Shape Indexes for Dieless Forming of the Elongated Forgings with Sharpened End by Tensile Drawing with Rupture

Kukhar, Volodymyr; Grushko, A.V.; Vishtak, Inna

doi:10.4028/www.scientific.net/ssp.284.408

Cited by 38 publications

(20 citation statements)

References 22 publications

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“…Now, taking f M = 16 vol.%, the M s temperature was calculated as 42 °C. The tensile stress was calculated according to Equations (2)–(6) using the following parameters: T sol = 1320 °C [ 49 ], E = 200 GPa [ 62 ], ν = 0.22 [ 63 ], α A = 18.6 × 10 −6 K −1 , and α M = 13.9 × 10 −6 K −1 [ 64 ]. The volumetric effect of austenite→martensite transformation was derived from the equation: Δ V A → M = 2.5–1.08·(C γ %) [ 65 ] assuming a carbon content in austenite (C γ %) of 1.50 wt.%.…”

Section: Discussionmentioning

confidence: 99%

Evaluation of the Microstructure, Tribological Characteristics, and Crack Behavior of a Chromium Carbide Coating Fabricated on Gray Cast Iron by Pulsed-Plasma Deposition

et al. 2021

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The structural and tribological properties of a protective high-chromium coating synthesized on gray cast iron by air pulse-plasma treatments were investigated. The coating was fabricated in an electrothermal axial plasma accelerator equipped with an expandable cathode made of white cast iron (2.3 wt.% C–27.4 wt.% Cr–3.1 wt.% Mn). Optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction analysis, microhardness measurements, and tribological tests were conducted for coating characterizations. It was found that after ten plasma pulses (under a discharge voltage of 4 kV) and post-plasma heat treatment (two hours of holding at 950 °C and oil-quenching), a coating (thickness = 210–250 µm) consisting of 48 vol.% Cr-rich carbides (M7C3, M3C), 48 vol.% martensite, and 4 vol.% retained austenite was formed. The microhardness of the coating ranged between 980 and 1180 HV. The above processes caused a gradient in alloying elements in the coating and the substrate due to the counter diffusion of C, Cr, and Mn atoms during post-plasma heat treatments and led to the formation of a transitional layer and different structural zones in near-surface layers of cast iron. As compared to gray cast iron (non-heat-treated and heat-treated), the coating had 3.0–3.2 times higher abrasive wear resistance and 1.2–1208.8 times higher dry-sliding wear resistance (depending on the counter-body material). The coating manifested a tendency of solidification cracking caused by tensile stress due to the formation of a mostly austenitic structure with a lower specific volume. Cracks facilitated abrasive wear and promoted surface spalling under dry-sliding against the diamond cone.

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Section: Discussionmentioning

confidence: 99%

Evaluation of the Microstructure, Tribological Characteristics, and Crack Behavior of a Chromium Carbide Coating Fabricated on Gray Cast Iron by Pulsed-Plasma Deposition

et al. 2021

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“…Alternative technologies for producing the boride coatings, which have none of the inherent disadvantages of the CTT (process time, low productivity, the need to heat the entire workpiece, deformation and warping, the need for expensive equipment, etc. ), are the boriding methods using concentrated energy fluxes (CEFs) [ 17 , 18 , 19 , 20 ]. In [ 21 ], a method is proposed for electroerosive boriding including applying a boron-containing surface coating by an electrode made in the form of a rod blown with a cooler.…”

Section: Introductionmentioning

confidence: 99%

Assessment of Technological Capabilities for Forming Al-C-B System Coatings on Steel Surfaces by Electrospark Alloying Method

et al. 2021

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In this paper, the possibility of applying the electrospark alloying (ESA) method to obtain boron-containing coatings characterised by increased hardness and wear resistance is considered. A new method for producing such coatings is proposed. The method consists in applying grease containing aluminium powder and amorphous boron to the surface to be treated and subsequently processing the obtained surface using the ESA method by a graphite electrode. The microstructural analysis of the Al-C-B coatings on steel C40 showed that the surface layer consists of several zones, the number and parameters of which are determined by the energy conditions of the ESA process. Durametric studies showed that with an increase in the discharge energy influence, the microhardness values of both the upper strengthened layer and the diffusion zone increased to Wp = 0.13 J, Hµ = 6487 MPa, and Wp = 4.9 J, Hµ = 12350 MPa, respectively. The results of X-ray diffraction analysis indicate that at the discharge energies of 0.13 and 0.55 J, the phase composition of the coating is represented by solid solutions of body-centred cubic lattice (BCC) and face-centred cubic lattice (FCC). The coatings obtained at Wp = 4.9 J were characterised by the presence of intermetallics Fe4Al13 and borocementite Fe3 (CB) in addition to the solid solutions. The X-ray spectral analysis of the obtained coatings indicated that during the electrospark alloying process, the surface layers were saturated with aluminium, boron, and carbon. With increasing discharge energy, the diffusion zone increases; during the ESA process with the use of the discharge energy of 0.13 J for steel C40, the diffusion zone is 10–15 μm. When replacing a substrate made of steel C40 with the same one material but of steel C22, an increase in the thickness of the surface layer accompanied by a slight decrease in microhardness is observed as a result of processing with the use of the ESA method. There were simulated phase portraits of the Al-C-B coatings. It is shown that near the stationary points in the phase portraits, one can see either a slowing down of the evolution or a spiral twisting of the diffusion-process particle.

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“…For the manufacture of structural sections with required service properties different fabrication methods are used [1,[6][7][8][9][10][11][12]: skew roll piercing process, pilger process, Fretz-Moon pipe process, induction welding process, spirally bent strip welding. Hot-finished process (HFP) [13][14][15][16] and cold-formed process (CFP) [7,[10][11][12] is the most common manufacturing for RHS. These consist in the roll-forming of circular tube from a strip, welding of edges and re-forming into rectangular tube section (round to square or rectangular section forming) with heating (HFP) or without heating (CFP), respectively.…”

Section: Introductionmentioning

confidence: 99%

FEM simulation of bending and torsion tests of similar size RHS but of the different production options

et al. 2021

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The paper implements a method for analyzing the stress-strain state of rectangular hollow sections (RHS) by finite-element modeling (FEM) of tests for three-point bending and torsion. Design schemes, 3-D solid-state and deformable models have been developed using the automated analysis and CAD/CAE system software, made it possible to obtain equivalent stress distributions and displacements in models. A simulation of tests for RHS with a cross section of 40 mm × 50 mm, manufactured in two ways, was carried out: (a) by direct-forming of galvanized steel strips on roll-forming mill in a semi-closed section with a longitudinal gap of 0.5 mm between the edges formed on a 40 mm web (DF-RHS); (b) similar direct-forming to the closed section and next welding the edges to a longitudinal weld along the web middle of 50 mm (DFW-RHS). RHS with various wall thicknesses (t = 1.93 mm, 1.84 mm and 0.7 mm) was investigated, given the design features that depend on the manufacturing processes of structural sections. It was found DFW-RHS is stiffer by at least 50% compared to DF-RHS, which allows to savings the metal by reducing the RHS wall thickness by 62% while maintaining the same stiffness and ensuring high strength of structural section.

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Shape Indexes for Dieless Forming of the Elongated Forgings with Sharpened End by Tensile Drawing with Rupture

Cited by 38 publications

References 22 publications

Evaluation of the Microstructure, Tribological Characteristics, and Crack Behavior of a Chromium Carbide Coating Fabricated on Gray Cast Iron by Pulsed-Plasma Deposition

Evaluation of the Microstructure, Tribological Characteristics, and Crack Behavior of a Chromium Carbide Coating Fabricated on Gray Cast Iron by Pulsed-Plasma Deposition

Assessment of Technological Capabilities for Forming Al-C-B System Coatings on Steel Surfaces by Electrospark Alloying Method

FEM simulation of bending and torsion tests of similar size RHS but of the different production options

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