Laser beam welding of a CoCrFeNiMn-type high entropy alloy produced by self-propagating high-temperature synthesis

Fiber laser beam welding of a CoCrFeNiMn-type high entropy alloy (HEA) produced by self-propagating hightemperature synthesis (SHS) was reported in this work. The SHS-fabricated alloy was characterized by both ∼2 times reduced Mn content in comparison with that of the other principal components and the presence of impurities including Al, C, S, and S

Effect of Microstructure Transformations on Fatigue Properties of Laser Beam Welded Ti‐6Al‐4V Butt Joints Subjected to Postweld Heat Treatment

The effect of postweld heat treatment (PWHT) on 2.6‐mm‐thick Ti‐6Al‐4V butt joints that were welded using a continuous‐wave 8‐kW ytterbium fibre laser was studied in terms of the microstructure, microtexture, number of welding defects, microhardness, residual stress distribution and high cycle fatigue (HCF) properties. Five types of heat treatments in the temperature range of 540–920°C are investigated. The main reasons leading to fatigue life deterioration after the laser welding process are discussed, and possible guidelines for further improvement of the HCF behaviour by a subsequent suitable type of PWHT are provided. Low‐temperature annealing (T  750°C) lead to the transformation of a strong martensitic structure in the fusion zone (FZ) into more ductile coarse lamellar, which is more beneficial for fatigue performance. A suitable type of PWHT can increase the fatigue limit of a laser‐welded Ti‐6Al‐4V butt joint by 10%; however, a slight decrease in static strength should be considered. The effect of stress relief at elevated temperatures is studied

Schöne Steine – und strahlende Gesichter: ein ungewöhnlicher Einsatz

Der Inhaber einer Recyclingfirma hatte diverse Kisten unterschiedlichen Inhalts erworben. Bei der Sichtung zu Hause fielen ein Kasten mit dem Strahlenwarnzeichen und der Bezeichnung „Radioaktiv Klasse I“ und mehrere evtl. radioaktiv strahlende Gesteinsbrocken auf. Die integrierte Leitstelle (ILS) entsandte nach „ABC‑2, Gefahrstoff/undefinierbarer Gegenstand“ und dem Zusatz „Uranfund“ um 16:40 Uhr die Feuerwehr (Fw) mit dem Fachberater Gefahrgut und einer CBRN(chemische, biologische, radiologische und nukleare Gefahren)-Messeinheit

Geologia e petrografia dos diques máficos relacionados com o magmatismo pós-colisional da região de Vila Nova, RS

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Laser beam welding of a Ti-15mo/TIB metal-matrix composite

A Ti-15Mo/TiB metal-matrix composite was produced by spark plasma sintering at 1400 °C. The fractions of the elements in the initial powder mixture were 80.75 wt.% Ti, 14.25 wt.% Mo, and 5 wt.% TiB2. The initial structure of the synthesized composite was composed of bcc titanium matrix and needle-like TiB reinforcements with an average thickness of 500 ∓ 300 n

Fatigue behaviour of a laser beam welded CoCrFeNiMn-type high entropy alloy

Laser beam welding was used to produce butt joints from the CoCrFeNiMn-type high entropy alloy. The alloy in the initial condition had an fcc single-phase coarse-grained structure. Laser welding resulted in the M7C3-type carbide particles precipitation resulted in a considerable increase in microhardness from 150 HV 0.5 for the as-sintered condition to 205 HV 0.5 in the fusion zone. Laser beam welding had a negligible effect on both static mechanical properties and fatigue behaviour of the allo

Compression behaviour of wire+ arc additive manufactured structures

Increasing demand for producing large-scale metal components via additive manufacturing requires relatively high building rate processes, such as wire + arc additive manufacturing (WAAM). For the industrial implementation of this technology, a throughout understanding of material behaviour is needed. In the present work, structures of Ti-6Al-4V, AA2319 and S355JR steel fabricated by means of WAAM were investigated and compared with respect to their mechanical and microstructural properties, in particular under compression loading. The microstructure of WAAM specimens is assessed by scanning electron microscopy, electron back-scatter diffraction, and optical microscopy. In Ti-6Al-4V, the results show that the presence of the basal and prismatic crystal planes in normal direction lead to an anisotropic behaviour under compression. Although AA2319 shows initially an isotropic plastic behaviour, the directional porosity distribution leads to an anisotropic behaviour at final stages of the compression tests before failure. In S355JR steel, isotropic mechanical behaviour is observed due to the presence of a relatively homogeneous microstructure. Microhardness is related to grain morphology variations, where higher hardness near the inter-layer grain boundaries for Ti-6Al-4V and AA2319 as well as within the refined regions in S355JR steel is observed. In summary, this study analyzes and compares the behaviour of three different materials fabricated by WAAM under compression loading, an important loading condition in mechanical post-processing techniques of WAAM structures, such as rolling. In this regard, the data can also be utilized for future modelling activities in this direction