The two categories of bend-testing determine the flexibility or strength of a material.
This type of bend-testing determines the smallest radius that a specimen can bend without cracks forming on the outer surface. This bend test is often used to test the flexibility of welds.
Bending strength tests determine the modulus of elasticity and the strength of flat metallic samples in the form of strip, sheet, or plate.
Charpy Impact Testing for Toughness
Charpy Impact Testing is the application of a sudden applied load confined to a localized area of a material to determine its notch toughness or impact strength.
These tests determine a material’s toughness at subzero temperatures. A charpy impact test sample has a V-notch, keyhole, or U-notch machined on one side. It is supported at both ends and struck from behind the notch by a swinging pendulum of fixed mass. The energy that is absorbed by producing the fracture is the material’s impact energy. The more impact energy that a material absorbs, the more robust it is.
This test is often performed to determine the toughness of roll-over protection systems for farm equipment and automobiles. It is also critical in determining the ductile to brittle transition temperature of materials—essential in the failure analysis of structures at subzero temperatures. This material property is crucial for structural members such as bridge girders.
Tension testing is a routinely used method of determining material strength.
The test determines a material’s yield strength, ultimate tensile strength, and percent elongation (ductility). Tension testing assists in establishing if the alloy has been heat-treated to increase strength.
Testlabs International machines tensile test specimens and is capable of performing tension tests at subzero (as low as -40 C), room, or elevated temperatures.
A material’s hardness is a measure of the resistance of a material to surface indentation or abrasion. Hardness is a routinely measured and this parameter can indicate the strength and heat treatment of the material.
A hardness test forces a ball, diamond cone, or pyramid into the material. The total force to the area or depth of indentation provides the measure of hardness.
Hardness testing includes:
Rockwell A, B and C Scale
Rockwell hardness testing is the most widely used method for determining hardness. It can determine the hardness of most metals and alloys, ranging from the softest materials to the hardest steels.
Vickers hardness testing is a form of micro-hardness testing, where a Vickers indenter (square-based pyramidal diamond) is forced into the test surface of the material using loads ranging from 1 to 1000g.
Macro-hardness testing utilizes an applied force much higher than a micro-hardness test. Similar to Micro Vickers hardness testing, a pyramidal diamond indenter is forced into the test surface using loads ranging from 1 to 100 kilograms.
On-site Hardness Testing (Portable Krautramer)
On-site hardness testing is performed on components and structures that cannot be removed from service for laboratory testing. Hardness measurements are calculated based on the rebound of the indenter from the test surface. For this reason, this test method has limitations due to the mass and thickness of the test sample.
Cyclic and Constant Pressure Hydraulic
Pressure testing is used to validate that a pipe, tube, fitting, or component can withstand a designed internal pressure with a margin of safety. Pressure testing consists of non-destructively charging the test sample to a specified, constant pressure, and held for a predetermined duration. At this pressure, the test sample is observed for leaks or other indications of failure.
Pressure testing can also consist of cyclic fatigue testing to determine if the sample can withstand repeated pressure variations without fatigue and failure. This test is valuable as an accelerated evaluation to simulate the life cycle of the test component.