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Development and implementation of robotized wire arc additive repair of a gas turbine diaphragm

Steckowicz Piotr, Pyrzanowski Paweł, Bulut Efe

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2024

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Vol. 72, nr 2

art. no. e147920

EN

The current practice of reconstruction of oxidized turbine parts (due to hot corrosion) using arc welding methods facilitates restoration of the nominal shapes and dimensions, as well as other attributes and features. Intense development of 3D additive methods and techniques contributes to the repair/modification of different parts including gas turbine (GT) hardware. The article proves the viability of the concept of using a robotized additive arc welding metal active gas (MAG) process to repair and modify gas turbine diaphragms using different filler materials from the substrate. The industrialized robotic additive process (hybrid repair) shows that very good results were achieved if the diaphragm is cast of nickel-iron and the filler material for welding the passes is austenitic stainless steel (for instance 308 LSi). This is one of the novelties introduced to the repair process that was granted a patent (US11148235B2) and is already implemented in General Electric Service Centers.

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The effects of arc voltage and shielding gas type on the microstructure of wire arc additively manufactured 2209 duplex stainless steel

Kemény Dávid Miklós, Sándor Bence, Varbai Balázs, Katula Levente Tamás

Advances in Materials Science

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2023

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Vol. 23, nr 4(78)

62--82

EN

Duplex stainless steels (DSSs) are widely used due to their corrosion resistance. Austenite and ferrite determine the excellent properties. Ferrite provides strength and good corrosion resistance, while austenite provides toughness and weldability. During our research,samples were producedwith ER 2209 duplex steel wire using wirearc additive manufacturing (WAAM). Two different 17V and 19V arc voltages were used during the production. Two shielding gases were used for each voltage: M12-ArC-2.5 and M12-ArHeC-20/2. The research aimed to determine the ferrite ratio as a function of the welding parameters. The ferrite(or austenite)content must be between 30% and 70% for duplex stainless steel welds, according to the ISO 17781 standard.Based on our research, it can be stated that the austenite ratio increases as the voltage increases, thus failing to fulfill the standard's requirements. The helium content reduced the ferrite ratio even when the 17V voltage was used due to the gas's higher ionizationpotential. During the metallographicexamination, our welded samples met the standardrequirements for the austenite content for17V arc voltage and M12-ArC-2.5 shielding gas. The ferrite content in the entire sample cross-sectionfell between 30-42% duringferitscopeand image analysis measurements. These welding parameters can be recommended for industrial applications.

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The chemical composition of the weld deposit in metallic products made using wire arc additive manufacturing methods

Pańcikiewicz Krzysztof

Biuletyn Instytutu Spawalnictwa w Gliwicach

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2022

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Vol. 66, No. 4

53--59

EN

The article presents an analysis concerning the obtainment of weld deposit properties (declared by the manufacturer of the filler metal) in the finished products made using additive manufacturing processes involving the application of arc welding methods. The use of an incompatible base material during the initial stage of the additive manufacturing process led to significanchanges in the chemical composition of the obtained layer (when compared with the chemical composition of the weld deposit declared by the producer of the filler metal). The dilution of the partly melted incompatible base material with the weld deposit resulted in the obtainment of a layer characterised by different properties (i.e. microstructure, hardness, corrosion resistance) than those declared by the manufacturer of the filler metal. The results obtained in the tests described in the article were compared with the requirements related to the making of the weld deposit subsequently subjected to the analysis of chemical composition (in accordance with the PN-EN ISO 6847 standard). The requirements specified in the aforesaid standard are used during tests related to, among other things, the conformity assessment procedure applied when qualifying filler metals.

PL

W artykule przedstawiono analizę problemu związanego z otrzymywaniem, deklarowanych przez producenta materiału dodatkowego, cech stopiwa w gotowych wyrobach kształtowanych przyrostowo z użyciem łukowych metod spawalniczych. Zastosowanie niedopasowanego materiału podstawowego do kształtowanego przyrostowo wyrobu na początkowym etapie wytwarzania prowadzi do istotnych zmian składu chemicznego pomiędzy uzyskaną warstwą a deklarowanym składem chemicznym stopiwa. Na skutek wymieszania nadtopionego niedopasowanego materiału podstawowego ze stopiwem uzyskiwana jest warstwa, która charakteryzuje się innymi cechami (tj. mikrostruktura, twardość, odporność na korozję) niż deklarowane przez producenta spoiwa. Wyniki te odniesiono do wymagań dotyczących wykonania stopiwa do analizy składu chemicznego, zgodnie z PN-EN ISO 6847, stosowanych do badania stopiwa, m.in. w ramach procedury oceny zgodności podczas kwalifikowania typu materiału dodatkowego do spawania.