Tham khảo tài liệu 'volume 17 - nondestructive evaluation and quality control part 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Grade 000 penetrameter for materials Group Mg Grade 00 penetrameter for materials Group Al Grade 0 penetrameter for materials Group Ti Grade 1 penetrameter for materials Group 1 Grade 2 penetrameter for materials Group 2 Grade 3 penetrameter for materials Group 3 Grade 4 penetrameter for materials Group 4 Grade 5 penetrameter for materials Group 5 Detail of notch Fig. 55 Identification system of ASTM penetrameter material composition grades The circular plaque design is larger than the rectangular plaque design and is specified for plaque thicknesses of to 4 mm to in. . Figure 54 b shows the circular design specified by ASTM and ASME for plaque-type penetrameters with thicknesses of mm in. or more. Various degrees of image quality can be measured by using plaque-type penetrameters of different thicknesses. Sensitivity is usually expressed in terms of penetrameter thickness as a percentage of testpiece and resolution is determined by the smallest hole size visible in the radiograph. For example an image-quality level of 2-2T indicates that the thickness of the penetrameter equals 2 of section thickness and the 2T hole is visible. If image quality of 1-1T were required a radiograph would be acceptable if the outline of a 1 penetrameter were distinguishable. Alternatively image quality can be expressed as a percentage only. In the ASTM or ASME systems the equivalent sensitivity in percent is based on visibility of the 2T hole. Table 9 lists equivalent sensitivities for various standard image-quality levels. Table 9 Equivalent sensitivities of various standard ASTM or ASME sensitivity levels Equivalent sensitivity is a percentage equivalent for penetrameter thickness in which 2T is the smallest distinguishable hole size. For example 1-1T is equivalent to . Image-quality level Penetrameter thickness of testpiece thickness Smallest visible hole size Equivalent sensitivity 1-1T 1 1T 1-2T 1 2T 2-1T 2 1T 2-2T 2 2T 2-4T 2 4T .
