PSI - Issue 81

Serhiy Fedak et al. / Procedia Structural Integrity 81 (2026) 305–309

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papers by Yasniy and Hlado (2002), Yasniy et al. (2004), leading to a model where AMg6 can be treated as a composite material with these dispersoids acting as fibers that was described by Karpynos et al (1985). Objective of the research is to characterize the deformation behaviors of the AMg6 alloy under uniaxial tension, specifically focusing on the mechanisms of jump strain hardening. The identified patterns are supposed to be integrated into a predictive model for generating the alloy's deformation diagram, leveraging data from a histogram of dispersoid distribution within the matrix.

Nomenclature  p (  i ) stress of dispersiod fracture  st

stress of the beginning of the jumping process stress increment between jump-like deformation increments

 i  e i

strain increment between jump-like deformation increments  (  i ) deformation increment during the fracture of dispersoids Eʹ i proportionality coefficient that corresponds to the region between jump-like increments of deformation E Young's modulus

2. Experimental study The study conducts an analysis of how the behavior of deformation shifts within the stress intervals that occur between sudden jumps in strain. The dependencies derived from this analysis are proposed for use in a method designed to forecast the overall deformation profile of AMg6 alloy. The mechanical properties of smooth cylindrical AMg6 alloy specimens were investigated using an STM-100 servo-hydraulic testing machine at a constant temperature of 293 K by Yasniy and Halushchak (1998). The tensile tests were carried out at a fixed rate of increasing conventional static stress 1.6 MPa/s. When the AMg6 alloy is subjected to tension under mild loading conditions, the material exhibits intermittent flow or ‘ jump like deformation ’ . This phenomenon is vi sually represented as distinct ‘ steps ’ on the deformation diagram  (  i ) (Fig. 1).

σ

σ р (α і+1 )

σ р (α і )

σ st

Δσ і

σ 02

Δε(α і )

Δεе і

ε

Fig. 1. Diagram of deformation of AMg6 alloy under quasi-static tension in the mild type loading conditions.

As the stress level  p (  i ) increases, the magnitude of the jump deformation (represented by the width of the ‘ step ’ on the tensile diagram) also increases. The region characterized by this discontinuous increase in deformation under mild loading conditions is defined by several parameters: the stress threshold  st at which jump begins the stress increment between successive jumps  і , the relevant proportionality coefficients within these areas і Е  , and the specific jump deformation magnitude  (  i ) at the corresponding stress  p (  i ). The index і refers to the specific class of dispersoids that fracture during the elastic deformation phase of the matrix. Consequently, the AMg6 aluminum alloy can be modelled as a composite material comprising a viscous matrix reinforced with brittle inclusions as described by Fedak (2003), Yasniy et al. (2001). In this framework, the internal dispersoids act as barriers to dislocation movement, causing dislocation clouds to accumulate around them. Once a specific load threshold is reached, these brittle inclusions fracture, and the stored dislocation energy is released as the cloud disperses. This combined process of dispersoid fracture and dislocation dispersal manifests as a sudden surge in plastic deformation – a ‘ deformation breakdown ’ . At the micro