Sample records for alloy-vt22

  1. Influence of Tensile Stresses on α+β – Titanium Alloy VT22 Corrosion Resistance in Marine Environment

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    Yu. A. Puchkov


    Full Text Available Tensile stresses and hydrogen render strong influence on the titanic alloys propensity for delayed fracture. The protective film serves аs a barrier for penetration in hydrogen alloy. Therefore to study the stress effect on its structure and protective properties is of significant interest.The aim of this work is to research the tensile stress influence on the passivation, indexes of corrosion, protective film structure and reveal reasons for promoting hydrogenation and emerging propensity for delayed fracture of titanium alloy VТ22 in the marine air atmosphere.The fulfillеd research has shown that:- there is а tendency to reduce the passivation abilities of the alloy VТ22 in synthetic marine water (3 % solution of NaCl with increasing tensile stresses up to 1170 МPа, namely to reduce the potential of free corrosion and the rate of its сhange, thus the alloy remains absolutely (rather resistant;- the protective film consists of a titanium hydroxide layer under which there is the titanium oxide layer adjoining to the alloy, basically providing the corrosion protection.- the factors providing hydrogenation of titanium alloys and formation in their surface zone fragile hydrides, causing the appearing propensity for delayed fracture, alongside with tensile stresses are:- substances promoting chemisorbtion of hydrogen available in the alloy and on its surface;- the cathodic polarization caused by the coupling;- the presence of the structural defects promoting the formation of pitting and local аcidifying of the environment surrounding the alloy.

  2. Influence of grinding on service properties of VT-22 powder applied in additive technologies (United States)

    Zakharov, M. N.; Rybalko, O. F.; Romanova, O. V.; Gelchinskiy, B. R.; Il’inykh, S. A.; Krashaninin, V. A.


    Powder of titanium alloy (VT-22) produced by plasma-spraying was subjected to grinding to obtain powder with size less 100 microns. These powders were sprayed by plasma unit using two types of gases, namely, air and air with methane (spraying in water and sputtering of coating on steel support). Influence of grinding time on yield of powder of required fraction was studied. Morphology and phase composition of the grinded powder and plasma sprayed one were under investigation. In the result of experiments, it appears that the grinding time genuinely influences the chemical and phase compositions, but there is no effect on physical-processing properties. For powders after plasma spraying some changes of non-metal elements content were detected by chemical analysis. Using gaseous mixture of air and methane in plasma spraying unit leads to formation of a new phase in the powder according X-ray diffraction data.

  3. STA heat treatment of beta-titanium alloys after various thermomechanical processing

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    Ivasishin, O.M.; Markovsky, P.E.; Teliovich, R.V.; Matviychuk, Yu.V. [AN Ukrainskoj SSR, Kiev (Ukraine). Inst. Fiziki Metallov


    Commercial beta-titanium alloys are promising material for a wide range of applications due to essentially high strength/density ratio, sufficient fatigue performance and crack propagation resistance. Present work was aimed at systematical study the microstructure and mechanical properties of two commercial beta-titanium alloys VT22 and TIMETAL {sup trademark} -LCB in STA condition produced by special heat treatment, comprising from rapid heating into a single-phase beta field and subsequent aging, depending on previous thermomechanical processing employed. Three types of such a processing were studied: hot deformation at temperatures of alpha+beta field, hot deformation in single-phase beta field and cold deformation of as-quenched metastable beta phase. Solid solutionizing by rapid heating has proved to be efficient in receiving fine-grained beta microstructure with average grain size, which varies from 50 {mu}m to 12 {mu}m depending on initial microstructure. Such treatment allowed to obtain on subsequent aging yield strengths up to 1470 MPa while maintaining sufficient ductility. (orig.)