Tensile Testing

Equipment Used for Testing:
Universal Testing Machine

• Ultimate Tensile Stress (U.T.S.):
  It is the highest value of the stress that the material can bear or sustain without fracture.
• Breaking Stress or Fracture Stress:
  It is the stress value at the point of fracture or failure.
• Yield Stress:
  It is the stress at which the material yields i.e. shows appreciable plastic deformation at almost constant stress without any strain hardening. This stress exists in some materials like low carbon steels and mild steel.
• Proof Stress:
  Proof Stress is reported for those materials which do not show yield point or well defined straight line portion on their stress strain diagrams and is an equivalent term to the yield stress or elastic limit stress. Proof stress is defined as the stress at which the material shows a specific amount of plastic deformation or permanent set. This specified amount of plastic deformation is of the same order as that observed during yielding of the materials which show yield point and is between 0.1 and 1.0 percent. If nothing is specified. It is customary to evaluate the proof stress at 0.2% permanent deformation.
• Ductility:
  It is the ability of the material to exhibit large plastic deformation prior to fracture under tensile loading conditions. It is also defined as the ability of a material to be drawn into five wires. Ductility is expressed by percent elongation.
• Malleability:
  It is the ability of a material to exhibit large plastic deformation prior to fracture under compressive loading conditions. It is also defined at the ability of a material to be rolled into thin sheets. Since the test is tensile, malleability of a material cannot be accurately determined from this test. However, an approximate idea about malleability can be obtained from % reduction in cross-sectional area of the specimen.