Charpy V-Notch Test Sample
Welding Procedure and Welding Qualification
- Metallographic Cross-Section
- Tensile Test
- Bend Test
- Charpy Test
A cross-section sample is obtained from the test specimen through destructive methods.The surface of the cross-section sample is then polished with an increasingly finer grain until the desired surface profile is achieved. The sample is then submerged in an acidic solution and, if required, an electric current will be applied in order to expose the weld structure. After that, a Certified Weld Inspector will inspect the part for any discontinuites under a microscope with a maginifcation power of up to 1000x
A specimen is prepared by reducing the area around the weld to a size that varies according to the specification required. Both ends of the specimen are given sufficient area so that it is firmly gripped during testing. Our test machine has two crossheads; one is adjusted for the length of the specimen and the other is driven to apply tension to the test specimen. The test process involves placing the test specimen in the testing machine and slowly extending it until it fractures. The data produced is then analyzed according to specification in order to determine the outcome of the test.
Bend tests for ductility provide a simple way to evaluate the quality of materials by their ability to resist cracking or other surface irregularities during one continuous bend. After bending, the convex surface of the bend is examined for evidence of a crack or surface irregularities. If the specimen fractures, the material has failed the test. When complete fracture does not occur, the criterion for failure is the number and size of cracks or surface irregularities visible to the unaided eye occurring on the convex surface of the specimen after bending, as specified by the product standard.
The Charpy V-notch test is a standardized high strain-rate test which determines the amount of energy absorbed by a material during fracture. This absorbed energy is a measure of a given material's notch toughness.The apparatus consists of a pendulum of known mass and length that is dropped from a known height to impact a notched specimen of material. The energy transferred to the material can be inferred by comparing the difference in the height of the hammer before and after the fracture.
The size of the sample can also affect results, since the dimensions determine whether or not the material is in plane strain. This difference can greatly affect conclusions made. OCTI has experienced technicians and required cutting machines that enables us to cut the sample down to the required dimensions so that our results are as accurate as possible.