Marks Question 4 (20 Marks Total) A crack is detected next to the heat affected zone (HAZ) of a weld as shown in Fig. 04

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Marks Question 4 20 Marks Total A Crack Is Detected Next To The Heat Affected Zone Haz Of A Weld As Shown In Fig 04 1 (54.46 KiB) Viewed 22 times

Marks Question 4 (20 Marks Total) A crack is detected next to the heat affected zone (HAZ) of a weld as shown in Fig. 04(a). The 45" interface between the weld and the HAZ has a lower strength than the surrounding material. Both weld and HAZ may be represented as Ramberg Osgood materials with = 600 MPa, 6 = 0.003, a = 0.1, n = 13. The fracture toughness value Jd for the HAZ is 0.12 MPamat room temperature. Fracture along the weld/HAZ interface is controlled by the attainment of a critical (hoop) stress at a critical distance, with values 1500 MPa and 510 um, respectively. (a) If the crack is loaded under Model conditions determine whether the crack will grow into the HAZ or along the interface at room temperature. You may make use of the HRR distribution provided in Fig. 04(b). The value of I, in the HRR distribution is 4.4 for n = 13. (b) If the temperature falls to -100 C the yield strength of the HAZ increases to 650 MPa and the fracture toughness falls to 0.05 MPam All other material properties are unchanged. Determine the minimum interface strength to ensure that the crack grows into the HAZ rather than along the interface at this temperature. 10 10 16 n 13 2 96 2 Weld ö Heat affected zone (HAZ) " 45 16 1 10 1 Interface 6. IT12 8 (a) (b) Figure Q4