Effect of structural anisotropy of ferrite-bainite pipe steel on mechanical properties in tensile and impact bending tests

Metallurgist - The mechanical properties of thick rolled plate for main pipelines with a ferrite-bainite microstructure in different directions over the plate plane are determined, mechanical...     

Effect of the Carbon Content of Low-Alloy Steels on the Surface Quality of Continuous-Cast Semifinished Products and Rolled Plates

An analysis is made of the effect of the carbon content of low-alloy steels on the damage done to slabs and rolled plates of those steels by surface defects. The effect of carbon content on the formation of cracks of different morphology is evaluated for the conditions that exist at the Azovstal' Metallurgical Combine.     

Structure and properties of low-alloy steels after controlled rolling

Conclusions To obtain the best combination of strength and toughness due to grain refining and controlled precipitation hardening with particles of carbonitride phase, controlled rolling is carried out in the lower range of the austenite region, followed by cooling at a certain rate. This treatment can be called high-temperature thermomechanical treatment for low-alloy steels. The effect of thermomechanical treatment (controlled rolling) increases as the initial and final rolling temperatures are lowered and the degree of deformation in the last passes is increased, and also with the addition of elements that inhibit the recrystallization of austenite (Nb, V, Ti).The effect of controlled rolling can be utilized most completely only for steels with carbonitride-forming elements that promote grain refining, inhibit recrystallization of austenite, and thus strengthen the steel due to precipitation hardening and increase its resistance to brittle fracture.I. P. Bardin Central Scientific-Research Institute of Ferrous Metallurgy. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 2–11, December, 1975.     

Selecting Portfolios of Water Supply and Demand Management Strategies Under Uncertainty—Contrasting Economic Optimisation and ‘Robust Decision Making’ Approaches

Planning appropriate portfolios of new water supplies and demand management measures requires considering a wide array of options and their interactions over a largely unknown future. Various modelling-assisted approaches are available to help this planning process. This paper applies two such frameworks to the UK’s Thames water resource system and compares their methods and outputs: how they consider uncertainty, how they represent supply and demand management options, and what plans each recommends. The first method is the current England and Wales industry standard: annual least-cost capacity expansion optimisation over a 25 to 30 year time horizon considering capital, operating (fixed and variable), social and environmental costs. The second approach uses stochastic simulation and regret analysis to select a preferred alternative, then statistical cluster analysis to identify causes of system failure enabling further plan improvement. When applied iteratively with system planners this second approach is referred to as Robust Decision Making (RDM). The economic optimisation approach considers all plausible combinations of supply and conservation schemes and recommends the least-cost schedule of their implementation. Our RDM application considers a smaller number of options but makes a more detailed assessment of the effect of uncertainty (supply, demand and energy price uncertainty were considered) on multiple criteria of system performance. The simulation-based approach also enables more realistic interaction amongst supply and demand management schemes. Both approaches recommended different plans which we explain by discussing the benefits and limitations of each. Joint application is recommended to produce least-cost plans that are robust considering multiple criteria of performance across a wide range of futures.     

Study of the mechanical characteristics of low-carbon plate steels

The Azovstal’ Metallurgical Combine has conducted tests of the production of plates of low-carbon (0.06–0.08% C) low-alloy steels 06GBD and 06G2B. The plates, ranging up to 45 mm in thickness and having yield points ≥390 and ≥440 N/mm², respectively, are intended for use in structures employed for critical applications. Both steels are microalloyed with niobium, vanadium, molybdenum, and additions of copper. It is shown that in the quenched-and-tempered state the two steels fully conform to the specifications. The plates are characterized by excellent cold resistance, impact toughness, and weldability (C_e = 0.34–0.37 for steel 06GBD and C_e = 0.38–0.41 for steel 06G2B) and satisfactory values of the ratio σ _y/σ _u (≤0.90 for plates with a thickness ≤20 mm and ≤0.85 for plates with a thickness >20 mm). The construction of serial curves describing impact work and the percentage of the ductile component in the fracture of Charpy specimens prepared from plates of steel 06GBD showed that the plates have a high resistance to brittle fracture (impact work was at least 145 J at ?70°C, and the percentage of ductile fracture was 100% for 14-mm-thick plates and 80% for 32-mm-thick plates).     

Effect of equal-channel multiangular pressing and heat treatment on the properties of an Nb-Ti-based superconductor

Effect of preliminary deformation induced by equal-channel multiangular pressing (ECMAP) in combination with hydroextrusion, drawing, and heat treatment on the structure and physicomechanical properties of a superconductor wire based on Nb-60 at % Ti alloy is studied. The optimal regime of ECMAP deformation is established.     

Hydrogas dynamics of metal refining in intermediate ladles

A three-dimensional model is proposed for the hydrogas-dynamic phenomena within the intermediate ladle of a continuous-casting machine. The results—the distribution of the current function and the velocity field—permit quantitative estimation of the increase in the transfer coefficient at the slag-metal boundary. These data may be used in intermediate-ladle design. By this means, the content of nonmetallic inclusions in continuous-cast billet may be significantly reduced.     

On the Nature of the Effect of Interfaces between Constituents on the Strength of Fibrous Copper–Niobium–Titanium Composite

This paper describes the regularities of the variation of the mechanical characteristics of fibrous copper- and copper-alloy-based composites reinforced by niobium–titanium alloy fibers as a function of the state of the interfaces between its constituents under different conditions of deformation and thermal treatment.     

Existence of solutions of the algebro-differential equations

Consideration was given to a finite-dimensional system of algebro-differential equations with discontinuities. Solution was determined in a general form, and the existence theorem was proved for the nondegenerate case.