Impact experiment report 冲击实验报告.docx

Division of EngineeringStructural MaterialsIMPACT TEST1. IntroductionThe aim of this experiment is to explore three steels ability of impact resistance. This three steel was different treated before test, one is without any treatment as an original compare, one is 860 normalization and 300, the final one is 860 normalization just as the one before, but with 700 tempering. Impact test is used to test impact strength. Its standard method is Izod test. In mechanics, Impact strength is a high force or shock applied over a short time period when two or more bodies collide. It usually has a greater effect than a lower force applied over a proportionally longer time period of time. The effect tempering , depends critically on the relative velocity of the bodies to one another. A notched sample is generally used to determine impact strength.The Izod test consists of measuring the energy absorbed in breaking a specimen clamped vertically against the Anvil. The striker is mounted within the hammer with its edge in a horizontal plane on impact. The specimen is usually either of 10mm square section with either one or more “V” notches. The blow is struck at a fixed height above the notch which is positioned level with the top of the clamp plate. At last, people can read off the resultant energy absorbed by breaking the specimen from the position of the reading pointer against the Izod scale on the dial.2. Experimental Setup3. Procedure1. For conducting Izod tests the Izod Support arm, cross beam and ancilliary weights on each side of the hammer must be fitted. The Izod striker must be fitted within the pendulum hammer and clamped by the wedge clamping piece, ensuring that the fastening screws are fully tightened. Changing the striker should only be carried out whilst the hammer is safely supported by the wooden support block.2. The appropriate set of specimen holding grips for the Izod tests must be fitted to the Anvil. Changing grips involves removal of the anvil from the base by releasing the four set screws to reveal the screws holding the fixed section of the grips which can then be changed. With the central clamp screw released, the loose section of the grips may then be inserted behind the clamp plate. The anvil should be replaced and securely fastened on the base by the socket head screws.3. Place the specimen in the grips and tighten with the clamping screw. The specimen should be placed in such a way that the notch is facing the direction of impact of the pendulum and directly in line with the top of the clamp plate.4. With the pendulum hanging down freely and the striker just touching the specimen, set the pointer to 160J on the Izod dial scale and in contact with its carrier. 5. Raise the pendulum to the Izod (lower) release position and ensure it is securely latched. The pointer carrier should have rotated with the pendulum. 6. Move the pointer to be in contact with the carrier, taking care not to disturb it.7. After ascertaining that it is safe to do so, release the pendulum by operating lever.8. Wait until the pendulum has broken the specimen and completed its initial swing before carefully applying the pendulum brake to slow down the pendulum and bring it to a gentle stop.9. Read off the resultant energy absorbed by breaking the specimen from the position of the reading pointer against the Izod scale on the dial.10. Remove the broken specimen from the machine and reset the pointer and carrier on 160 J as in 5 above and repeat the procedure.4. ResultsAll specimens were 70mm long with one 2mm deep notch and had a 10mm square section. These three experiments all supposed started at 160J.MaterialEnergy to make it break(J)Energy to make it break(DIV)No treatment7437860 normalize300 temper9748.5860 normalize 700 temper11959.51 DIV = 2 JThe energy absorbed by the specimen can be calculated byEabsorbed=Etotal(1-0.5%)Absorbed energy:No treatment :74 * 99.5% = 73.63 J860 normalize300 temper : 97 * 99.5% = 96.515 J860 normalize 700 temper : 119 * 99.5% = 118.405 J5. DiscussionIn this experiment, three types of specimens are all hit by the striker on the edge of the hammer and broken with a ruptured sound in a sudden. The specimen nearly broke into two parts with one ruptured area which has a gap on hitting side. In the same time, the dial pointer rotated and stopped in a max change angle which means the left energy. So the larger changed angle of dial pointer means less energy being absorbed. Form the reading pointer we got the data of no treatment steel is 97J, tempering 300 is 97J, and tempering 700 is 119J. It is clear that normalization and tempering make steel harder than the one without treatment and it can also be found that higher tempering temperature do effect in same way. Moreover, as the loss of friction is 0.5%, the energy absorbed by the specimen could be calculated easily. The energy absorbed by three specimens in sequence are 73.63J, 96.515J and 118.405J.6. ConclusionThis experiment shows that different treatment in temperature will cause different intensity of steel. It is obviously that the first steel with no treatment has the lowest intensity and absorbed 73.63J energy, steel with 700 tempering has middle intensity which absorbed 96.515J energy, the hardest one is 700 tempering, absorbed the most 118.405J. In application, this phenomenon can be used to manufacture steel in different level of intensity. In this case, it becomes easier to satisfied co