Plane stress fracture toughness of cryorolled 6082 Al alloy

Effect of crack path and high angle grain boundaries on fracture toughness and fatigue behaviour of cryorolled AA2219

“…Because the rolled sample exhibit dimensional limitations, the sample for testing satisfies the plane stress condition where a significant size of the plastic region is formed at the crack tip, as explored by Kumar et al 18 The fracture toughness in‐plane stress condition is calculated based on the load–displacement curve as per ASTM‐E1820 (2001) standards 12 . The load–displacement graphs are shown in Figure 4A, which demonstrates the critical crack growth by the evolution of secondary cracks from the grain boundaries and secondary precipitates 19 .…”

“…The specimen thickness and uncracked ligament size fulfil the critical plane stress condition. Hence, the obtained fracture toughness values can be considered as the critical plane stress fracture toughness ( J Ic ) 18 . The rolled AA2219 alloy has lesser fracture toughness than the alloy in the T87 condition.…”

“…Also, the 0.15‐mm exclusion line, 0.2‐mm offset line, 1.5‐mm exclusion line, Δ a min and Δ a limit are marked in the J ‐ R plot, which can be seen in Figures 5 and 6. Further, the conditional plane stress fracture toughness, J Q is validated for the following criteria to find out whether it is the J Ic values 18,20 …”

“…Substituting J Q and σ in Equation 1, it appears that the constraint values lie behind the values of the specimen thickness and uncracked ligament size. Hence, the obtained fracture toughness values can also be considered as the critical plane stress fracture toughness ( J Ic ) 18 . The values of critical plane stress fracture toughness determined from the J ‐ R curve are given in Table 3.…”

“…As final rolled thickness does not favour the minimum value for plane strain fracture condition, plane strain fracture toughness ( K JIc ) was determined from the J Ic values 4,21 . The plane strain fracture toughness of a thickness restricted rolled material is calculated by using the below mentioned Equation 3 as per the ASTM E1820‐13 standards 18 . The results of the fracture toughness values determined from the load–displacement curve, J ‐ R curve and J ‐ R ‐assisted conversion were briefed in Table 3.…”