Destructive Examination


  • Destructive testing, as the name suggests, involves the physical destruction of the completed metal in order to evaluate its characteristics.
  • Destructive testing perform in order to understand a specimen's structural performance or material behaviour under different loads. These tests are generally much easier to get information about any material, and are easier to interpret than nondestructive testing.
  • Destructive testing is most suitable and economic for objects which will be mass produced, as the cost of destroying a small number of specimens is negligible.
  • It is usually not economical to do destructive testing where only one or very few items are to be produced. for example - In the case of a building.

Course Content include common methods used in Destructive Examination
  • Tensile testing.
  • Impact testing
  • Hardness testing
  • Spark testing

1.Tensile Strength Testing
  • “Tensile Testing” is a test in which a prepared sample is pulled until the sample breaks.
  • Test Measurements are recorded in PSI (Pounds per Square Inch) .
  • Test samples called “Tensile Bolts” can reveal a welds Tensile strength, Elastic limit, Yield point, and Ductility.
  • The Elastic Limit of metal means that stress is proportional to strain. it can withstand and still return to the original length after the load is released.
  • Yield Strength occurs when the test sample stretches however will not return to its original length.
  • Ductility is the ability of a metal to stretch or elongate before it breaks.

2. Impact Testing
  • An Impact tester uses a heavy pendulum that is able to measure the amount of force required to shear or fracture a test sample taken from welds “Heat Affected Zone” (HAZ)
  • Impact testing may be performed using either the Izod or Charpy method. (Both methods are similar)
  • A Charpy or Izod test measures the welds ability to withstand an Impact force.
  • Low Charpy test readings indicate brittle weld metal
  • Higher Charpy readings indicate the samples toughness.

3. Hardness testing
  • Hardness may be defined as the resistance to permanent indentation.
  • Four common hardness measuring tests are
  • Rockwell test
  • Scleroscope test
  • Brinell test
  • Microhardness test
  • Microhardness testers allow to measure a materials hardness while leaving the least amount of damage possible on the metals surface.
  • the indenter is used a powerful microscope to determine the amount of indentation into the components surface.
  • The Rockwell testing machine operates somewhat like a press, using a indenter to penetrate the surface of the test sample.
  • The depth of the indentation determines the materials hardness on a scale of 0-100
  • The Scleroscope testing machine measures the amount of “bounce” that a diamond tip hammer rebounds the test sample after being dropped.
  • In the Brinell method presses the “indenter” into a sample for a given period of time.
  • The ability of the sample to resist indentation determines hardness.
  • Technical Specificatio Test loads - 500 to 3000 kg
  • Capacity - Throat 200 mm
  • Max test height - 410 mm

4. Spark Testing
  • The shape and characteristic of sparks created when metal is ground will help to determine its properties.
  • IE: carbon steel , mild steel. Diagram of sparks for spark testing various types of ferrous materials
  • (A) Wrought iron
  • (B) Mild steel
  • © Steel with 0.5 to 0.85% carbon
  • (D) High-carbon tool steel
  • (E) High-speed steel
  • (F) Manganese steel
  • (G) Mushet steel
  • (H) Special magnet steel