Экспериментальное и теоретическое исследование высокоскоростного проникания длинных стержневых ударников в песок

Results of computations with the use of improved modified Alekseevskii-Tate theory (IMATT) are compared to experimental data on high-velocity penetration of long rod projectiles into sand in the impact velocity range of V0=0.5-3.5 km/s. Projectiles were made of three different metals: M1 copper, WNZh tungsten heavy alloy and 30KhGSA steel. The value of hardening coefficient k in the linear dependence of the projectile material yield on pressure could be determined using IMATT and experimental data on dependence of differential penetration coefficient K on the penetration velocity. At penetration in regime of the hydrodynamic erosion of projectile, differential penetration coefficient K could be approximated just by dependence on the ratio of the impact velocity of penetration to the value of the critical velocity, above which the projectile deforms plastically during penetration. The values of the critical velocity may differ for specific projectile material properties as well as the density and the humidity of sand.

Comparative studies of the constitutive models for tungsten heavy alloy (95W-3.5Ni-1.5Fe) at high strain rates

The plastic behaviors’ description of a tungsten heavy alloy (95W-3.5Ni-1.5Fe) at temperatures of 298–773 K and strain rates of 0.001–11,000 s−1 is systematically studied based on four constitutive models, that is, Zerilli-Armstrong model, modified Zerilli-Armstrong model, Mechanical Threshold Stress model, and modified Mechanical Threshold Stress model. The quasi-static compression experiments using an electronic universal testing machine and the dynamic compression experiments using a split Hopkinson pressure bar apparatus are employed to obtain the true stress–strain curves at a total of three temperatures (298 K, 573 K, and 773 K) and a wide range of strain rates (0.001–11,000 s−1). The parameters of the four constitutive models are obtained by the above fundamental experimental data and Grey Wolf Optimizer. The correlation coefficient and average absolute relative error are used to evaluate the predicted performance of these models. Modified Mechanical Threshold Stress model is found to have the highest predicted performance in describing the flow stress of the 95W-3.5Ni-1.5Fe alloy. Eventually, two compression experiments whose loading conditions are not in the fundamental experiments are conducted to validate the four models.

Preliminary Study of the Rhenium Addition on the Structure and Mechanical Properties of Tungsten Heavy Alloy

The results of structure and mechanical property investigations of tungsten heavy alloy (THA) with small additions of rhenium powder are presented. The material for the study was prepared using liquid phase sintering (LPS) of mixed and compacted powders in a hydrogen atmosphere. From the specimens, the samples for mechanical testing and structure investigations were prepared. It follows from the results of the microstructure observations and mechanical studies, that the addition of rhenium led to tungsten grain size decreasing and influencing the mechanical properties of W-Ni-Fe-Co base heavy alloy.

The Effect of Cold Swaging of Tungsten Heavy Alloy with the Composition W91-6Ni-3Co on the Mechanical Properties

The paper presents the results of studies on the effects of heat treatment and cold-work parameters on the mechanical properties and microstructure of the tungsten heavy alloy (WHA) with the composition W91-6Ni-3Co. Tungsten heavy alloy (WHA) is used in conditions where strength, high density, and weight are required. The material for testing as rod-shaped samples was produced by the method of powder metallurgy and sintering with the participation of the liquid phase and then subjected to heat treatment and cold swaging. The study compares the effect of degree deformation on the strength, hardness, microhardness, and microstructure of WHA rods. The conducted tests showed that heat treatment and cold-work allowed to gradually increase the strength parameters, i.e., tensile strength , yield strength , elongation ε, hardness, and microhardness. These processes made it possible to increase the tensile strength by over 800 MPa (from the initial 600 MPa after sintering to the final value of over 1470 MPa after heat treatment with cold swaging deformation with reduction of 30%) and the hardness from 32 to 46 HRC.

Effect of Heat Treatment Process and Composition on Deformation and Damage Behavior of WHA under Detonation Loading

The excellent material properties of tungsten heavy alloy (WHA) make it widely used in the military field. When used as killing elements of weapons, its dynamic mechanical properties under detonation loading directly determine the damage effect of weapons, which makes the research on its mechanical behaviors under high pressure and high strain rate loads such as detonation loading of great significance. In this paper, several WHAs with different compositions and processes are selected, and the mechanical properties and deformation and damage behavior under static explosion test are analyzed by combining macro and micro study, so as to provide guidance for the subsequent optimization of the performance design of WHA.

Mechanical and Fatigue Properties of Tungsten Heavy Alloy Prepared by RF-Plasma

Tungsten heavy alloy (WHA) of W-Ni composition was deposited from a blend of standard thermal spray powders using radio frequency inductively coupled plasma torch (RF-ICP) in a protective atmosphere. The deposit (RF WHA) contained a fully developed WHA structure; i.e.; spherical W particles embedded in a Ni-rich matrix. The bending tensile strength Rm; bending yield strength Rp;0.2; and elastic modulus of the deposit were compared with two W-Ni-Co references fabricated by powder metallurgy (PM WHA) via sintered and quenched (PMSQ); and forged and annealed (PM-FA). While the RF deposit properties are comparable with the PM-SQ reference; the PMFA exhibited higher mechanical properties. The deposit showed very limited ductility A < 3%. The fatigue crack growth rate in the deposit measured in bending (R < -1) was comparable to the PM-SQ reference material in the near-threshold region whereas the forged PM-FA had significantly better fatigue performance. In the near-threshold fatigue regime; the crack growth took place in the Ni-rich matrix. In the Paris regime; the similar fracture mode was observed; with the exception of PM-SQ; where the tungsten particles fracture contributed significantly. The static failure was exclusively trans-particle in RF WHA; while both PM WHAs failed by a mix of ductile matrix failure and trans-particle cleavage fracture. The fracture toughness of the deposit was significantly lower than the references. These early results indicate that RF-plasma spray is a suitable and efficient manufacturing method for production of WHA materials; however with limited mechanical properties in some aspects.