Influence of current pulsing on microstructure and mechanical properties of Ti–6Al–4V TIG weldments

Abstract

The present study has investigated the influence of current pulsing on the structure and mechanical properties of Ti-6Al-4V tungsten inert gas (TIG) weldments. Autogenous full penetration bead on plate TIG welds were made with and without direct current pulsing. Microstructural observations and evaluation of hardness, tensile and fatigue properties of the weldments were made in different conditions: as welded and post-weld heat treatment (PWHT) conditions (PWHT was done at 700 and 900uC). Current pulsing resulted in slight refinement of prior b grains, leading to better tensile strength, ductility and fatigue lives of weldments in the as welded condition. In the case of weldments subjected to PWHTs, the pulsed weldments exhibited inferior fatigue lives compared with the unpulsed weldments. The PWHT done at 900uC resulted in inferior fatigue lives of weldments compared with that done at 700uC.

Establishing relationship between fusion zone hardness and grain size of gas tungsten constricted arc welded thin sheets of titanium alloy

“…Figure 7 shows BM optical micrograph (OM) and scanning electron micrographs (SEM) and FZ of the joints fabricated with the optimized parameter (I M = 50 A, I P = 30 A, I F = 12 kHz and S = 60 mm/min). The formation of finer grains as well as acicular alpha (α′) martensite in fusion zone is main reasons for higher hardness and minimum fusion zone grain size in these joints [7,8].…”

“…It can be strengthened by various heat treatment and strain hardening processes, in particular by solutionizing with subsequent quenching [4][5][6]. Moreover, this alloy is very sensitive to thermal cycles during welding, results in catastrophic variations in the microstructure [7,8]. Electron beam welding (EBW) and laser beam welding (LBW) are considered as a perfect joining technique for Ti-6Al-4V alloys due to the specific advantages such as high depth of penetration, lesser welding defects and narrower HAZ and FZ compared to GTAW [9][10][11][12].…”

Proposta de roteiro para a determinação das variáveis de soldagem do Processo TIG pulsado aplicado à soldagem de chapas finas

“…As vantagens relatadas para este método incluem o maior controle sobre as características dimensionais do cordão de solda [8,9], maior tolerância às variações na dissipação de calor [10], menor aporte de calor [6,11,12], redução de tensões residuais e distorções da peça [11,13] e maior controle sobre a poça de fusão [7], princi-palmente em posições de soldagem desfavoráveis. Já do ponto de vista metalúrgico, as vantagens relatadas referem-se ao refino de grãos obtido na zona fundida [14], redução da largura da ZAC [15] e controle de segregação [16].…”

An Overview of TIG Welding of Ti6Al4V: Recent Developments

“…The choice of this alloy over other types of alloys have been predominately due to some unique properties it possesses, some of these properties are low distortion rate during welding, fly-to-weight ratio, low corrosion rate, high meting point etc. [11][12][13][14][15][16][17][18].…”