Influence of Lanthanum-Doped Tungsten Wire Drawing Process on Microstructure and Properties

Abstract

A reasonable preparation processing of Lanthanum-doped tungsten wire plays a decisive role in the final properties of the wire. This paper gives the optimum drawing process parameters of lanthanum-doped tungsten wire with φ1.00 mm–φ0.50 mm and explains the phenomenon of coarsening of fiber-like grains in the preparation processing of tungsten wire. The final optimum process parameters of lanthanum-doped tungsten wire are given: the temperature is 950 °C (the first pass temperature is 950 °C, and the temperature decreases by about 20 °C for each pass), the compression ratio is 15%, mold temperature is 550 °C, because of the limitation of equipment conditions, the wire drawing speed is fixed at 0.19 m/s. It is found that the fiber-like grains of the tungsten wire coarsen when the temperature is too high, and it is prone to breakage when the temperature is too low during the drawing process. When the compression ratio is too high (for example, 22%), there is a negative impact on the surface quality and the straightness of the tungsten wire. When the compression ratio is too low, the processing die time is increased, and the production cost is increased.

Research Status of Manufacturing Technology of Tungsten Alloy Wire

“… EBSD diagram of 0.50 mm tungsten alloy wire cross-section [ 83 ]: ( a ) process 1; ( b ) process 2; ( c ) process 3; ( d ) process 4. …”

“…Michel et al[82] performed tensile experiments on tungsten wires between 25 • C and 320 • C. The experiments showed that the tensile strength of tungsten wires gradually decreased with increasing temperature, and their sectional shrinkage increased from 20% to 55%. Wang Luyan et al[83] prepared lanthanum tungsten alloy wires (ϕ1.00 mm-ϕ0.50 mm) using different drawing process parameters to investigate the effects of different processes on the organization and properties of lanthanum tungsten alloy wires. The controlled mold temperature of each process was 550 • C, and the wire heating temperature (reduced by about 25 • C per pass) was 1050 • C and 950 • C, with the specific parameters shown in Table7.…”