Joining of Dissimilar AZ31B Magnesium Alloy and SS400 Mild Steel by Hybrid Gas Tungsten Arc Friction Stir Welding

주성민 대한금속·재료학회 2013 METALS AND MATERIALS International Vol.19 No.6

The joining of dissimilar materials, magnesium alloy (AZ31B) and mild steel (SS400), was performed using a hybrid gas tungsten arc-friction stir welding (HGTAFSW) method that applied a preceding gas tungsten arc welding (GTAW) preheating heat source to a mild steel plate surface during friction stir welding (FSW). The mechanical and microstructural characteristics of the HGTAFS welds were evaluated and compared to those of FS welds to confirm the effect of the additional GTAW preheating heat source. The tensile strength of the HGTAFS welds was approximately 91% of that of the magnesium alloy base metal but higher than that of the FS welds. This was attributed to the enhanced material plastic flow and partial annealing effect in the magnesium alloy and mild steel materials by GTAW reheating of the mild steel side, which induced a significant increase in the elongation of the welds. The concentration profiles indicated that no intermetallic FeAl and FeAl3 compounds had formed according to the phase diagram, which led to a decrease in joint strength. Overall, the use of HGTAFSW by applying a GTAW preheating heat source to a mild steelplate surface resulted in a mechanically sounder and metallurgically defect-free welds compared to FSW.

GTA용접용 텅스텐 전극팁의 형상과 연마 상태가 아크특성에 미치는 영향

조상명,서상균 대한용접접합학회 2001 대한용접·접합학회지 Vol.19 No.1

The welding quality by Gas Tungsten Arc Welding shows very high level, but the welding speed is lower than that of gas metal arc welding. Also, the welding quality by automatic GTAW is variable as the arc characteristics is changed by the consumption of electrode tip. The purpose of this study is to investigate the relation between the properties of tungsten electrode tip and the various arc characteristics at high current region. In this study, the high welding current 200A was applied to the repeated arc start test and long term arcing test using the $\phi$3.2 tungsten electrodes with cone angle 30$^{\circ}$, 45$^{\circ}$, 60$^{\circ}$sharp tip, and 60$^{\circ}$surface polished (S.P.) sharp tip. It was confirmed that the maximum arc pressure by the initial electrode condition was highest in 45$^{\circ}$sharp tip, and the next in 60$^{\circ}$sharp tip, the last was in 30$^{\circ}$sharp tip and 60$^{\circ}$S.P.. But, the maximum arc pressure after the repeated arc start test and long term arcing test was decreased considerably. But, the maximum arc pressure was highest also in 45$^{\circ}$ sharp tip after the tests, the next was in 30$^{\circ}$sharp tip, and the last was in 60$^{\circ}$sharp tip and 60$^{\circ}$S.P.. The arc start characteristics was the most excellent in 60$^{\circ}$S.P., By long term arcing test, the lanthania included in tungsten electrode was extinguished at tip surface preferentially, therefore the arc characteristics of electrode tip got worse.

펄스 TIG용접에서 필러 와이어 송급속도에 따른 아크압력 변동이 용입에 미치는 영향

조상명,김진우 대한용접접합학회 2004 대한용접·접합학회지 Vol.22 No.1

In the standpoint of the arc pressure, the effects of the filler wire feed rate on the penetration was investigated in this study. The pure Ar gas was used as a shield gas and the parameters investigated were the welding current and the filler wire feed rate. By making the experiment on the arc pressure, we could know that the arc pressure was fluctuated as the depth-into-arc of the tungsten rod. Instead of the filler wire, the tungsten rod was supplied into the molten pool to make this experiment. Because the filler wire melted in arc and then we couldn't measure the arc pressure. So, the tungsten rod - the highest melting point - was used. According to the depth-into-arc of the tungsten rod, the arc pressure could be measured by using the manometer. It was proved that the arc pressure got higher as the wire feed rate was slow. It is reported the arc pressure is proportion to welding voltage and the square of welding current. But, in the filler wire TIG welding, we could blow that arc pressure was fluctuated as the depth-into-arc of filler wire was changed. We could measure the arc pressure by the variation of the filler wire feed rate and could verify that it affected bead shape and penetration.

용접방법에 의한 타이타늄 연결부의 기계적 성질에 관한 연구

이수영,장익태,허성주,임순호,Lee, Soo-Young,Chang, Ik-Tae,Heo, Seong-Joo,Yim, Soon-Ho 대한치과보철학회 1999 대한치과보철학회지 Vol.37 No.5

The use of pure titanium and titanium alloys have been increased recently in fixed, removable prosthodontics and implant fields as a framework. But when they were used for superstructures of implant or metal framework of removable prosthesis, welding is necessary to reconnect the fracture site to control the casting distortions. To overcome the difficulties in soldering the titanium due to high oxidation property, much effort have been devoted. In this study, some of mechanical properties were compared between pure titanium and Ti-6Al-4V alloy by using after welding, electron beam welding technique and tungsten arc welding. Mechanical properties such as tensile strength, yield strength, elongation and microhardness were measured. And, in order to compare the effect of welding site and surrounding metal tissue according to the welding condition, SEM photographs were taken and element distribution was observed by Wave Dispersion Spectroscopy. Through analyses of the data, following results were obtained; 1. In items such as tensile strength, yield strength and elongation according to the welding techniques of pure titanium, only tungsten arc welded group showed significant lower value than other groups(P<0.05). 2. In items such as tensile strength and yield strength according to the welding techniques of Ti-6Al-4V alloy, control group and tungsten arc welded group showed significant difference among all the groups(P<0.05). 3. Ti-6Al-4V alloy exhibited significantly greater elongation than control group when the laser welding method and electron beam welding method were used, and elongation showed increasing tendency. 4. Pure titanium specimens exhibited increasing tendency of microhardness regardless of the weld-ing technique applied, and especially tungsten arc welded group demonstrated a great increase of microhardness than parent metal. 5. There was no hardness change in laser welded group and electron beam welded group of Ti-6Al-4V alloy, but in tungsten arc welded group, hardness changed greatly from parent metal to weld seam. 6. Through the metallographic examination and scanning electron microscopy, laser welding caused central fusion and recristallizations were formed and tungsten arc welding caused localized fusion to 0.3-0.7mm from the surface.

Development of Tungsten Electrode for TIG Welding

이희근,윤광희,강정윤 대한용접·접합학회 2022 대한용접·접합학회지 Vol.40 No.4

Tungsten Inert Gas (TIG) welding process is mostly applied to high alloy steel pipes including stainless steels be- cause of superior welding quality and gap bridge-ability than other welding processes. However, it has poor pro- ductivity due to low welding speed and deposition rate. In order to improve TIG welding productivity, high perform- ance TIG welding with higher arc temperature, automation and high deposition rate system including hot wire have been developed. Higher arc temperature and longer welding time damage tungsten electrodes of TIG welding. It causes welding defect such as tungsten inclusion and short replacement cycle of tungsten electrodes. Various types of tungsten electrodes containing rare earth metal oxides (thorium, lanthanum, cerium, etc) were introduced to im- prove electrode erosion resistance and arc stability. In this study, their operation characteristics, arc starting perform- ance, tip development, and electrode consumption were reviewed.

Effects of Tungsten Particle Size and Nickel Addition in DC arc Resistance of Cu-W Electrode

Kim, Bong-Seo,Jeong, Hyun-Uk,Lee, Hee-Woong The Korean Institute of Electrical Engineers 2004 KIEE International Transactions on Electrophysics Vol.4C No.2

The performance of copper-tungsten for electrodes used in an ultra high voltage interruption system was evaluated by means of an interruption test, which requires a large-scale apparatus and high cost. In this study, prior to the interruption test, the characteristics of a Cu-W electrode were estimated through the DC arc test, which is a simple, low cost procedure. The DC arc characteristics of a 20wt%Cu-80wt%W electrode were investigated with the change of tungsten powder size distribution and the addition of nickel. In specimens containing a high volume fraction of large sized tungsten particles, the relative density and hardness of sintered Cu-W electrodes increased while the electrical conductivity and the DC arc resistance decreased. Furthermore, the relative density became enhanced with the increase of the amount of nickel while the hardness and electrical conductivity diminished and the DC arc resistance worsened.

아크용접에서 극성이 비드형상에 미치는 영향에 관한 연구

박정길,이종수,이보영 한국 항공대학교 항공산업기술연구소 1999 航空宇宙産業技術硏究所 硏究誌 Vol.9 No.-

소모성 용접봉(FCAW, GMAW 및 SAW)을 사용하는 용접에 대해서 극성의 영향이 실험적으로 연구되었다. CO₂를 보호가스로 이용하였고, 다른 용접변수를 일정하게 유지하고 극성을 변화시켜가며 실험을 실시하였다. 실험결과 FCAW에서는 극성에 따라 비드형상에 거의 차이를 보이지 않았다. 하지만, GMAW 및 SAW에서는 역극성에서 용입이 깊은 걸로 확인되었다. 따라서 정극성에서 용입이 깊은 GTAW와는 반대의 결과를 확인할 수 있었다. The effect of polarity was studied experimentally in consumable electrode arc welding, such as FCAW(Flux Cored Arc Welding), GMAW(Gas Metal Arc Welding), and SAW(Submerged Arc Welding). The experiment was carried out using CO₂shielding gas in which other welding parameters except polarity were kept constant. According to the results of this experiment, there was no difference in bead geometry in FCAW, but we could get deeper penetration in reverse polarity than in straight polarity in GMAW & SAW. Accordingly, the results of this experiment was opposite to that of GTAW.

Micro-scale gas tungsten arc welding on invar sheet

Im Jaeseung,정진영,Choi Soobong,Lee Ki Hoon,Seo Jeong-Hyun 한국물리학회 2024 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.85 No.4

Manipulation of metal microstructures via welding technique has attracted many interests due to its various applications for microscopic electronic circuits and photo-electronic structures. Reflling deletion of structures is challenging in sculpting metal microstructure. We propose the micro-size gas tungsten arc welding (GTAW) technique to overcome these challenges. The welded area of ~10 s μm are achieved by using an etched 100 μm W wire with optimized arc current and voltage control. The spatial size and depth of the welded spot in the invar surface show dependency on the arc current and voltages under proper Ar gas fow. We believe that these results can provide technical intuition for developing many industrial applications.

Effects of Laser and Tungsten Arc Welding Processes on the Thermal Softening and Mechanical Properties of Almag6 Aluminum Alloy

Yeonho Kwak,Tae Hoon Kang,Seung Hwan Lee,Minjung Kang 한국정밀공학회 2023 International Journal of Precision Engineering and Vol.24 No.4

The adoption of aluminum in the mobile industry is driving development of aluminum alloys. Among the additive elements of aluminum alloy, magnesium is a crucial component commonly included in various commercial aluminum alloys. Because of its ability to enhance solid solution strengthening and work hardening, many researchers are investigating methods to increase the magnesium content in aluminum applications. Almag6 contains more than 6 wt% of magnesium and exhibits excellent structural properties; it possesses higher yield and tensile strengths than the commercial 5XXX series of aluminum materials. However, work-hardening alloys are vulnerable to welding heat. In this study, laser and tungsten arc welding processes were performed to study the effect of welding heat on the mechanical and microstructure properties of Almag6. It was found that the mechanical strength and hardness of the welds reduced significantly. Similar to other work-hardening aluminum alloys, the lowest hardness was measured in the fusion zone with a strength of over 200 MPa. Relatively low breaking strengths were measured in the tungsten arc welding specimens owing to grain coarsening in the welds.

Spot-GTA 용접자세에 따른 304 스테인리스강 용융지 표면 및 용접부 형상 거동

Kang, Nam-Hyun,Park, Yeong-Do,Cho, Kyung-Mox,Singh, Jogender,Kulkarni, Anil 대한용접접합학회 2008 대한용접·접합학회지 Vol.26 No.2

Effects of gravitational orientation on gas tungsten arc welding (GTAW) for 304 stainless steel were studied to determine the critical factors for weld pool formation, such as weld surface deformation and weld pool shape. This study was accomplished through an analytical study of weld pool stability as a function of primary welding parameters (arc current and arc holding time), material properties (surface tension and density), and melting efficiency (cross-sectional area). The stability of weld pool shape and weld surface deformation was confirmed experimentally by changing the welding position. The arc current and translational velocity were the major factors in determining the weld pool stability as a function of the gravitational orientation. A 200A spot GTAW showed a significant variation of the weld pool formation as the arc held longer than 3 seconds, however the weld pool shape and surface morphology for a 165A spot GTAW were 'stable', i.e., constant regardless of the gravitational orientation. The cross-sectional area of the weld (CSA) was one of the critical factors in determining the weld pool stability. The measured CSA ($13.5mm^2$) for the 200A spot GTAW showed a good agreement with the calculated CSA ($14.9mm^2$).