Mechanical Behavior of Nanostructured and Ultrafine-Grained Metal Alloy under Intensive Dynamic Loading

2020

Metals

Self Cite

The present study investigates the effect of stress triaxiality on mechanical behavior and fracture of Ti-5Al-2.5Sn alloy in a practical relevant strain rate range from 0.1 to 1000 s−1. Tensile tests were carried out on flat smoothed and notched specimens using an Instron VHS 40/50-20 servo-hydraulic test machine. High-speed video registration was conducted by Phantom 711 Camera. Strain fields on the specimen gauge area were investigated by the digital image correlation method (DIC). The fracture surface relief was studied using digital microscope Keyence VHX-600D. Stress and strain fields during testing of the Ti-5Al-2.5Sn alloy were analyzed by the numerical simulation method. The evolution of strain fields at the investigated loading condition indicates that large plastic deformation occurs in localization bands. The alloy undergoes fracture governing by damage nucleation, growth, and coalescence in the localized plastic strain bands oriented along the maximum shear stresses. Results confirm that the fracture of near alpha titanium alloys has ductile behavior at strain rates from 0.1 to 1000 s−1, stress triaxiality parameter 0.33 < η < 0.6, and temperature close to 295 K.

Section: Numerical Simulation Of Plastic Flow and Damage Evolutionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fracture of Titanium Alloys at High Strain Rates and under Stress Triaxiality

2020

Metals

Self Cite

“…The mechanical behavior of HCP alloys under quasistatic and dynamic loading at temperatures T /T m less than 0.5 is determined by dislocation mechanisms and twinning [25][26][27][28][29]. Authors used modifications of the constitutive equations developed in the framework of the micro-dynamical approach and taking into account the thermally activated dislocation mechanisms [15][16][17][30][31][32].…”

Section: Computational Modelmentioning

confidence: 99%

“…Therefore, the optimization of strength and ductility requires a profound knowledge of volume fraction and distribution of ultra-fine grains and coarse grain in multi-modal alloys. Research of the influence of the grain structure on the strength and ductility of the alloys under cyclic loadings, dynamic loadings, quasistatic loadings are carried out using experimental methods and by computer simulation [14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

Failure Mechanisms of Alloys with a Bimodal Graine Size Distribution

Springer Tracts in Mechanical Engineering

2020

Self Cite

A multi-scale computational approach was used for the investigation of a high strain rate deformation and fracture of magnesium and titanium alloys with a bimodal distribution of grain sizes under dynamic loading. The processes of inelastic deformation and damage of titanium alloys were investigated at the mesoscale level by the numerical simulation method. It was shown that localization of plastic deformation under tension at high strain rates depends on grain size distribution. The critical fracture stress of alloys depends on relative volumes of coarse grains in representative volume. Microcracks nucleation at quasi-static and dynamic loading is associated with strain localization in ultra-fine grained partial volumes. Microcracks arise in the vicinity of coarse and ultrafine grains boundaries. It is revealed that the occurrence of a bimodal grain size distributions causes increased ductility, but decreased tensile strength of UFG alloys. The increase in fine precipitation concentration results not only strengthening but also an increase in ductility of UFG alloys with bimodal grain size distribution.

“…In Ref. [24][25][26][27], numerical values of model parameters of UFG alloys are discussed. Used numerical method is discussed in [24][25].…”

mentioning

confidence: 99%

Mechanical Behavior of Light Alloys with Bimodal Grain Size Distribution

2015

AMM

Deformation and damage at the meso-scale level in representative volumes (RVE) of light ultrafine grained (UFG) alloys with distribution of grain size were simulated in wide loading conditions. The computational models of RVE were developed using the data of structure researches aluminum and magnesium UFG alloys on meso-, micro -, and nanoscale levels. The critical fracture stress on meso-scale level depends not only probabilistic of grain size distribution in RVE but relative volumes of coarse grains. Microcracks nucleation is associated with strain localization in UFG partial volumes in alloys with bimodal grain size distribution. Microcracks branch in the vicinity of coarse and ultrafine grains boundaries. It is revealed that the occurrence of bimodal grain size distributions causes the increasing of UFG alloys ductility, but decreasing of the tensile strength. The distribution the shear stress and the local particle velocity takes place at mesoscale level under dynamic loading of UFG alloys with bimodal grain size. The increasing of fine precipitations concentration not only causes the hardening but increasing of ductility of UFG alloys with bimodal grain size distribution.