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Effect of Arc Strikes on High Strength Low Alloy Steels Welded by SMAW

Fydrych Dariusz, Raczko Przemysław, Świerczyńska Aleksandra, Landowski Michał, Wolski Adrian, Rogalski Grzegorz

Advances in Science and Technology. Research Journal

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2023

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Vol. 17, no 3

160--169

EN

Wet welding with covered electrodes (Shielded Metal Arc Welding-SMAW) is the most commonly used method of carrying out welding repair works in a water environment. Limited visibility and the inability to move freely under water result in an increased risk of formation of welding imperfections such as lack of fusion, lack of penetration and arc strikes. The work focused on changes in the properties and structure of steel subjected to the impact of short (0.2 s) arc ignitions generated by covered electrodes in air and under water for three high strength steel grades: S460N, S460M and S500MC. Visual tests, macroscopic and microscopic metallographic tests, microhardness measurements and diffusible hydrogen content in deposited metal determination were performed. A significant influence of the environment on changes in the morphology and microhardness of steel in the vicinity of arc strikes was found. The microhardness of the areas covered by the rapid thermal cycle caused by SMAW increased from 200-230 HV0.5 to 400-500 HV0.5 depending on the steel grade. The presence of welding imperfections: cavities and cracks were detected. The susceptibility of all steel grades subjected to short thermal cycles to cracking was confirmed by the results of measurements of the diffusible hydrogen content: 38.6 ml/100g and 84.5 ml/100 g for air and water environment, respectively. No influence of changes in the welding current on the behavior of the material in the tested conditions was found. The conducted research shows that leaving arc strikes on the structure may have serious consequences and cause a failure.

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Influence of stick electrode coating’s moisture content on the diffusible hydrogen in underwater wet shielded metal arc welding

Klett J., Hassel T.

Advances in Materials Science

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2020

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Vol. 20, nr 4(66)

27--37

EN

In shielded metal arc welding, the major factors influencing hydrogen uptake into the weld metal are (i) the hydrogen content of the base metal, (ii) hydrogen input by the welding consumable, and (iii) the hydrogen introduced by the atmosphere surrounding the arc process. In this study, the relative contribution of these factors is investigated and compared to each other for the case of underwater wet shielded metal arc welding. To assess the influence of the stick electrode’s moisture (capillary introduced water during handling operations) on the diffusible hydrogen in wet welded samples, wet and dry electrodes were welded at four different water depths. The moisture was absorbed through the sharpened electrode tip only, to ensure close to service conditions. The results show that the moist stick electrode coatings lead to 22.6% higher average diffusible hydrogen content in the weld metal (0.5 m water depth an average). However, the effect disappears with increasing water depths (no difference in 60 m water depth).

3

Inclusions in steel coated electrodes welds of car body

Węgrzyn T., Miros M.

Transport Problems

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2007

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T. 2, z. 4

87-92

EN

The goal of this project (BK-284/RT1/2007) is to chose the proper method of car body welding. SMAW could be treated as the main method used in the transport industry. Properties of metal weld deposits depend on many conditions. This paper attempts to study first of all the role of oxide inclusion sites on the transformation austenite-acicular ferrite in steel weld metal deposits and their toughness. Properties of metal weld deposits depend on the amount of acicular ferrite in them. For good toughness over a range of temperatures, metal weld deposits should have a high amount of acicular ferrite. Different basic and rutile electrodes were used in order to obtain different as-deposited weld compositions. Impact toughness tests of various deposits were carried out. The microstructure of the welds with different oxygen levels, the inclusion size distribution and approximate chemical composition of inclusions are characterized. Most observations and measurements were done with a scanning electron microscope equipped with an energy-dispersive X-ray spectrometer. The result of the present study implies that it is advantageous to keep oxygen contents in basic and rutile deposits as low as possible when well-developed microstructures of acicular ferrite are desired.

PL

Celem artykułu (BK-284/RT1/2007) jest wybór właściwej metody spawania nadwozi samochodowych. Spawanie SMAW może być traktowane jako główna metoda spawania sprzętu transportowego. Właściwości stopiwa elektrodowego zależą od wielu czynników. W artykule przeanalizowano wpływ wtrąceń tlenkowych na przemianę austenit-ferryt AF oraz na udarność stopiwa. Właściwości stopiwa zależą od ilości zawartego w nim ferrytu AF. W celu zapewnienia wysokiej udarności stopiwa w szerokim zakresie temperatur, powinna znajdować się w nim duża ilość ferrytu AF. Do wykonania różnych rodzajów stopiw zastosowano rozmaite odmiany elektrod zasadowych oraz rutylowych. Przebadano udarność stopiw wykonanych różnymi metodami. Przeanalizowano mikrostrukturę stopiw o różnych zawartościach tlenu, określono procentowy rozkład wielkości wtrąceń znajdujących się w stopiwach, a także skład chemiczny ujawnionych wtrąceń. Większość obserwacji oraz badań przeprowadzono z użyciem elektronowego mikroskopu skaningowego, wyposażonego w przystawkę do mikroanalizy rentgenowskiej. Uzyskane wyniki wskazują na to, iż korzystnie jest utrzymywać zawartość tlenu w stopiwie elektrod zasadowych, a także rutylowych na możliwie niskim poziomie, kiedy wymagana jest dobrze rozwinięta struktura ferrytu AF.