Kaynak Teknolojisi Uygulama ve Araştırma Merkezi
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Öğe Mechanical and ballistic performance of high-hardness armor steels welded with ASS-LHF sandwich joint design(Elsevier Ltd, 2025) Gürol, Uğur; Çelik, Ceren; Çoban, Ozan; Göçmen, Müesser; Koçak, MustafaArmor steels are widely recognized for their exceptional mechanical and ballistic performance, particularly in the fabrication of armored vehicles. Austenitic stainless steel (ASS) wires are commonly used in their welding processes to mitigate hydrogen-induced cracking. However, joints formed using ASS often suffer from reduced ballistic performance due to the strength mismatch (undermatching) compared to the base material. This study explores the application of butt joints, integrating low hydrogen ferritic (LHF) deposits between softer ASS weld layers, which can be expressed as sandwich layer design, in gas metal arc welded (GMAW) armor steel plates. The mechanical properties were evaluated through hardness, tensile, and Charpy V-notch impact tests. Ballistics test performances were measured using depth of penetration (DoP) and width of penetration (WoP) values. The microstructural analysis utilized stereo, optical, and scanning electron microscopes. The results demonstrated that the sandwich joint configuration met the Charpy-V impact toughness requirements of the base metal, achieving 31.4 J and 65 J at −40 °C for the WM and HAZ regions, respectively, compared to 20 J for the base material. Moreover, this innovative joint design effectively combined the high toughness and ductility of austenitic wire, reaching a low DoP value of 7.2 mm, with the superior strength of ferritic filler metal, which contributes to a low WoP value of 12.5 mm and a joint efficiency of 48 %. By combining these properties, the joint design significantly enhances ballistic performance in welded regions, traditionally considered vulnerable to ballistic threats, without compromising overall mechanical integrity.Öğe Microstructural and mechanical characterizations of weld metal of S960QL ultra high strength steel joints obtained with different multi-pass laying techniques using GMAW(Institute of Physics, 2024) Mert, Tolga; Gürol, Uğur; Tümer, Mustafa15 mm thick ultra-high strength steel plates with 960 MPa yield strength were welded using different multi-pass laying techniques (i.e., stringer and weaving beads) with torch manipulation. Weld metals obtained were compared using different mechanical (i.e., micro tensile tests and Vickers hardness maps) and microstructural (i.e., optical microscope, scanning electron microscope, x-ray diffraction, electron backscatter diffraction) characterization techniques. Coarser grains and acicular ferrite were observed in weld metal obtained with the weaving pass procedure. There were hardness differences in the face and root passes of both weld metals. Yet, hardness values were 19% and 11% higher for the face and root regions of the joint obtained by stringer pass procedure, respectively. Fractographs of micro tensile test specimens revealed dimples depicting ductile network structure for both joints.
