Digital Control of Electrically Welded Pipe Manufacturing Technology in a Tesa 20–102 Mill

Metallurgist - In order to manufacture hot-reduced pipe from welded pipe billets in a continuous stretch-reducing mill (SRM) 20–102 coiled hot-rolled product is used of normal precision with...     

Modeling of Pipe–Soil Interaction and Its Application in Numerical Simulation

This paper presents three plasticity models that can be applied to numerically simulate pipe–soil interaction. They can be applied individually to evaluate the force–displacement response of a small plane-strain pipe section or in combination to simulate a long pipeline system. In the latter, numerous pipe–soil elements are attached to structural finite elements, each simulating localized foundation restraint along the pipeline. The three models are increasing in sophistication, mainly due to the manner in which they account for the behavior within an allowable combined loading surface. The first is based on traditional strain-hardening plasticity theory and therefore assumes a purely elastic response inside a single expandable yield surface. The second allows some plasticity due to the use of a bounding surface, and the third accounts for kinematic hardening through the introduction of a second smaller surface. The models are detailed in this paper, allowing for simple numerical implementation. Importantly, they are incorporated within the structural analysis of a pipeline and their potential to investigate generic pipeline system behavior is demonstrated. The applicability of the three models is interpreted theoretically and their differences shown through application for (1) a one pipe–soil interaction element and along (2) a 100?m segment of pipeline. The latter shows the practical application of these models to offshore pipeline engineering examples, with the influence of a free span behavior investigated. The ability to model complex cyclic loading is also shown.     

Interdiffusion Study in the Fe–Nb System

The diffusion characteristics of the Fe–Nb system were investigated using the diffusion couple technique. The average interdiffusion coefficient was calculated for the Fe₂Nb Laves and the FeNb μ phases. The possible diffusion mechanism was predicted by using the calculated values of the activation energy for diffusion. Kirkendall marker experiments were conducted to determine the relative mobilities of the species. Fe was found to have a faster diffusion rate than Nb in both phases.     

Phase Formation in the Ti–Al–C System during SHS

Russian Journal of Non-Ferrous Metals - The phase formation of Ti–Al–C powder mixtures with compositions close to MAX phases during self-propagating high-temperature synthesis (SHS) is...     

Solid-State Reactions of SiC–TiO2–MgO System and Phase Relations in SiC–SiO2–TiC–TiO2–MgO System

Powder Metallurgy and Metal Ceramics - Preliminary experiments revealed solid-state reactions in the SiC–TiO2–MgO system that resulted in forming TiC compound, providing, thus, a new...     

Icosahedral Ordering Induced by Cr in Al–Zn Alloy Liquid

Metallurgical and Materials Transactions A - Cr atoms can promote the formation of icosahedral short-range order (ISRO) in Al–Zn alloy liquid, which is believed to be the structural origin of...     

Phase Equilibria in Liquid Metal of the Cu–Al–Cr–O System

A thermodynamic analysis of phase equilibria in the Cu–Al–Cr–O system is carried out. Thermodynamic modeling of the liquidus surface of the Cu₂O–Al₂O₃–Cr₂O₃ oxide phase diagram is performed. To describe activities of an oxide melt, the approximation of the theory of subregular ionic solutions, the energy parameters of which were determined during modeling, is used. Melting characteristics of the CuCrO₂ compound are also evaluated in the course of the calculation. Coordinates of invariant equilibria points implemented in the Cu₂O–Al₂O₃–Cr₂O₃ ternary oxide system are established by the results of the calculation. Thermodynamic modeling of interaction processes in the Cu–Al–Cr–O system in occurrence conditions of a copper-based metal melt is also performed. The temperature dependence of the equilibrium constant of the reaction that characterizes the formation of the CuCrO₂ solid compound from components of the metal melt of the Cu–Al–Cr–O system is determined. The temperature dependence for the first-order interaction parameter (by Wagner) of chromium and oxygen dissolved in liquid copper is found. The results of thermodynamic modeling for the Cu–Al–Cr–O system are presented in the form of the solubility surface of components in metal, which makes it possible to attribute the quantitative variations in the metal melt concentration with qualitative variations in the composition of forming interaction products. It is determined by the results of modeling that particles of the |Al₂O₃, Cr₂O₃|_sol.sln solid solution are formed at valuable aluminum and chromium concentrations in the copper melt of the Cu–Al–Cr–O system as the main interaction product. The results of the investigation can be interesting for improving the technology process of smelting of chromium bronzes.     

Component-Interaction Mechanism in the Quasibinary HfB2–Cr System

Powder Metallurgy and Metal Ceramics - The interaction of hafnium boride and chromium in the HfB2–Cr system is studied. Solid-phase interaction occurs at temperatures up to 1650 ±...     

Phase Equilibria in the Ternary Al–Ti–Pt System. IV. Vertical Sections in the Ternary Al–Ti–Pt System in the Composition Range 0–50 at.% Pt

Powder Metallurgy and Metal Ceramics - Physicochemical analysis results for alloys in the Al–Ti–Pt system at 0–50 at.% Pt that were cast and annealed at subsolidus temperatures...     

Phase Equilibria in the Ternary Al–Ti–Pt System. I. Solidus Surface of the Al–Ti–Pt System in the Range 0–50 at.% Pt

Powder Metallurgy and Metal Ceramics - The nature of phase equilibria has been examined for the first time in the Al–Ti–Pt system in the range 0–50 at.% Pt at subsolidus...     

Phase Equilibria in the Ternary Al–Ti–Pt System. II. Liquidus Surface of the Al–Ti–Pt System in the Compositions Range 0–50 at.% Pt

Powder Metallurgy and Metal Ceramics - The liquidus surface of the Al–Ti–Pt system has been constructed for the first time on the composition triangle based on studies of the structure...     

Explicit Power Formula for the Darcy–Weisbach Pipe Flow Equation: Application in Optimal Pipeline Design

Although the Darcy–Weisbach equation combined with the Colebrook–White semitheoretical formula for calculating the friction coefficient is a highly accurate generalized pipe-water flow resistance equation, most users prefer the use of simple, explicit power law form formulas. Because of their simplicity (despite their limitations) the purely empirical power formulas of Hazen–Williams and Manning remain the most popular pipe flow resistance equations used in routine hydraulic engineering applications. In this paper, a new simple power law form formula is derived to approximate the generalized Darcy–Weisbach combined with the Colebrook–White equation. The two main pipe flow parameters, such as the discharge (or velocity) and the diameter, appeared explicitly in the proposed formula. The suggested power-form formula compared with the Darcy–Weisbach and Coolbrook–White equation yields a maximum relative error of about ±4.5%. The power-form suggested formula is dimensionally homogeneous and its accuracy is sufficient for practical engineering applications. A correction factor is introduced for the variation of kinematic viscosity with temperature. The usefulness of the formula is demonstrated in an application concerning the optimal design of a delivery pipeline with pumping. The power form of the friction formula facilitates the formulation of the problem leading to the derivation of a simple equation from which the economic diameter is explicitly calculated.     

Composition and Crystalline Structure of Ternary Phases in the Ta–Ni–Al System

Russian Journal of Non-Ferrous Metals - The composition and crystal structure of compounds produced by self-propagating high-temperature synthesis (SHS) from the 5Ta–2Ni–3Al (at %)...     

Kinetic Transition During Ferrite Growth Induced by Interfacial Solute Segregation in an Fe–C–Mn–Si Alloy

The kinetic transition of partitionless proeutectoid ferrite transformation from austenite, experimentally reported earlier in an Fe–C–Mn–Si alloy, is simulated incorporating interfacial segregation of carbon and alloy elements. The time-dependent diffusion equations of solutes are solved within the α/γ interface to evaluate the transient effects of solute accumulation on the migration of interface. The carbon concentration at the interface in the matrix decreased faster and the interface migration ceased, or the so-called stasis occurred, when the carbon concentration gradient in the immediate front of the interface turned to null or reversed. This can happen earlier than the partitionless-to-partitioned growth transition predicted from conventional theory in the absence of interfacial segregation, depending upon austenite grain size, i.e., the extent of soft impingement of carbon diffusion fields in the matrix in which a large carbon supersaturation remained. The subsequent transformation may be resumed accompanying the bulk partitioning of Mn (and probably Si) and/or nucleation of new ferrite crystals.

     

Alloy Structure and Equilibrium Phase Diagram for the Sc–Ru–Rh System. Part 7. Polythermal Sections in the Sc–Ru–Rh System

DTA, XRD, metallography, and electron-probe microanalysis have been applied to study phase compositions of cast and annealed alloys (annealing at subsolidus temperatures of 1400°C (composition range 0-50 at.% Sc) and 930°C (composition range 50-100 at.% Sc)) and construct polythermal sections for the Sc Ru Rh ternary system on the isoconcentrates 75 at.% Sc, 65 at.% Rh, and beam Ru:Rh = 1:1, as well as isoconcentrates for 5.0 ± 0.3 at.% Ru and 5 at.% Rh in the region of 50-100 at.% Sc. The sections reveal characteristic features of the phase diagram structure for this ternary system, in particular temperature ranges for crystallization and the types of phase transformation within them.