The influence of shielding gas (argon, helium) on the cathode spot (CS) behaviours in aluminium AC TIG welding was investigated by the high-speed (500,000 fps) observation. Moreover, the temperature of the weld pool surface was measured by the two-wavelength pyrometer method to discuss its relationship with the CS. Consequently, the average current per CS in the helium case was 16.7 A, higher than 7.6 A in the argon case. The larger current per spot is considered to cause the higher velocity of the CS on liquid surface in the helium case (168 ± 41 m s−1) than that in the argon case. The average number of the CS was almost zero within around a radius of 2.0 mm in helium, which had the temperature above 1300 K.
JenneyCL, O'BrienA.Welding handbook. Miami: American Welding Society; 2015.
2.
MurphyAB.A perspective on arc welding research: the importance of the arc, unresolved questions and future directions. Plasma Chem Plasma Process. 2015; 35:471–489. doi: 10.1007/s11090-015-9620-2
3.
TanakaM, TashiroS, SatohT.Influence of shielding gas composition on arc properties in TIG welding. Sci Technol Weld Join. 2008; 13:225–231. doi: 10.1179/174329308X283929
4.
UshioM, NakataK, TanakaM, Observations of cathode spot welding of aluminum alloy. Trans JWRI. 1994; 23:169–174.
5.
SarrafiR, KovacevicR.Cathodic cleaning of oxides from aluminum surface by variable-polarity arc. Weld J. 2010; 89:1–10.
6.
TashiroS, SawatoH, TanakaM.Experimental observation of cleaning action of cathode spots in AC TIG welding of aluminum plates. Jpn Weld Soc. 2011; 29:5s–8s. doi: 10.2207/qjjws.29.5s
7.
YujiT, TashiroS, FujimaruA, Observation of the behavior of cathode spots in AC tungsten inert gas welding on aluminum plate. Q J Jpn Weld Soc. 2015; 33:135s–138s. doi: 10.2207/qjjws.33.135s
8.
PhanLH, TashiroS, VanBH, Investigating cathode spot behavior in argon alternating current tungsten inert gas welding of aluminum through experimental observation. J Phys D Appl Phys. 2019; 52:26LT02. doi: 10.1088/1361-6463/ab198a
9.
TanakaM, LowkeJJ.Predictions of weld pool profiles using plasma physics. J Phys D Appl Phys. 2007; 40:R1–R23. doi: 10.1088/0022-3727/40/1/R01
10.
AndersA.Cathodic arcs: from fractal spots to energetic condensation. New York: Springer; 2008.
11.
GoldsmithS, BoxmanRL.Excited-state densities in a multicathode-spot Al vacuum arc. I. Spectroscopic measurements. J Appl Phys. 1980; 51:3649–3656. doi: 10.1063/1.328146
12.
YokomizuY, MatsumuraT, SunWY, Electrode sheath voltages for helium arcs between non-thermionic electrodes of iron, copper and titanium. J Phys D Appl Phys. 1998; 31:880–883. doi: 10.1088/0022-3727/31/7/017
13.
ZöhrerS, AndersA, FranzR.Influence of Ar gas pressure on ion energy and charge state distributions in pulsed cathodic arc plasmas from Nb–Al cathodes studied with high time resolution. J Phys D Appl Phys. 2019; 52:055201. doi: 10.1088/1361-6463/aaeecc
14.
KaufmannHTC, CunhaMD, BenilovMS, Detailed numerical simulation of cathode spots in vacuum arcs: interplay of different mechanisms and ejection of droplets. J Appl Phys. 2017; 122:163303-1–163303-14. doi: 10.1063/1.4995368
15.
MesyatsGA, UimanovIV.Hydrodynamics of the molten metal during the crater formation on the cathode surface in a vacuum arc. IEEE Trans Plasma Sci. 2015; 43:2241–2246. doi: 10.1109/TPS.2015.2431317
16.
AlmeidaNA, BenilovMS, BenilovaLG, Near-cathode plasma layer on CuCr contacts of vacuum arcs. IEEE Trans Plasma Sci. 2013; 41:1938–1949. doi: 10.1109/TPS.2013.2260832
17.
ShoichiM, YukioM, KokiT, Study on the application for electromagnetic controlled molten pool welding process in overhead and flat position welding. Sci Technol Weld Join. 2013; 18:38–44. doi: 10.1179/1362171812Y.0000000070
