Welding Metallurgy of
01 Jan 1987-
About: The article was published on 1987-01-01 and is currently open access. It has received 991 citations till now. The article focuses on the topics: Welding.
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01 Apr 2019
TL;DR: In this paper, an attempt has been made to design and develop an intermediate electrode based on CaO-CaF2-SiO2 ternary phase diagram system and nickel as an additional electrode coating ingred...
Abstract: The bimetallic welds between ferritic low alloy steels and austenitic stainless steels are widely used in the heat piping transport systems of nuclear power plants for connecting the heavy section low alloy steel components with those of high temperature stainless steel pipes. The operating experience of major nuclear power plant components has recently shown that bimetallic joints can jeopardize the plant availability and safety because of increased incidences of failure. In shielded metal arc welding process, the occurrence and severity of weld defects mainly depend upon the type of electrode filler wire and the electrode coating ingredients used. The use of nickel based filler metals is no longer considered as the final solution for unexpected failures of bimetallic welds due to incidences of hot cracking. In the present paper, an attempt has been made to design and develop an intermediate electrode based on CaO–CaF2–SiO2 ternary phase diagram system and nickel as an additional electrode coating ingred...
23 citations
Cites background from "Welding Metallurgy of"
...This could be explained from the fact that Si4þ metallic cation from slag is reduced and increases the silicon content in the weld pool–slag interface during electrode positive polarity.(21) The accompanying reaction is shown:...
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TL;DR: In this paper, the weld nugget formation in three-sheet aluminum alloy resistance spot welding was investigated and three failure modes were identified, namely interfacial, mixed, and pullout.
Abstract: This paper investigates the weld nugget formation in three-sheet aluminum alloy resistance spot welding. The nugget formation process in three equal thickness sheets and three unequal thickness sheets of 5052 aluminum alloy were studied. The results showed that the nugget was initially formed at the workpiece/workpiece interfaces (i.e., both upper interface and lower interface). The two small nuggets then grew along the radial direction and axial direction (welding direction) as the welding time increased. Eventually, the two nuggets fused into one large nugget. During the welding process, the Peltier effect between the Cu-Al caused the shift of the nugget in the welding direction. In addition, the mechanical strength and fracture mode of the weld nuggets at the upper and lower interfaces were also studied using tensile shear specimen configuration. Three failure modes were identified, namely interfacial, mixed, and pullout. The critical welding time and critical nugget diameter corresponding to the transitions of these modes were investigated. Finally, an empirical failure load formula for three-sheet weld similar to two-sheet spot weld was developed.
23 citations
TL;DR: In this paper, the effect of grain structure on the mechanical properties and in vitro corrosion behavior of pure Zn samples, by varying the scanning speed and building direction during the laser powder bed fusion (LPBF) process, was investigated.
Abstract: Laser powder bed fusion (LPBF) has been previously used to produce customized medical implants from biodegradable Zn and its alloys. In this study, we investigated the effect of the grain structure on the mechanical properties and in vitro corrosion behavior of pure Zn samples, by varying the scanning speed and building direction during the LPBF process. Increasing the scanning speed from 300 to 700 mm/s resulted in finer grains, irregular grain morphology, and a weaker grain texture, which enhanced the strength and ductility. Vertically built LPBF Zn tensile samples had higher strength and ductility compared with horizontally built samples, indicating strong anisotropy of the mechanical properties. Electrochemical tests revealed that the in vitro corrosion behavior was not strongly correlated with the scanning speed. This was attributable to the random distribution of tiny pores on the surface of the LPBF samples, although immersion tests showed that the sample prepared with the highest scanning speed exhibited the highest corrosion rate. With increasing immersion time in Hank’s solution, the Zn2+ concentrations of the samples produced with different scanning speeds increased, their pH stabilized, and the differences between the corrosion rates narrowed. The effects of the processing parameters on the final performance of the samples could be well explained by the grain structures. The findings of this study afford bases for selecting the processing parameters for optimizing the properties of LPBF-produced Zn parts for biodegradable applications.
23 citations
Cites background from "Welding Metallurgy of"
...The recoil force of the evaporation results in a slender cavity, commonly referred to as a keyhole in laser welding, when the laser energy density is over 10(6)W/cm(2) [35]....
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...center, along location dependent directions, resulting in a centripetal distribution around the melt pool, where the epitaxial growth is attributed to the temperature gradient [35]....
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TL;DR: In this paper, a single alloy was arc welded with seven different filler metals, including Cu, Cu 12Ni, Cu 22 Ni, Cu 30 Ni and Ni, and the liquidus temperatures of the base metal T LB and the bulk weld metal T LW were compared.
Abstract: More often than not, filler metals differ from the workpiece in composition. To study macrosegregation in a single alloy system, alloy Cu–30Ni was arc welded with seven different filler metals, including Cu, Cu–12Ni, Cu–22Ni, Cu–30Ni, Cu–45Ni, Cu–67Ni and Ni. It was explained that liquid 1 flowing into liquid 2 of a different composition can cause macrosegregation if liquid 2 is below the liquidus temperature of liquid 1 to make liquid 1 freeze quickly. The liquidus temperatures of the base metal T LB and the bulk weld metal T LW were compared. All four mechanisms proposed recently by the authors were identified: mechanisms I (T LW T LB and quick freezing along pool boundary), III (T LW T LB and quick freezing near pool bottom).
23 citations
TL;DR: In this paper, traditional spot weld and magnetically assisted spot welds were made in 225mm thick galvanized dual-phase steel, and the weld microstructures were compared.
Abstract: Traditional spot welds and magnetically assisted spot welds were made in 225 mm thick galvanised dual-phase steel, and the weld microstructures were compared The magnetically assisted weld nugget
23 citations
References
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TL;DR: In this article, the state of the art in selective laser sintering/melting (SLS/SLM) processing of aluminium powders is reviewed from different perspectives, including powder metallurgy (P/M), pulsed electric current (PECS), and laser welding of aluminium alloys.
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TL;DR: In this article, the authors show that the pre-existing dislocation network, which maintains its configuration during the entire plastic deformation, is an ideal modulator that is able to slow down but not entirely block the dislocation motion.
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TL;DR: In this article, the fundamental understanding of structure-properties relationship in automotive steels resistance spot welds is discussed. And a brief review of friction stir spot welding, as an alternative to RSW, is also included.
Abstract: Spot welding, particularly resistance spot welding (RSW), is a critical joining process in automotive industry. The development of advanced high strength steels for applications in automotive industry is accompanied with a challenge to better understand the physical and mechanical metallurgy of these materials during RSW. The present paper critically reviews the fundamental understanding of structure–properties relationship in automotive steels resistance spot welds. The focus is on the metallurgical characteristics, hardness–microstructure correlation, interfacial to pullout failure mode transition and mechanical performance of steel resistance spot welds under quasi-static, fatigue and impact loading conditions. A brief review of friction stir spot welding, as an alternative to RSW, is also included.
369 citations
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