Our penetrator with the latest research developments and prospects tungsten alloy (b)

1.2 deformation strengthening research

Currently, the tensile strength of powder metallurgy method of preparing high density tungsten alloy (sintered) is generally up to 900 ~ 1000Mpa, elongation between 20% to 30%; while later after plastic deformation strengthening, its strength can greatly improve plasticity declined. After plastic deformation, can exceed the strength of tungsten alloy 1400MPa, the elongation can be maintained at about 10% [9].

Rolling, rotary forging, torsional deformation, hydrostatic extrusion deformation strengthening is to improve the strength of tungsten alloy material and ensure effective way certain toughness, but also the effective grain refinement [10]. Forging deformation is used to improve the strength of tungsten alloy technology, conventional deformation of about 15%. With the strength of tungsten alloy and increase the amount of deformation increases, the greater the amount of deformation of the tungsten particles larger deformation, and the deformation increases the degree of breakage will result in the transfer to the tungsten particles [11]. Rolling can also achieve greater deformation of the deformation and to ensure uniformity, and to make a large grain broken into small grains, and to obtain uniform distribution of the microstructure; rolling can increase the density and reduce the tungsten rod porosity, increase productivity and reduce manufacturing costs. However, due to the small amount of deformation and rolling a billet temperature and the final rolling temperature is higher, and surface oxidation is relatively serious pollution, high energy consumption, and therefore subject to a certain limit in actual production.

Rotary forging effects also increase the strength and armor-piercing tungsten alloy, after multi-pass swaging, the mechanical properties of strength and hardness of tungsten alloys have a more substantial increase than before swaging, but low elongation will. Large deformation makes spherical tungsten particles are elongated become fibrous tissue, can be greatly improved mechanical properties compared to the material. Quiet night extrusion technology is a hard plastic deformation of materials processing technology, mainly divided into cool liquid extrusion and hot hydrostatic extrusion, it is one of the most effective tungsten alloy deformation strengthening the current method, which can be obtained with a larger deformation strain and can greatly improve the characteristics of the material strength. At 3 under hydrostatic extrusion to compressive stress, not only can effectively prevent breakage and cracking of the material in the deformation of tungsten particles within the material is conducive to the healing of the original microscopic pores while being able to refine the microstructure conducive nearly net shape, improve efficiency, reduce costs and improve generation efficiency [12]. After the tungsten alloy using hydrostatic extrusion deformation strengthening and annealed, and breaking the material in the solution to form particles of tungsten high dislocation density cell structure in the material, its deformation after the tungsten particles were directional arrangement, cleavage fracture based. Hydrostatic extrusion deformation strengthening each to force uniform, material deformation process less prone to deformation defects, no heating, a large deformation, a 93W maximum deformation up to about 50% [13].
 

1.3 adiabatic shear Research

Adiabatic shear within the material or component of shear strain is highly concentrated narrow area that is under high strain rate loading conditions of material deformation and fracture of a special mechanism. Adiabatic shear deformation localization is widely present in the high-speed deformation process all kinds of metal, rock and polymer materials in the explosion suffered, penetration, high-speed collisions, wear high-speed cutting and high-speed strain rate loading, the increase in tungsten alloy material adiabatic shear properties to enhance the performance of tungsten alloy rod projectile penetration is currently one of the hotspots. Two of the five Institute, Chinese Academy of Mechanics, China University of Technology and Polytechnic University and other units Quote conducted a number of studies.

For half a century, the study of adiabatic shear deformation, mainly in three aspects: first, starting from the material constitutive relations, the establishment of adiabatic shear deformation localized buckling model to explore the adiabatic shear instability propagation law criterion and adiabatic shear bands; Second, microstructure, starting to explore the different components of the structure, microstructure features adiabatic shear band of tissue material within the organization as well as its nucleation and micro factors grew up; first Third, the use of computer simulation technology evolution of adiabatic shear band and should stand the strain and temperature field studies [14].

Wei Zhigang and other devices with a split Hopkinson pressure bar for oblique cylindrical specimen after pre-torsion impact test, not only observes the adiabatic shear band, while observing that if the maximum shear stress direction and orientation of the tungsten particles are consistent, then the failure is tungsten particles of brittle fracture, damage to the binder phase, tungsten - tungsten and tungsten interface separation - the result of both interfacial bonding separation of several damage mechanisms [15]. Hsu Shu-hua, etc. No pre-twisting and twisting tungsten alloy rod ballistic missile test and the residual microscopic tissue fragments were analyzed and found to reverse the pre-tungsten alloy with tungsten grain deformation direction close to the maximum shear stress direction, so projectile and target impact process in favor of adiabatic shear deformation and shear failure occurs. Observed from the remnants of warheads to adiabatic shear bands described in the pre-penetration bombs to reverse the process is easier than playing not to reverse the self-sharpening, which is pre-torsion rod projectile into the root causes of increased capacity [16]. Tan Chengwen, etc. In order to quantitatively evaluate the different materials on the sensitivity of the adiabatic shear deformation, can extend the use of adiabatic shear - adiabatic shear sensitive factor to characterize this difference, and to establish the corresponding experimental test system to solve the adiabatic shear quantitatively evaluate and test the sensitivity of the issue [17]. (To be continued)

References

[9] Zhang Baosheng, Kang Zhijun. Piercing characteristics of high-density tungsten alloy and its application [J]. China Tungsten Industry, 1999.14 (5-6) :178-185.

[10] Wilde, Yu Yang, Hu Lianxi, and so on. Advances in technology W-Ni-Fe based high-density tungsten alloy deformation strengthening [J]. Powder Metallurgy Technology, 2004,22 (5) :303-307.

[11] Shi Honggang, QI Zhi Wang, Xu Jie, et al. Affect the amount of deformation of tungsten alloy forging material properties Tak [J]. Ordnance Material Science and Engineering, 1998,21 (4) :3-6.

[12] Wang Yu change before David, the Qian Mei. Intensification of hydraulic extrusion technology [J]. Advanced materials and manufacturing technology. 1998, (5) :1-5, 25.

[13] Liu Zhiqiang, Yangguo Yi, Zhao Hongmei, et al. Analysis [J] high-density tungsten alloy hydrostatic extrusion tissue defect. Ordnance Material Science and Engineering, 2004,27 (4) :40-43.

[14] Tancheng Wen, WANG Fu-chi, Li Shukui. Adiabatic shear deformation localization research progress and development trend [J]. Ordnance Material Science and Engineering, 2003,26 (5) :62-67.

[15] Wei Zhigang, Hu SS, Lee pool. Experimental study of localized adiabatic shear deformation of powder sintered tungsten alloy [J]. Metal Journal, 1999,35 (8) :829-833.

[16] Hsu Shu-hua, Zhanggang Ming, Wang Xiaojun, et al. MICROMECHANICS pre-tungsten alloy rod projectile into reversing capability [J]. Explosion and Shock, 2000,20 (2): 143.

[17] Tancheng Wen, WANG Fu-chi, Liu Yuanhong, and so on. Adiabatic shear sensitivity study materials characterization and testing methods [J]. Beijing Institute of Technology, 2004,24 (5) :377-379.


Tungsten Manufacturer & Supplier: Chinatungsten Online - http://www.chinatungsten.com
Tel.: 86 592 5129696; Fax: 86 592 5129797
Email: sales@chinatungsten.com
Tungsten & Molybdenum Information Bank: http://i.chinatungsten.com
Tungsten News & Tungsten Prices, 3G Version: http://3g.chinatungsten.com
Molybdenum News & Molybdenum Price: http://news.molybdenum.com.cn

• < Prev
• Next >