Issue 76

H. Houri et alii, Fracture and Structural Integrity, 76 (2026) 238-264; DOI: 10.3221/IGF-ESIS.76.15

14000

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12000

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4000 Perssing Force (N) 6000 8000

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L= 20 mm L= 30 mm L= 40 mm L= 50 mm

L= 20 mm L= 30 mm L= 40 mm L= 50 mm

Perssing Force (N)

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2000

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0

0

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Time (s)

Time (s)

(a) φ =15° (b) φ =60° Figure 14: Variation of the pressing force for different channel lengths at φ = 15° and φ = 60° in the case of 2-ECAE using a 105° die. At the onset of extrusion, the pressing force begins to rise as the material comes into contact with the first outer corner of the second channel. At this stage, the initiation and subsequent growth of a shear band occur until the sample head fully passes through the first elbow, corresponding to the first plastic deformation zone. The curve then reaches a first plateau, which reflects the steady-state plastic flow as the material traverses this elbow. Upon crossing the second plastic deformation zone, a second plateau with slight undulations appears, attributable to the interaction between the plastic deformations generated by both elbows of the die. Effect of friction - Evolution of the equivalent plastic strain In this section, the effects of friction on the equivalent plastic strain distribution and the pressing force are analyzed for the optimized geometries of a 105° 2-ECAE die with φ = 15° and L = {20, 30, 40, 50 mm}. The interaction between the tool and the billet is modeled using Coulomb’s law of friction, and numerical simulations were conducted with four friction coefficients: f = {0, 0.1, 0.2, 0.3}.

(a) L=20mm)

(b) L=30mm

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