Structure and properties of a layered steel/vanadium alloy/steel composite prepared by high-pressure torsion

The microstructure and hardness of a layered steel 08Kh17T/V–10Ti–5Cr/steel 08Kh17T composite, which was prepared by torsion under a high hydrostatic pressure at temperatures of 20, 200, and 400°C, have been studied. Severe plastic deformation under used conditions is shown to provide good joining of layers, which is accompanied by their substantial hardening (from 2.0 to 3.5 times). During deformation at temperatures of 20 and 200°C, fragmentation of the vanadium alloy layer into thinner layers is observed; at 400°C, mainly a plane interface between the vanadium alloy and the steel layers is formed.     

Structure and Properties of High-Temperature Multilayer Hybrid Material Based on Vanadium Alloy and Stainless Steel

The present work is devoted to the development of new structural composite material having the unique complex of properties for operating in ultrahard conditions that combine high temperatures, radiation, and aggressive environments. A new three-layer composite tube material based on vanadium alloy (V-4Ti-4Cr) protected by stainless steel (Fe-0.2C-13Cr) has been obtained by co-extrusion. Mechanism and kinetics of formation as well as structure, composition, and mechanical properties of “transition” area between vanadium alloy and stainless steel have been studied. The transition area (13- to 22-µm thick) of the diffusion interaction between vanadium alloy and steel was formed after co-extrusion. The microstructure in the transition area was rather complicated comprising different grain sizes in components, but having no defects or brittle phases. Tensile strength of the composite was an average 493 ± 22 MPa, and the elongation was 26 ± 3 pct. Annealing at 1073 K (800 °C) increased the thickness of transition area up to 1.2 times, homogenized microstructure, and slightly changed mechanical properties. Annealing at 1273 K (1000 °C) further increased the thickness of transition area and also lead to intensive grain growth in steel and sometimes to separation between composite components during tensile tests. Annealing at 1073 K (800 °C) is proposed as appropriate heat treatment after co-extrusion of composite providing balance between diffusion interaction thickness and microstructure and monolithic-like behavior of composite during tensile tests.

     

Evolution of the structure and mechanical properties of a bulk-nitrided corrosion-resistant ferritic steel upon tempering in the temperature range of 400–700°C

Methods of the X-ray diffraction analysis and electron microscopy were used to study changes in the structural phase state and mechanical properties of bulk-nitrided 08Kh17T steel (0.08 wt % C, 17 wt % Cr, 0.8 wt % Ti, 0.5 wt % Si, 0.8 wt % Mn, 0.025 wt % S, and 0.035 wt % P) upon tempering in the temperature range of 400–700°C. The changes in the mechanical properties of the nitrided steel upon tempering are associated with the predominance of either the solid-solution or precipitation strengthening, i.e., with the presence of martensite in the steel structure at low temperatures of tempering and the precipitation of particles of Cr₂N nitrides of different dispersity upon increasing the tempering temperature. The greatest increase in the ultimate tensile strength and yield stress (1.8–2.5 times) at a satisfactory plasticity (no less than 10%) of the bulk-nitrided steel is achieved by tempering bulk-nitrided steel in a temperature range of 600–700°C.     

Estimation of the notch sensitivity of a nitrided steel by acoustic emission

The notch sensitivity of sheet corrosion-resistant 08Kh17T steel is estimated in the states before and after high-temperature (1000–1100°C) internal nitriding during tensile tests accompanied by the measurement of acoustic emission signals. A crack in the steel is shown to propagate according to a ductile mechanism is all states. As the nitrogen content increases from 0.60 to 0.85%, the ultimate tensile strength of the steel decreases by 15% in the presence of a stress concentrator and remains substantially higher than the yield strength of the sheet steel without a stress concentrator.     

Deformability of niobium and tin bronze during compression

The deformability of Cu–14.5 wt % Sn–0.25 wt % Ti bronze and pure niobium (99.84%) is studied during compression tests. It is found that an increase in the strain rate or a decrease in the test temperature can improve the strength characteristics of both materials. The strength properties of bronze are more sensitive to a change in the temperature–rate deformation conditions.     

Structure and Mechanical Properties of Al–Ca–Mn–Fe–Zr–Sc Eutectic Aluminum Alloy after Warm Equal Channel Angular Pressing

Russian Journal of Non-Ferrous Metals - Recently developed multicomponent eutectic alloys based on Al–Ca are promising for practical application, since they are characterized by low density...