Impact Testing of V-Notched Metal Xias
The V-notched metal Xias is a commonly used testing method used to determine the impact resistance of engineering materials. It is also called the Charpy test in the United States and the Izod test in Britain. It is based on successful experiments that measure the impact toughness of metal materials. The test method is widely used in many engineering industries for research, assessment and quality control.
The testing method begins by cutting out a notch of a specified size in a rectangular specimen of the material to be tested. The size of the notch is determined by the required impact energy, with the deeper the notch, the lower the impact energy required. The specimen is then placed in a specified testing mechanism, which is set to clamp up the two ends of the sample before the impact test proper.
When the specimen is clamped up, a hammering or swinging arm is released so that it strikes a blunt instrument that impacts on one end of the sample. The reaction at the other end of the specimen is measured by a force gauge or any other instrument specified. Information such as impact energy and deformation are used to obtain a ‘notch toughness’ value.
The test method has some limitations in that it gives only an idea of the performance of the material subjected to impact energy. Different testing procedures have been designed to make up for the drawbacks in the testing method. Nonetheless, the V-notched metal Xias is still widely regarded as the standard for testing materials for their impact resistance.
The Edgeworth-Kuhn modified V-notched Xias test further improves the accuracy of the results. In this test, the notches have 90° angles instead of the 45° angles of the standard test, allowing more accurate measurements for the per cent shear as the sample deforms and breaks.
Another variation of the standard V-notched Xias test is the full-cut V-notched test. This test is used when the material is too tough to be tested with standard notches. In this case, a larger sample of the material is cut so that the notch is ‘fully charged’ with an area of greater than 2x2mm2.
The full-cut V-notched test results in a higher impact energy than the standard test, making it suitable for tougher materials such as alloy steels. The results obtained with the full-cut method are more reliable than those of the standard method as the notch is fully charged, making the impact energy measurement more accurate.
In conclusion, the V-notched metal Xias test is a widely accepted testing method for determining the impact resistance of materials. There are various variations of the test that offer different levels of accuracy which allow the test to be used for a range of materials, from the toughest alloys to the more brittle materials. The results from the V-notched Xias test gives engineers an insight into the mechanical properties of a given material and helps them to take informed decisions in the design, selection and implementation of engineering materials.
