Issue 76

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

geometry enhances strain distribution and reduces localized deformation, leading to a more moderate but stable hardening effect compared to the single-step die. Overall, these results highlight that the 1-ECAE Route A condition is most effective in maximizing hardness through continuous strain accumulation, while Route C and the 2-ECAE die configurations promote more balanced hardening behavior with reduced risk of overstraining or material relaxation. This demonstrates the crucial role of die geometry and processing route in tailoring the mechanical performance of polymers during ECAE.

N° Passe

1-ECAE (Route A)

1-ECAE (Route C)

2-ECAE (Route C)

(HB)

(HB)

(HB)

1 2 3 4 8

8.99 9.22 9.67

8.73 8.97 9.26

9.77

10.04 11.69 12.42 12.85

10.06 10.99 10.73 10.43

10.62 11.48

12 16

11.57 Table 8: Values of hardness average of polyamide samples obtained by 1-ECAE and 2-ECAE dies with a channel angle of 105° with route A and route C.

2

4

6

8

10

12

14

16

14

12

10

8

6

Hardness

4

2

0

Hardness

Hardness

Hardness

1-ECAE, Route A 1-ECAE, ROute C 2-ECAE, Route C

2

4

6

8

10

12

14

16

n° Passe

Figure 23: Evolution of hardness as a function of the number of passes at room temperature using a 1-ECAE and 2-ECAE die with a 105° channel angle, Routes A and C.

C ONCLUSION

T

his study was structured into two complementary parts combining numerical and experimental approaches. The first part focused on the numerical modeling and optimization of the geometric and processing parameters of the ECAE process, which provided the basis for the design and fabrication of ECAE dies with one and two channels. The second part was devoted to the experimental investigation of the material response, with particular emphasis on the evolution of curvature and hardness as indicators of deformation homogeneity and mechanical strengthening. Overall, the results highlight the crucial role of die geometry, corner angle, friction conditions, and processing routes in governing the deformation behavior of polyamide (PA) during equal channel angular extrusion (ECAE) using a 105° die. Based on these findings, the following conclusions can be drawn:

262