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Advanced studies and developments of the E.O. Paton electric welding institute in welding and allied technologies

Paton Boris E.

Biuletyn Instytutu Spawalnictwa w Gliwicach

2019

Vol. 63, No. 1

7--18

Omówiono szereg nowych rozwiązań Instytutu Spawania Elektrycznego, które zostały opracowane w ciągu ostatnich lat, w tym technologie i urządzenia do spawania z zastosowaniem wysokoskoncentrowanych źródeł energii – plazmowego, laserowego oraz wiązki elektronów. Opracowano technologie spawania: rur, tytanu o dużej grubości, stopów aluminiowo-litowych i stali o podwyższonej wytrzymałości, a także technologie parowo-gazowe służące do produkcji nanostrukturalnych materiałów do łączenia materiałów kompozytowych oraz międzymetalicznych. Opracowano również technologie i urządzenia do spawania i cięcia pod wodą, nowe narzędzia do spawania wiązką elektronów w otwartej przestrzeni kosmicznej. W celu zwiększenia trwałości i niezawodności spoin zaproponowano wykorzystanie po spawaniu obróbki z zastosowaniem impulsów prądu elektrycznego o dużej gęstości oraz przekuwanie mechaniczne o wysokiej częstotliwości. W zakresie badań nieniszczących opracowano urządzenia numeryczne na bazie przetworników mikroprocesorowych, a dla wyrobów o skomplikowanym kształcie – robot przemysłowy wyposażony w układ śledzenia. Opracowano nowy sposób hodowania monokryształów metali trudnotopliwych. Opisano nowe urządzenia i narzędzia do zgrzewania tkanek żywych.

The article presents a number of recent solutions developed at the E.O. Paton Electric Welding Institute including technologies and equipment for welding performed using highly-concentrated power sources such as plasma, laser and the electron beam. The above-named technologies were developed in order to weld pipes, thick titanium, aluminium–lithium alloys and high-strength steels. The solutions presented in the article also include vapour-phase technologies used in the production of nanostructured materials enabling the joining of composite materials and intermetallics. The article also discusses newly developed technologies and equipment used in underwater welding and cutting as well as a new electron beam tool for welding in outer space. In addition, the article suggests the application of postweld treatment based on high-density electric impulses and high-frequency mechanical peening in order to increase the service life and reliability of welds. In addition, the article presents the use of digital equipment based on high-sensitive solid-body converters used in non-destructive tests of welded joints as well as the application of industrial robots provided with a technical vision system in relation to products characterised by complex geometry. The article also presents a new method enabling the growing of single crystals of refractory metals and new equipment enabling the welding of live tissues.

Characterizing the brittle fracture and the ductile to brittle to ductile transition of heat-treated binary aluminum-lithium alloys

Fragomeni J. M.

Engineering Transactions

2001

Vol.49, iss.4

573-598

An aluminum alloy containing 2.6wt.% Li and 0.09wt.% Zr exhibited a very low value in tensile ductility consistently prior to the peakaged strength independent of thermal treatment. A transition was characterized by very low ductility in the slightly underaged condition up to the near peakaged condition, then followed by a substantial increase in ductility with aging after the peakaged treatment. In order to better understand the deformation and fracture, a scanning electron microscopy study of the fracture surfaces of Al-2.6wt.% Li-0.09wt.% Zr tensile samples solution heat-treated and artificially aged was performed to relate the mechanical behavior to microstructure in the precipitation hardened Al-Li alloy. SEM analysis of the surface features and fracture morphology of the alloy was performed to understand the mechanisms of fracture in relation to the ductile-to-brittle transition that resulted in the alloy from precipitation hardening. TEM analysis was also performed to characterize the deformation behavior, and revealed the distribution of precipitates (both Al3Li (a') and Al3Zr-Al3Li) in the microstructure at very high magnifications as well as the dislocation subgrain structure of the alloy at lower magnification. It follows from this study that the presence of a' particles in the matrix promotes intense planar slip which was believed to be responsible for the ultra-low ductility prior to the peakaged temper. Based on a detailed quantitative microscopy study, it was proposed that the increase in the ductility of the alloy after aging was a consequence of particle coarsening with aging and thus resulting in the Orowan process due to the transition from dislocation particle shearing to dislocation particle bypassing.