PSI - Issue 83

Sze Pei Tan et al. / Procedia Structural Integrity 83 (2026) 28–40

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Fig. 5. Fatigue crack propagation testing

4. Results and Discussion This section discusses the results from tensile test, fatigue life test, and fatigue crack propagation testing. 4.1. Tensile testing The results from the tensile testing for both heat-treated and non-treated specimens are presented here. The influence of peak hardening on the tensile test result and the behavior is discussed correspondingly. Table 3 presents the overall tensile test results for both heat-treated and non-treated specimens. It was observed that the heat-treated (T6) specimens show an improvement in ultimate tensile strength (UTS), yield strength, modulus of elasticity and strain. Compared to the as-built specimens. In this study, the heat-treated specimens are stress relieved prior to any testing and analysis. It is reported from literature, the UTS for heat-treated decreased after SHT as presented in Table 2. However, the incremental of the UTS is not as severe as the strain where the as-built only recorded elongation of 4.3 % compared to heat-treated at 14.7 %.

Table 3. Overall tensile test results compared with previous study

Specimen

Yield Strength, 0.2 % offset (MPa)

Modulus Strength (GPa)

Ultimate Strength (MPa)

Strain, (%)

Experiment

As-built

162.5 242.0

63.5 68.9

280.4 310.2

4.3

Heat-treated

14.7

As-built

265.0 231.0

81.0 80.0

330.0 292.0

1.4 3.9

Brooks & Choudhury (2002) [25]

T6