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1
Content available The effect of the coating process thermal cycle on mechanical properties of AA6061-T6 used for load-carrying elements of a space instrument: a case study
Barciński Tomasz, Kosturek Robert, Kowalski Tomasz, Bzowski Maciej, Wawrzaszek Roman, Mostowy Karol, Baran Jędrzej, Daukszo Maciej
Bulletin of the Polish Academy of Sciences. Technical Sciences
|
2024
|
Vol. 72, nr 5
art. no. e150338
EN
Components used for the structure of the GLObal Solar Wind Structure experiment in the NASA Interstellar Mapping and Acceleration Probe space mission, made of AA6061-T6 alloy, are subjected to the coating process, where the temperature affects its mechanical properties. This paper aims to examine the impact of the coating thermal cycle on the mechanical properties of AA6061-T6 alloy, which is the load-carrying material in a spaceborne instrument. As a part of the manufacturing process, the parts made of AA6061-T6 are subjected to a coating process at a temperature of about 220◦C for a time longer than 1 hour. This treatment modifies the mechanical properties of the alloy. To evaluate the consequences of this change for spaceborne components, mechanical testing, and numerical simulation were conducted. It was found that as a result of the coating process, the reduction in AA6061-T6 yield strength is about 16%, which entails a decrease in the margins of safety by 25% at its maximum.
2
Content available remote Structural integrity of AA7075-T651 UWFSW joints
Kosturek Robert, Ślęzak Tomasz, Torzewski Janusz
Advances in Materials Science
|
2024
|
Vol. 24, nr 4(82)
98--110
EN
This investigation is focused on the comparison of selected low-cycle fatigue properties of AA7075-T651 friction stir welded and underwater friction stir welded joints together with the evaluation of their lifetime prediction by the Manson-Coffin-Basquin formula. Additionally, the analysis of the fractured surface was involved to describe the character of joints decohesion. The analysis of the obtained hysteresis loops revealed that FSW joint exhibits cyclic hardening, with a stable maximum stress and a decreasing minimum stress, leading to an increased contribution of compressive stresses and a lower mean stress during stabilized fatigue. In comparison, the UWFSW joint also shows cyclic hardening but with a greater contribution of tensile stresses, a higher mean stress, and a reduced participation of plastic deformation. The Manson-Coffin-Basquin equation effectively predicts the fatigue life of AA7075-T651 alloy joints, with UWFSW joints showing significantly lower standard deviation (0.0035 vs. 0.0135) and narrower dispersion bands (1.61 vs. 1.93) compared to conventional FSW joints.
3
Content available Studies of the microstructure of bimetallic titanium – austenitic steel joints obtained by explosive welding
Wachowski Marcin, Kosturek Robert
Materiały Wysokoenergetyczne
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2023
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T. 15
15--23
EN
The specific requirements of installations used in the chemical and petrochemical industries require materials with high corrosion resistance and adequate strength. Materials with these characteristics can be obtained by explosive cladding technology. Results of studies of the microstructure of titanium-austenitic steel 304L bimetallic joints in the welded and heat-treated condition are presented. Applications for this type of material include heat exchanger tube surfaces exposed to aggressive environments with high cyclical mechanical loads. The joints were tested using an optical microscope and a scanning electron microscopy. Heat treatment has contributed to a decrease in microhardness near the joint, which demonstrates a reduction in the strain hardening in this area.
PL
Szczególne wymagania instalacji stosowanych w przemyśle chemicznym i petrochemicznym powodują konieczność stosowania materiałów o dużej odporności korozyjnej oraz odpowiedniej wytrzymałości. Materiały spełniające te wymagania można wytworzyć technologią platerowania wybuchowego. W pracy przedstawiono wyniki badań mikrostruktury złączy bimetalicznych tytan-stal austenityczna 304L w stanie po zgrzewaniu i po obróbce cieplnej. Aplikacją tego typu materiałów są m.in. ściany sitowe wymienników ciepła, które narażone są na pracę w agresywnym środowisku, przy wysokich cyklicznych obciążeniach mechanicznych. Złącza badano z wykorzystaniem mikroskopu świetlnego oraz skaningowej mikroskopii elektronowej. Obróbka cieplna przyczyniła się do spadku mikrotwardości w pobliżu złącza, co świadczy o redukcji strefy umocnienia występującej w tym obszarze.
4
Content available Research on the post-weld explosive hardening of AA7075-T651 friction stir welded butt joints
Kosturek Robert, Lewczuk Rafał, Torzewski Janusz, Wachowski Marcin, Słabik Piotr, Maranda Andrzej
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2023
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Vol. 71, nr 4
art. no. e145685
EN
In this paper, the post-weld explosive hardening of a 5 mm AA7075-T651 plate welded via FSW was performed. To investigate the possibility of increasing FSW joint mechanical properties, the welded plate was explosively treated with four various explosive materials (ammonal, emulsion explosive, FOX-7, and PBX) in two different hardening systems. As part of the investigation, the observations of the surface and macrostructure of the treated plates were described. The obtained microhardness distribution allowed us to register the increase in hardness of the SZ up to 6%, but no increase in hardness of the LHZ was reported. In most cases, the influence of explosive treatment on the mechanical properties of the welded joint was disadvantageous as ultimate tensile strength and ductility were reduced. The only positive effect which was observed is the increase in the value of yield strength up to 27% corresponding to 77 MPa, achieved by explosive materials with detonation velocity below 3000 m/s.
5
Content available remote Zastosowanie zgrzewania tarciowego z przemieszaniem (FSW) do wykonywania połączeń doczołowych wysokowytrzymałych stopów aluminium stosowanych w przemyśle zbrojeniowym
Kosturek Robert
Stal, Metale & Nowe Technologie
|
2022
|
nr 9-10
38--41
PL
Otrzymywanie wysokiej jakości połączeń spójnościowych umacnianych wydzieleniowo stopów aluminium stanowi jedną z decydujących batalii na froncie rozwoju współczesnej techniki, będąc istotnym motorem postępu przemysłu motoryzacyjnego, lotniczego i zbrojeniowego.
EN
This paper presents selected results of research concerning AA2519-T62 and AA7075-T651 butt joints produced with the FSW technique, including macroscopic observations, microhardness distributions and tensile tests. The applied welding technique enabled obtaining high-quality welds of the 87% and 77% joint efficiencies for AA2519-T62 and AA7075- -T651 respectively.
6
Content available Research on the Microstructure of Laser Beam Welded Sc-Modified AA2519-F Extrusion
Kosturek Robert, Śnieżek Lucjan, Grzelak Krzysztof, Wachowski Marcin
Archives of Metallurgy and Materials
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2022
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Vol. 67, iss. 2
773--778
EN
In this paper, the microstructure of laser beam welded Sc-modified AA2519-F has been taken under investigation. The welded joint has been produced using Fanuc 710i industrial robot equipped with YLS-6000 6 kW laser beam source. The welding speed and laser power were equal to 0.75 m/min and 3.2 kW, respectively. The investigation involved microstructure observations with the use of both light microscope and scanning electron microscope with energy dispersive spectroscopy (EDS) analysis of chemical composition and microhardness distribution measurements. It has been stated that laser beam welding allows to obtain Sc-modified AA2519-F weld of good quality, characterized by the presence of an equiaxed grain zone containing scandium-rich precipitates adjacent to the fusion boundary.
7
Content available remote Microstructure and mechanical properties of Sc-modified AA2519-T62 laser beam welded butt joints
Kosturek Robert, Grzelak Krzysztof, Torzewski Janusz, Wachowski Marcin, Śnieżek Lucjan
Advances in Materials Science
|
2022
|
Vol. 22, nr 4(74)
57--69
EN
The fundamental aim of the research is to investigate the microstructure and mechanical properties of the AA2519-T62 laser beam welded joints obtained with various values of welding velocity. For the constant value of laser power (3.2 kW) three joints have been produced with various values of welding velocity: 0.8, 1.1, and 1.4 m/min. The joints have been subjected to microstructure analysis (including both light and scanning electron microscope), microhardness measurements, tensile tests, and fractography of tensile samples. The established values of joint efficiency contain within the range of 55-66% with the highest value (66%) reported for the joint obtained with 1.1 m/min welding velocity. The produced welds have noticeable participation of pores, which tends to increase together with the value of welding velocity. In all cases, the failure has occurred in the fusion zone by ductile fracture.
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