Hydrotest temperature must avoid which region to prevent brittle fracture?

Hydrotest temperature must avoid which region to prevent brittle fracture?

• A. Elastic region
• B. Plastic region
• C. Creep region
• D. Brittle fracture region

Answer: (D)

The key idea is that metals can become brittle at low temperatures, where toughness is low and cracks can propagate suddenly under stress. During a hydrotest, applying internal pressure can drive the material to fracture if it lies in its brittle regime. To prevent this, the test temperature should be kept out of the brittle fracture region and kept in the ductile range where the material can deform plastically and arrest crack growth. The elastic region describes reversible, non-permanent deformation and isn’t where brittle fracture behavior is governed; the plastic region involves permanent deformation but does not by itself define brittleness; creep occurs at high temperatures with time-dependent deformation and isn’t the concern for typical hydrotests. In short, avoid the brittle fracture region to prevent sudden fracture.

The key idea is that metals can become brittle at low temperatures, where toughness is low and cracks can propagate suddenly under stress. During a hydrotest, applying internal pressure can drive the material to fracture if it lies in its brittle regime. To prevent this, the test temperature should be kept out of the brittle fracture region and kept in the ductile range where the material can deform plastically and arrest crack growth.

The elastic region describes reversible, non-permanent deformation and isn’t where brittle fracture behavior is governed; the plastic region involves permanent deformation but does not by itself define brittleness; creep occurs at high temperatures with time-dependent deformation and isn’t the concern for typical hydrotests. In short, avoid the brittle fracture region to prevent sudden fracture.