Structural and mechanical embrittlement of titanium alloys under stress concentration

Purpose. Existing methods for assessing the effect of embrittlement of titanium alloys are associated with compulsory costly experiments. For settlement prediction of the critical parameters of the mechanical stability and strength under conditions of stress concentration is necessary to develop principles for assessing the effect of embrittlement of structural titanium alloys based on the concept of mechanical stability. Methodology. On the basis of our experimental data set patterns of change in the structural quality and the model of structural and mechanical embrittlement of structural titanium alloys. Findings. On the basis of previously established differences between the behaviors of mechanical properties of structural titanium alloys introduced the concept of species transitions for these alloys. First obtained by modeling patterns of structural and mechanical embrittlement of titanium alloys, which allowed us to develop an algorithm of calculation of the critical parameters of the mechanical stability Kmsc, strength 0 0 ,2c, strength 0 2c at the degree of deformation of ec ? 2% brittleness temperature Tc as a result of a uniaxial tensile test of smooth specimens. Originality. It was found that the model patterns of structural and mechanical embrittlement of structural titanium alloys are identical to those laws for structural steels and depend only on the structural state of the alloy, the geometry of a stress concentrator and conditions of stress-strain state of the species and the transition. Practical value. Using the developed methodology for assessing the effect of embrittlement possible to determine the critical parameters of the mechanical stability and strength of the structural fragility temperature Tc titanium alloy containing a stress concentrator and a certain geometry is in these conditions, the stress-strain state. It is sufficient to know the values of yield strength 0 0 ,2 and strength <72 at the critical degree of deformation of ec ? 2%, determined according to the results of tests on the sample of smooth static uniaxial tensile test at room temperature, the temperature dependencies of these characteristics, as well as information about the species of the alloy to transition. To stress concentrators and loading conditions other than the model, must also know the laws of structural and mechanical embrittlement, which can be determined by test results of only one sample in these conditions for each species of transition.