Metallic Materials Testing

Hardness Testing

• The Brinell hardness tester measures the diameter of the impression made by a spherical penetrator on a metal surface, which is then converted to a Brinell number.
• The Rockwell hardness tester measures the depth of penetration of a penetrator into a metal surface, indicated by a Rockwell number on a red or black scale.

Rockwell Hardness Tester

• Uses minor and major loads, with three types of penetrators and three major loads available.
• Provides the same information as the Brinell tester, but measures the depth of penetration instead of the diameter of the impression.

Tensile Strength Testing

• Tests the tensile strength of a ferrous metal by applying a longitudinal load to a sample and plotting the load against the resulting elongations on a graph.
• Provides data on the strength of a metal.

Testing of Metallic Materials

• Testing is carried out with a test piece of the same material and thickness as the component being tested.
• Properties tested for include hardness, tensile strength, fatigue strength, and impact resistance.

Impact Resistance Testing

• The Charpy and Izod impact tests measure the impact resistance (or impact strength) of a metal.
• Both tests involve a pendulum hammer fracturing a notched piece of material with one blow.
• The main difference between the two tests is the beam configuration used.

Charpy V-Notch (CVN) Technique

• A common impact testing method used for metals.
• Involves a specimen with a V-notch, which is struck by a weighted pendulum hammer.
• The pendulum continues its swing, rising to a maximum final height, which is lower than the initial height.

Fatigue Strength Testing

• Establishes the stress level at which structural failure will occur.
• Involves a specially shaped test piece subjected to tension and compression stresses in a rotating machine.
• The number of cycles completed is measured to determine fatigue failure, which is then classified as fatigue life.

Airframe Fatigue Testing

• Aircraft are subjected to fatigue tests to determine the likelihood and causes of premature fatigue damage or wear on the airplane's structure and structural components.
• Provides data for the development of maintenance programs.

Learn about the testing of metallic materials after heat treatment to ensure desired qualities such as hardness, tensile strength, fatigue strength, and impact resistance. Find out how testing is done using a test piece matching the material and thickness of the component.