V. S. Yusupov

Effect of the quasi-continuous equal-channel angular pressing on the structure and functional properties of Ti–Ni-based shape-memory alloys

The effect of severe plastic deformation by equal-channel angular pressing (ECAP) under normal and quasi-continuous regimes on the structure and the mechanical and functional properties of a Ti–50.2 at % Ni shape-memory alloy (SMA) has been studied. ECAP was carried out at an angle of intersection of channels of 120° in the normal regime with heating between passes at 450°C for 20 passes and in the quasi-continuous regime at the temperature of 400°C for three, five, and seven passes. The hot screw rolling with subsequent annealing at 750°C for 30 min and cooling in water was used as a control treatment (CT). A mixed submicrocrystalline and nanosubgrained structure was formed. The increase in the number of passes from three to seven led to a decrease in the average size of structural elements from 115 ± 5 to 103 ± 5 nm and to an increase in the fraction of grains/subgrains having a size less than 100 nm. After ECAP (seven passes) and post-deformation annealing at the temperature of 400°C for 1 h, a completely recoverable strain was 9.5%; after normal ECAP, 7.2%; after CT, 4.0%.

Study of rolling in helical rolls by mathematical simulation with the DEFORM 3D software package

A mathematical model is developed and adapted for lengthwise rolling in special-profile helical rolls using the Deform 3D software package. The metal flow in rolling in helical rolls is studied. The state of stress in the deformation zone is analyzed, and the rolling force is calculated as a function of the technological rolling parameters and the geometrical characteristics of the helical rolls.

Mechanical activation of a hard magnetic Fe-Cr-Co alloy powder charge

The mechanical activation (MA) of a charge of a hard magnetic 22Kh15KT alloy is studied by wet and dry milling in a planetary mill in a medium of argon and ethyl alcohol with addition of surface-active materials and without them. It is shown that, upon dry MA, powder alloy components are alloyed with formation of two bcc solid solutions and, upon wet MA, charge particles are only intensely dispersed. Dispersion is developed at the highest degree in the first five minutes of MA.

Production of flat electrical steel with superlow magnetic losses

The influence of the chemical composition of steel (its Al, Si, and Sb content) on its texture and magnetic properties is studied, with a view to developing a production technology for high-alloy isotropic electrical steel (containing up to 3% Si) with superlow magnetic losses (P1.5/50 ≤ 2.70 W/kg for strip of rated thickness 0.50 mm and P1.5/50 ≤ 2.50 W/kg for rated thickness 0.35 mm) and a high degree of flatness (nonplanarity class 1 according to State Standard GOST 21427.2, with discrepancies no greater than 2 mm). Alloying with aluminum and antimony improves the texture of the final steel and hence greatly reduces the magnetic losses. The influence of cold rolling and recrystallization annealing of the flatness of the final strip is discussed.

Improving the production of electrowelded straight-seam pipe. Part 2

For 12 years, specialists from Baikov Institute of Metallurgy and Materials Science and PAO Severstal’ have been focused on introducing and improving production technology for smalland medium-diameter welded straight-seam pipe at PAO Severstal’. The results are summarized in the present work. The adjustment of the supporting and welding system is discussed. Welding by high-frequency currents permits more efficient edge heating of the pipe blanks and the production of high-quality weld seams.

Longitudinal rolling in helicoid rollers

A new method of sheet rolling in helicoid rollers is considered. In this approach, the roller barrel is formed by a helicoid with rounded projecting tips. The effectiveness of the rollers is demonstrated, and their geometric parameters are determined. Depending on the mutual orientation of the rollers’ helical barrel surfaces, rolling will produce linear hardened zones on the strip, at some angle to its longitudinal symmetry axis. Such nonuniform deformation increases the strength of the sheet, thanks to the formation of local hardened zones, without overall loss of strip plasticity.

Effect of copper additions on the mechanical properties of iron

The effect of copper alloying on the mechanical properties of iron is studied. Alloying of a model material (armco-iron) with 0.2–2.0% Cu is shown to increase the strength characteristics by a factor of 1.5–2.5 and to decrease the ductility by 8–60%.

Stampability Parameters of Automotive Steel

The methods of estimating the plasticity of sheet metals subjected to standard and nonstandard tests of their mechanical and technological properties have been analyzed and compared. A strain-hardening exponent and a coefficient of normal plastic anisotropy are found to adequately characterize the stampability of metals. It is demonstrated that a plastic stability criterion can be used to estimate the energy required for metal forming at the stage of uniform deformation.

Magnetic Hysteretic and Mechanical Properties of a 31Kh20K3M Alloy with an Increased Carbon Content

An Fe–31Cr–20Co–3Mo (31Kh20K3M) alloy containing 0.09 wt % C, which is almost twice as much as its maximum content according to GOST 24897–81, has been studied to verify the influence of the carbon content on the magnetic hysteretic properties of hard magnetic high-chromium Fe–Cr–Co alloys. The optimal heat treatment, including thermomagnetic treatment, results in the average values of residual magnetic induction Br = 0.96 T and coercive force HcB = 63 kA/m and the maximum energy product (BH)max = 29 kJ/m3. Some heat treatment regimes give Br = 1.03 T, HcB = 72 kA/m, and (BH)max = 31 kJ/m3. In addition, for isotropic alloy samples, the following average values are obtained: Br = 0.71 T, HcB = 56 kA/m, and (BH)max = 15 kJ/m3. These magnetic hysteretic properties of the 31Kh20K3M alloy with an increased carbon content are similar to those of a powder 30Kh21K3M alloy with the minimum carbon content.

Magnetic Hysteresis and Mechanical Properties of Hard Magnetic Fe–27Cr–15Co–2Mo–Si–Ti–V Alloy

Magnetic hysteresis and mechanical properties of a hard magnetic alloy Fe–27Cr–15Co–2Mo–V–Si–Ti in an isotropic and anisotropic state are investigated with the help of the method of design of experiments for the purpose of developing a new hard magnetic material with increased values of residual induction Br (isotropic state) and coercive force HcB (anisotropic state). Optimization of the modes of heat treatment is performed by the creation of central composite design 23 + star points. Statistical analysis of the data obtained makes it possible to ascertain the standard Pareto charts for Br, HcB, and (BH)max values for isotropic and anisotropic alloys. Nonlinear regression equations for dependences of Br, HcB, and (BH)max on variation factors are obtained, on the basis of which optimal regimes of heat treatment are determined. Magnetic hysteresis properties of Fe–27Cr–15Co–2Mo–V–Si–Ti alloy are enhanced significantly after an optimal heat treatment. As a result, a new hard magnetic material on the basis of the Fe–27Cr–15Co system is developed. In the anisotropic state, the values of residual induction, coercive force, and maximum energy product are Br > 1 T, HcB > 50 kA/m, and (BH)max > 24 kJ/m3, respectively, whereas in the isotropic alloy they are Br ~ 0.8 T, HcB ~ 40 kA/m, and (BH)max > 11.5 kJ/m3. Analysis of magnetic properties of specimens from the produced pilot batch of anisotropic Fe–27Cr–15Co–2Mo–V–Si–Ti magnets in the number of 51 pieces shows that the yield of magnets with HcB > 45 kA/m is 100% and with HcB > 50 kA/m is 83%.