What Does Notch Toughness Test Mean?
Notch toughness testing is a method used to quantify a material's ability to withstand an impact with a flaw present in the material. More specifically, a notch toughness test measures the amount of energy a material can absorb. Notch toughness testing is commonly quantified using ft-lbs.
Notch toughness testing is often done at several different temperatures because most materials become more brittle as they become colder. When this happens, toughness decreases. Notch toughness testing helps to determine where this brittle transition temperature occurs.
Corrosionpedia Explains Notch Toughness Test
The Charpy V-notch test is perhaps the most commonly used type of notch toughness test. For a Charpy V-notch test, a sample is machined to a specific rectangular volume. Once the correct dimensions are achieved, a notch is cut into it in the shape of a "V". In order to get reliable results, it is important that these dimensions are as precise as possible. The machined sample is then placed in a fixture with the notch facing away from the impact source. A weight attached to a pendulum arm is then swung at the sample, causing it to fracture. The energy absorbed by the sample is measured by the height the pendulum reaches after impact. The surface of the material is also observed to help determine if the fracture is ductile or brittle.
The Izod impact strength test is another form of notch toughness testing. It is similar to the Charpy V-notch test in that it uses a pendulum and a notch that acts as a stress riser. However, in the Izod impact strength test, the specimen is placed with the notch facing the pendulum. The pendulum strikes the specimen just above the notch. The Izod impact strength is often used for plastics whereas the Charpy V-notch test is not.