Effect of fast-frequency pulsed waveforms on the microstructure and mechanical properties of Ti–6Al–4V alloy welded by FFP-TIG
Jianwen Wu, Zhenmin Wang, Sanbao Lin, Zhengchao Xie, Mengjia Xu, Jiyu Tian, Chunfu Guo
Abstract
Ti–6Al–4V alloys have been widely adopted because of their good mechanical properties. TIG welding is a common method for Ti–6Al–4V alloys. However, the high heat input of conventional TIG can lead to a coarsening of grains within Ti–6Al–4V and thus a weaker Ti–6Al–4V weld. This study presents a novel fast-frequency pulsed tungsten inert gas (FFP-TIG) welding technology to fabricate a high-reliability Ti–6Al–4V weld. The effects of fast-frequency pulsed waveforms on microstructures and mechanical properties of Ti–6Al–4V weld samples were uncovered. The arc core diameter of FFP-TIG technology was reduced by 32%–36% compared with that of conventional TIG. The adoption of FFP-TIG decreased the average grain sizes and acicular martensite α′ within the Ti–6Al–4V weld by 47.7% and 40.5%, respectively, which further enhanced the mechanical properties of the corresponding weldments. The hardness, tensile strength, and elongation of Ti–6Al–4V weldments obtained by FFP-TIG were improved by 10.35%, 13.84%, and 304.61% compared with those obtained by conventional TIG, achieving the highest value of 373 HV, 1018.97 MPa, and 4.301%, respectively. This study provides fresh insight into the development and application of high-reliability titanium alloy weldments commonly used in the aviation industry.