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Failure Analysis Case Studies II Episode 5

Tham khảo tài liệu 'failure analysis case studies ii episode 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 128 8 Brittle fracture 9 Brittle fracture 1 in. 25 mm in centre ductile 10 Brittle fracture into drainhole 1 in. 25 mm ductile then brittle 11 Brittle fracture 12 Brittle fracture 13 Ductile Generally even where full 45 shear fracture was evident the reduction of area accompanying the fracture was small. An inspection of the port bilge keel remaining on the aft section of the ship revealed cracks in two weld details similar to the bilge keel initiation site on the port side. Extraction of these samples was requested. The heating coils used to keep the oil in the tanks at 140 F 60 C are evident in many of the figures. It must be pointed out however that the initiation site in the port bilge keel would have been surrounded by sea-water and as such could be considered to be at the water temperature of 0.7 C. Two meetings were held between the interested parties on 16 and 17 April 1979 respectively. At the first it was agreed by all concerned that TWI should carry out any tests required to ascertain the reasons behind the failure. At the second meeting the five test samples required for this investigation selected by the DoT and TWI representatives during their inspections were described to the interested parties who agreed to the extraction of these samples and their shipment to the TWI. Details of the samples required were left with the ship owners and a Lloyds representative was appointed to supervise the extraction of the samples. The positions of the required test samples were then marked on the vessel by the DoT and TWI representatives. 3. DISCUSSION OF THE RESULTS OF THE FAILURE INVESTIGATION 3.1. ỉntroduclion Three of the samples identified during the dry dock inspection of the vessel described above contained initiation sites. At the start of the mechanical and metallurgical test programme described in 1 each of these samples were treated with equal importance. However as the test programme developed various aspects became clearer and the port bilge keel .