Wire-arc directed energy deposition (DED) of Al–Zn–Mg–Cu alloy faced a tough challenge because the occurrence crack and pore defects caused by high content alloying elements. Three cold metal transfer (CMT) arc modes were studied to fabricate components via wire-arc DED process, with aim optimizing process revealing action mechanism mode on microstructure mechanical properties. The effect CMT forming accuracy arc/droplet behaviors was investigated assistance microscope high-speed camera....

The pore defects and grain coarsening are the main reasons for performance deterioration in wire-arc directed energy deposition (DED) of ultra-high-strength aluminium alloy. In this study, experimentation numerical simulation were performed to investigate Zn element loss, bubble behaviours, microstructure effects wire feeding rate (WFR) DED 7075 results suggested that both Zn-bubble H-bubble did not flow upward directly, but flowed with molten pool convection. A low WFR decreased sources...

Low-transformation-temperature (LTT) materials induce compressive residual stresses within an effective depth in wire arc additive manufacturing (WAAM), which is well suited for cladding applications. However, this role was found to be sensitive the phase transformation sequence. We developed LTT material—16Cr8Ni (16Cr8Ni-LTT)—and explore its potential, it clad onto a KA36 substrate via WAAM. Three different interpass temperature strategies were designed as follows: (1) no control; (2)...

A hybrid laser–GMAW-based directed energy deposition (DED) was developed to stabilise the cathode jet and droplet transfer in DED of Ti alloy. High-speed photography, spectroscopic diagnostic, theoretical calculation, numerical simulation were employed investigate stabilising mechanisms. At a high laser density, highest temperature molten pool located laser-irradiated zone, generating stable jet. atoms easily ionised into ions at temperatures (>8200 K); therefore, primarily composed ions....

Computational model of submerged arc welding (SAW) was developed to clarify the phenomena and heat source characteristics. Furthermore, weld part during SAW observed using an X-ray transmission system. To investigate effect closed space on phenomena, flux current density distributions a base metal surface gas tungsten were measured by split anode method. results showed that vapor concentration in became higher because generated space. However, its input almost same as welding. Meanwhile,...

Behaviors of flux, slag and molten metal during a submerged arc welding with large current were observed by the X-ray observation system including high speed video camera. Moreover, direct using camera was also carried out to observe phenomena, which could not be observation. From results, weld part classified broadly into 4 regions. Then, it clarified that pushed backward in direction when approached wire an plasma existed around. As result this series behaviors, preformed cavity filled at...

Tungsten electrode contamination caused by metal vapour from a base during tungsten inert gas welding was investigated. The ions transported the weld pool surface were deposited on welding. fraction of layer decreased because diffused inside electrode. melting point lowered, decreasing to operating temperature. Results show that melted and deformed. This promoted when larger amount surface.

In this study, the convective flow in a weld pool during GMA welding process was clarified by numerical simulation using an incompressible smoothed particle hydrodynamics method. The computational domain of two-dimensional vertical section base metal along direction system whose consumable electrode moved. revealed that molten droplet fell into and generated wave which travelled backward. When hit solid bead, it swelled up as solidified generating wavy surface, is observed actual welding....

The numerical model was developed using a SPH (Smoothed Particle Hydrodynamics) method and the projected transfer phenomena during GMA (Gas Metal Arc) welding were simulated by to clarify mechanisms of phenomena. As result, droplet mode obtained from this calculation regarded as in which liquid column grew about 1 mm up until its diameter became large same wire diameter, after that it detached tip column. In addition, 10 droplets formed for 0.1 s through these growth detachment processes at...

A molten metal droplet transfer processes were simulated by a numerical model using three-dimensional smoothed particle hydrodynamics method in order to clarify the flux column formation mechanism at tip of wire during cored arc welding process. This study focuses on with TiO2 based wire.As result, although average size obtained computation was larger than that experiment, length showed agreement which supports supported validity this computational model. Moreover, melting rate metal-pipe...

In this study, welding phenomena during submerged arc (SAW) were revealed with X-ray observation. the experiment, test coupon was placed between source and high-speed camera. The area surrounding observed from an angle perpendicular to direction vnat a frame rate is 3000 f s–1. From observation results, droplet transfer, weld pool molten flux (slag), which previously unknown, investigated. transfer mode spray transfer. With high polarity ratio comparable electrode negative (EN ratio),...

Droplet ejections from a molten tungsten electrode during alternating current inert gas (AC TIG) welding were observed successfully by high-speed video captured at 75,000 fps. The conditions and timings that likely to occur investigated. surface temperature was also measured. A crater formed on the of electrode, droplet ejection occurred following separation tip ridge growing centre crater. series time scale approximately 0.4 ms. Our results showed high common factor for ejections. dominant...

A drop transfer mode and a rotating in high current gas metal arc welding named buried were modeled using particle method that was suitable for numerical simulations of fluid behavior with phase changes large deformations. Numerical the space weld pool formation processes both condition conducted computational models to clarify effects pressure distribution transport position molten droplets on space. Finally, conditions combining these modes imitate low frequency modulated voltage control...

In this study, to clarify effects of the rare earth metal (REM) on arc phenomena, observations an appearance and a transfer during gas welding using REM added wire by high-speed camera were conducted. Moreover, temperature measurements plasma carried out monochromators cameras. As result, spray mode was observed with electrode negative polarity when shielding including CO2 used. The globular obtained 100%Ar used as gas. These results showed reverse tendency compared conventional positive...

Electron density distribution during an alternative current gas tungsten arc generated under Mars-like atmosphere in a vacuum chamber was measured to clarify characteristics atmosphere. The electron by Abel inversion processing and infrared method for plasma diagnostic, which obtained the spectral radiance of arc. Measured results showed that electrode negative period spreader than on Earth. Moreover, its peak value about 2.5×1022 m-3, almost one order lower result

Simulation of molten flux flow during submerged arc welding was carried out by a hybrid method using Discrete Element Method and Incompressible Smoothed Particle Hydrodynamics method. As result, melting process calculated with time evolution. Moreover, it also simulated that re-solidified at backward heat source. In this simulation, the average thickness slag z = 5.0±0.25 mm (the center wire in direction) estimated to be 4.8 mm. These results showed potential usefulness simulate SAW.