Effect of fluid in molten pool on the welds with Ti-6Al-4V during pulsed arc welding

Abstract

Titanium alloy is one of the most popular materials in engineering applications. Pulsed arc welding can obtain grain refinement of titanium that is a benefit for mechanical properties. However, the study found that the optimized effect decreased with some higher frequencies. Hence, the study of Ti-6Al-4V was carried out with higher-frequency region, and the reason was discussed. The fluid of molten pool had effect on microstructure and mechanical properties of welding joints. Simultaneously, the arc behavior with pulsing current was known as the important factor for the fluid status. Thus, the microstructural morphology, microhardness gradient, and mechanical properties were detected, which were also compared with other frequencies. With high frequency more than 50 kHz, the fluidity of molten pool decreased significantly with low ductility of joints. The mechanism simulation was produced with plane and ellipsoid assumptions, and the results indicated that the conflux caused impact region of double circulation, which was recognized as the main reason for the drops of microstructure and properties with more than 50 kHz.

Analysis of process parameter effects during narrow-gap triple-wire gas indirect arc welding

“…One is that the arc pressure of the GTA can directly pushes the liquid metal towards the sidewalls [16], forming the favorable weld bead formation. The other reason is that the GTA inputs extra heat in the weld pool, which can enhance the fluidity of the liquid metal [17]. Figure 12 shows the microstructure when a GTA is added to the TW-GIA.…”

Study on arc shape, weldment microstructure, and mechanical properties of Ti-6Al-4V welded by FFDP TIG waveform

“…Researchers have applied high frequency pulsed current to improve weldment microstructure and mechanical properties. Yang et al [16] studied the high-frequency pulsed arc welding of Ti-6Al-4V alloy at the frequency of 10-80 kHz, the elongation and fracture shrinkage were increased. Zhou et al [17] indicated that the low heat input of high frequency pulse welding was conducive to obtaining refined grain size, dense martensite αʹ organization and better tensile property.…”

Research on the Formation, Microstructure, and Properties of 304 Stainless Steel AC-DC Hybrid TIG Welding

“…Mingxuan Yang et al showed that the arc characteristics under pulsed current affect the molten pool fluid state which affects the microstructure and mechanical properties of welded joints. Additionally, the pulse frequency can optimize the mechanical properties of welded joints, such as toughness and ductility [23]. Wang, Y. J. et al showed that the high frequency pulse can produce an ultrasonic effect on arc and molten pool, and the amplitude of modulated pulse current is the main factor affecting ultrasonic sound pressure and power [24].…”