alloy was researched by adjusting welding speed and wire feed speed to obtain high quality underwater weld metal. After welding, the welding surface appearance and micro forming, as well as the microstructure and mechanical properties of the weld metal under different process parameters are analyzed. The results show that when the welding speed and wire feed speed are 20 mm/s and 60 mm/s respectively, a well-formed and continuously stable weld metal can be obtained. The center of the weld metal is scattered acicular martensite, besides, the heat affected zone can be divided into two parts, they are mainly near the weld metal zone and the close to base metal zone, the α' phase of the close to the base metal zone is less than that of the near the weld metal zone, because the temperature of the close to base metal zone is higher, more β phase change to α'phase. With the increase of welding speed (or wire feed speed), both yield strength and impact toughness of the welded joints show a trend of increasing firstly and then decreasing. When the welding speed is 20 mm/s and wire feeding speed is 60 mm/s, both of them reach the maximum value, the yielding strength is 813.42 MPa and impact toughness is 39.07 J/cm². Larger aspect ratio and cross-sectional area of weld metal can improve the mechanical properties of joints The fractures are surveyed to obtain the surfaces traits by the scanning electron microscope, it can be found that they are mixed fractures of cleavage fracture and dimple fracture.