372595868

JPRS-UMS-92-003 16 March 1992

ANALYSIS, TESTING

Ukrainian Academy of Sciences, Kiev, and Central Sci-entific Research Institute of Stmctural Materials, St. Petersburg]

UDC 620.172.254

[Abstract] Available experimental data on the strength and ductility characteristics of alloyed structural steels under straining do not cover high straining rates; conse-quently, the results of mechanical tensile tests of second-ary-hardenable chromium-nickel-molybdenum Steel heat-treated for various static strength levels are pre-sented. Dynamie tests at plastic deformation rates of up to 5 x 10⁴ s^_1 were conducted in a 77-523K temperaturę rangę while static tests were carried out at a tensile ratę of 2 mm/min in an Instron machinę. The dcpendencc of the strength and ductility characteristics of Cr-Ni-Mo Steel heat-treated for various strength levels on the straining ratę and temperaturę is investigated and plotted for various samples. The results are consistent with the dislocation model of plastic metal flow and may be divided into three ranges corresponding to different straining rates. An improvement in strength and ductility with the straining ratę is demonstrated. The find-ings contradict the hypothesis of the equivalent effect of temperaturę drops and straining ratę inereases on the mechanical characteristics of metals. The conclusion is drawn that Cr-Ni-Mo Steel is highly reliable for use under such operating conditions. Figures 3; references 9.

Effect of Artificial Surface Defects on Steel Slab Failure During Contact Loading by Explosive Layer Detonation

927D0062E Kiev PROBLEMY PROCHNOSTI in Russian No 9(267), Sep 91 pp 11-14

[Article by A.S. Ispatyev, Special Design Office of Hydraulic Impulse Technology at the Siberian Department of the USSR Academy of Sciences, Novosibirsk]

UDC 620.192.7+621.7.044.2

[Abstract] The use of various explosion methods for cropping oversize metal items and their shorteomings are discussed and the effect of surface defects on the character of Steel slab failure is investigatcd in order to produce a feasibility study for inereasing the produc-tivity of oversize item cropping and reduce the specific consumption of explosives (W). The effect of noncon-tinuous surface defects on the failure characteristics is considered for both mechanically and explosion-induced defects. The failure of 75 and 150 mm-thick Steel St.3 slabs with an artificial defect representing a set of individually drilled holes by a surface explosion charge is examincd. A two-stage failure mechanism is suggested and corroborated. The results show that it is possible to substantially lower the specific explosive charge consumption by selecting the artificial defect shape (e.g., a set of shallow drilled holes); the explosivc charge shape is optimized: the specific consumption of ammonite 6ZhV is 15 and 19 g/cm for the 75 mm-thick slabs with different defect sizes. Figures i; tables 1; references 3.

Estimation of Strained State of Base Slab During Explosion Welding

927D0062D Kiev PROBLEMY PROCHNOSTI in Russian No 9(267), Sep 91 pp 9-11

[Article by V.G. Resinov, S.G. Tsybochkin, Yu.A. Konon, Scientific Production Association of the Altay Scientific Research Institute of Mechanical Engineering, Bamaul]

UDC 539.4

[Abstract] The need to determine the strain and veloci-ties of slabs used in exp!osion welding, particularly in the case of oblique collision, in order to analyze the taut strained State of the base slab is identified; the processes of obliquc collision of the projectile slab with the elastic base slab and explosion strengthening are generally sim-ulated by a moving surface load locally distributed in a certain neighborhood of the point of contact and applied uniformly along a linę on a surface. The boundary value problem under the conditions of planar strain is solved. The longitudinal strain on the s!ab’s free surface is measured experimentally. The estimates make it possible to predict the behavior of materials sensitive to the straining ratę under explosion welding loading conditions. The experimental results are found to be consistent with theoretical data. Figures 2; references 5.

Estimation of Stresses and Strain During Explosion Welding

927D0062C Kiev PROBLEMY PROCHNOSTI in Russian No 9(267), Sep 91 pp 7-9

[Article by V.P. Bartenev, G.V. Stepanov, Scientific Production Association of the Altay Scientific Research Institute of Mechanical Engineering, Barnaul, and Strength Problems Institute at the Ukrainian Academy of Sciences, Kiev]

UDC 539.4

[Abstract] The inability of existing methods to analyze the taut strained State (NDS) after the compression wave reflection from the slab end and the dynamie loading during explosion welding which often leads to intense strain and failure near the ends of welded slabs is discussed and the methods developed earlier by the authors {Problemy prochnosti No. 9, 1988) is used to determine the dynamie field of the tensile stresses and shearing strain developing during explosion welding. The oblique collision of slabs is simulated by loading a layer of acoustic materiał of finite thickness and length moving at a given velocity by a locally distributed supcrficial load defmed by an expansion into a double Fourier series. The boundary value problem is solved by