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.

• Tensile testing.
• Impact testing
• Hardness testing
• Spark 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.

• 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.

• 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

• 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