ISO 148-2:1998 pdf download – Metallic materials – Charpy pendulum impact test
1 Scope
This part of ISO 1 48 covers the verification of the constructional elements of pendulum-type impact testing machines. It is applicable to machines with 2 mm or with 8 mm strikers used for pendulum impact tests carried out, for instance, in accordance with ISO 1 48-1 . It can analogously be applied to pendulum impact testing machines of other capacities and of different design. Impact machines used for industrial, general or research laboratory testing of metallic materials in accordance with this part of ISO 1 48 are referred to as industrial machines. Those with more stringent requirements are referred to as reference machines. Specifications for the verification of reference machines are found in ISO 1 48-3. This part of ISO 1 48 describes two methods of verification. a) The direct method which is static in nature and involves measurement of the critical parts of the machine to ensure that it meets the requirements of this part of ISO 1 48. The verification equipment shall have a certified traceability to the International Unit System. The direct method shall be used when a machine is being installed or repaired, or if the indirect method gives an incorrect result. b) The indirect method, which is dynamic in nature, and which use reference test pieces to verify points on the measuring scale. A pendulum impact testing machine is not in compliance with this part of ISO 1 48 until it has been verified by both the direct and indirect methods (see clause 1 2). The requirements for the reference test pieces are found in ISO 1 48-3. NOTE — This part of ISO 1 48 takes into account the total energy absorbed in fracturing the test piece using an indirect method. This total absorbed energy consists of 1 ) the energy needed to break the test piece itself and 2) the internal energy losses of the pendulum impact testing machine performing the first half-cycle swing from the initial position.
3.1.1 anvil: The portion of the base of the machine forming a vertical plane which restrains the test piece when it is struck by the pendulum (see figures 1 to 3), the plane of the supports being perpendicular to the plane of the anvil.
3.1.2 base: That part of the framework of the machine located below the horizontal plane of the supports.
3.1.3 centre of percussion: That point in a body at which, on striking a blow, the percussive action is the same as if the whole mass of the body was concentrated at the point (see figure 4). NOTE — When a simple pendulum delivers a blow along a horizontal line passing through the center of percussion, there is no resulting horizontal reaction at the axis of rotation.
3.1.4 centre of strike: That point on the striking edge of the pendulum at which, in the free hanging position of the pendulum, the vertical edge of the striker meets the upper horizontal plane of a test piece of half standard height (i.e. 5 mm) or equivalent gauge bar resting on the test piece supports (see figure 2).
3.1.5 industrial machine: Impact machine used for industrial, general, or most research-laboratory testing of metallic materials. These machines are not used to establish reference values. Industrial machines are verified using the procedures described in this part of ISO 1 48.
3.1.6 reference machine: Pendulum impact testing machines used to determine the reference energy of a reference test piece. The verification requirements for this grade of machine are more stringent than those for industrial machines and are contained in ISO 1 48-3.
3.1.7 striker: The portion of the hammer that contacts the test piece. The edge that actually contacts the test piece may have a radius of 2 mm (the 2 mm striker) or a radius of 8 mm (the 8 mm striker).