Theoretical and Statistical Basis for Stability of Titanium Alloy Ti – 6% Al – 4% V Semiproduct Mechanical Properties

Increasing the Stability of Mechanical Properties of Semifinished Products from Ti–6Al–4V Alloys by Correcting the Alloying Range and Annealing Modes

“…However, the average values and actual and statistical (3σ) alloying ranges for aluminum and oxygen are shifted toward the upper limit of the tolerance band. As a result, the structural equivalent of aluminum for some semifinished products reaches values exceeding the critical level of 9%, above which, due to the formation of titanium aluminide, a significant decrease in plastic properties is registered with a simultaneous increase in strength [10]. The statistical ranges (3σ intervals) of the total alloying with αand β-stabilizers, equivalent to aluminum and molybdenum, are 6S ≈ 1.5%-3.5%.…”

“…Depending on the chemical composition, type of semifinished product, heat treatment mode, and structure, the mechanical properties of Ti-6A1-4V alloys can vary over a fairly wide range, not only in terms of the volume of the billet but also in a batch of similar semifinished products and in different batches [9][10][11][12]. The spread of values of the ultimate strength of VT6 alloys after annealing, admitted by the RD, is 100-200 MPa (Table 2).…”

“…In this situation, for the study of each of the stages, it is advisable to use statistical methods and identify significant factors of the influence on the final properties of the product, which enables to adjust production processes and improve the quality of titanium semifinished products. Based on the long-term statistical studies of the results of industrial control and production tests, performed by the authors, variations in the mechanical properties of semifinished products from titanium alloys can be caused by fluctuations not only in the modes of deformation and heat treatment but also in the grade composition [10,11,[14][15][16][17]. The Present Work Aims to develop recommendations aimed at improving the quality of semifinished products from various modifications of the titanium alloy Ti-6A1-4V based on assessing the stability of their chemical composition, heat treatment modes, and a set of mechanical properties.…”

The Study of the Complex Mechanical Properties of Rolled Bars of VT6 Alloy as a Function of Chemical Composition and Structure Type

“…ВВЕДЕНИЕ К основным требованиям, предъявляемым к титановым сплавам ответственного назначения, следует отнести, прежде всего, обеспечение высокого уровня механических свойств, их стабильности и воспроизводимости. Вместе с тем, в промышленных полуфабрикатах из титановых сплавов, даже изготовленных по одной технологии, наблюдается большой разброс механических свойств [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Так, например, в прутках и поковках из сплава ВТ6 колебания поперечного сужения могут достигать 20-30%, а предела прочности -150-200 МПа [3,[7][8][9][10].…”

“…Вместе с тем, в промышленных полуфабрикатах из титановых сплавов, даже изготовленных по одной технологии, наблюдается большой разброс механических свойств [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Так, например, в прутках и поковках из сплава ВТ6 колебания поперечного сужения могут достигать 20-30%, а предела прочности -150-200 МПа [3,[7][8][9][10]. Такая нестабильность свойств может быть связана со многими случайными факторами, к которым следует отнести, прежде всего, колебания легирующих элементов и примесей в нормативных пределах.…”