The fracture of different materials under impact
can you do a paraphrase for the paper that is attached
Abstract
Engineers in group number 3 did experiment 2 after studying the fracture energy of materials under an impact, the specimens (1018-steel) & (2024-aluminum) and charpy impact tester. The experiment contained 5 specimens of steel and 5 specimens of aluminum, thermocouple, temperature bath, charpy impact machine, tongs and digital caliper. Moreover, widths, impact energy, change of width and shear lip % are the data measured from the experiment. The specimens of each material was immersed in 5 different temperatures starting from -79 C to 100 C for 10 minutes before placing each specimen to the charpy impact tester. The overall outcome for steel is that as the temperature increases the impact energy, change in width and shear lip % increases. As for the aluminum, the result shows that the impact energy, change in width and shear lip % doesn’t depend on temperature.
Introduction
Many properties of materials depend on temperature such as hardness, width and shear lip etc. Sometimes materials show some brittleness, which impedes their use in a given design. In order to discover brittleness in certain materials, an impact energy test must be applied to the material. Some materials need more force in order to fracture, as shown in the experiment and the different impact energy needed to fracture steel and aluminum. However, most of body-centered-cubic materials show transition from ductile to brittle behavior due to temperature. Therefore, as the temperature increases the fracture energy increases. Moreover, according to lab manual “the steel specimens for this experiment are manufactured from a single ingot of steel and are machined to a single drawing.” The shear in the surface failure of steel can be found by looking the fresh failure surface under a low power magnification.
Procedure
– After the safety considerations had been reviewed, each specimen was labeled using a hammer and punch.
– Initial lateral dimensions was measured and recorded for all specimens.
– An impact energy test for five 1018-steel and five 2024-alumunim specimen were applied after immersed each specimen of steel and aluminum in five different baths which are dry ice, antifreeze, ice, room temperature and boiling water for ten minutes. Then a special tong was used to take the charpy immediate to the machine in the correct position.
– Lateral diminutions were measured after the impact. Also, the natures of the fractured surface of steel specimens were observed carefully and with attention paid.
Discussion and Result
Table 1: measurements of impact energy for steel and aluminum.
| 1018 – Steel | 2024 – Aluminum | ||
| Temperature © | Impact Energy (ft-lb) | Impact Energy (ft-lb) | |
| S6 | -79 | 4.4 | 17 |
| S7 | -40 | 12 | 12 |
| S8 | 0 | 45 | 16 |
| S9 | 23 | 51 | 12 |
| S0 | 100 | 97 | 12 |
Figure 1: Impact energy for steel and aluminum against temperature.
Table 2: measurements of the change of width for both steel and aluminum.
| 1018 – Steel | 2024 – Aluminum | ||
| Temperature © | Change in Width (in) | Change in Width (in) | |
| S6 | -79 | 0.38 | 0.393 |
| S7 | -40 | 0.367 | 0.388 |
| S8 | 0 | 0.406 | 0.397 |
| S9 | 23 | 0.411 | 0.392 |
| S0 | 100 | 0.449 | 0.395 |
Figure 2: The change of width for both steel and aluminum versus temperature.
Table 3: data recorded of the shear lip percent for steel and aluminum.
| 1018 – Steel | 2024 – Aluminum | ||
| Temperature © | Shear Lip % | Shear Lip % | |
| S6 | -79 | 10 | 10 |
| S7 | -40 | 10 | 10 |
| S8 | 0 | 20 | 10 |
| S9 | 23 | 50 | 10 |
| S0 | 100 | 50 | 10 |
Figure 3: shear lip percent for steel and aluminum in different temperature values.
Table 4: temperature and impact energy values for steel.
| Steel | Temp °C | ||||
| Impact
energy (ft-lbs) |
-70 | -44 | 0 | 25 | 100 |
| 5 | 35 | 57 | 78 | 65 | |
| 7 | 32 | 48 | 69 | 83 | |
| 18 | 26 | 55 | 67 | 94 | |
| 14 | 39 | 54 | 68 | 80 | |
| 10 | 27 | 67 | 75 | 95 | |
| 10 | 30 | 63 | 76 | 90 | |
| 5 | 16 | 35 | 76 | 94 | |
| 6 | 16 | 34 | 76 | 103 | |
| 5 | 16 | 61 | 76 | 94 | |
| 6 | 17 | 47 | 66 | 73 | |
| 13 | 19 | 54 | 70 | 85 | |
| 8 | 19 | 41 | 66 | 108 | |
Table 5: temperature and impact energy values for aluminum.
| Aluminum | Temp °C | ||||
| Impact energy
(ft-lbs) |
-70 | -44 | 0 | 25 | 100 |
| 9 | 10 | 9 | 8 | 8 | |
| 8 | 9 | 8 | 9 | 8 | |
| 9 | 8 | 9 | 8 | 9 | |
| 9 | 8 | 8 | 8 | 9 | |
| 10 | 10 | 10 | 10 | 10 | |
| 9 | 10 | 11 | 10 | 8 | |
| 8 | 7 | 9 | 11 | 11 | |
| 8 | 8 | 7 | 8 | 8 | |
| 11 | 7 | 8 | 7 | 9 | |
| 8 | 7 | 7 | 8 | 7 | |
| 6 | 7 | 7 | 8 | 8 | |
| 7 | 8 | 8 | 8 | 8 | |
The Standard Deviation is give by:
Where: xi = individual fracture energy value
n= number of values (data points)
Table 6: data and measurements of the average fracture energy, upper and lower standard deviation for aluminum.
| 2024 – Aluminum | ||||
| Temperature © | Average Fracture Energy (ft-lb) | Upper Standard deviation | Lower Standard deviation | |
| A1 | -79 | 9.2 | 11.87226975 | 6.527730245 |
| A2 | -40 | 8.5 | 10.06073618 | 6.939263816 |
| A3 | 0 | 9 | 11.41522946 | 6.584770542 |
| A4 | 23 | 8.8 | 10.2632244 | 7.336775601 |
| A5 | 100 | 8.8 | 10.20511885 | 7.394881153 |
Figure 4: The avarge fructure energy, upper and lower standerd deviation for aluminum due o temperutre.
Table 7: data and measurements of the average fracture energy, upper and lower standard deviation for steel.
| 1018 – Steel | ||||
| Temperature © | Average Fracture Energy (ft-lb) | Upper Standard deviation | Lower Standard deviation | |
| S6 | -79 | 8.6 | 12.82046297 | 4.379537029 |
| S7 | -40 | 23.4 | 32.00753993 | 14.79246007 |
| S8 | 0 | 50.8 | 61.11056217 | 40.48943783 |
| S9 | 23 | 70.3 | 77.59594197 | 63.00405803 |
| S0 | 100 | 89.3 | 101.1910654 | 77.40893462 |
Figure 5: The avarge fructure energy, upper and lower standerd deviation for steel due o temperutre.
The type of fracutre observed for the aluminum due to tempruture was different from the one observed in the steel. For example, the shear of the aluminum was stabeld and didn’t change with changing temperutre. Morover, steel sheer increased by increasing the tempreture as seen in Figure 3.
As seen in Figure 1, aluminum imapact energy was nither increasing nor decreasing while the temprutere was increasing. However, steel had a different results, as the tempreture increased, the impact energy also decreased.
Conclution
Each metrial has it’s own proprties. As the expermint was done, we indicated that some matirials proprties depend on tepmretures and other doesn’t. As for this expermint, the impact energy tansition from ductile to brittle was determined also with the average fracutre energy, upper and lower standerd deviation.
Refrencess
Revised Laboratory Manual Expereminet 2: Notched Bar Impact Testing Of matirals http://www.csun.edu/~bavarian/mse_227_lab.htm
David G. Rethwisch, William D. Callister Jr, Fundamentals of Materials Science and Engineering: An Integrated Approach, John Wiley & Sons, NY, 4th Edition, 2012
Coach Anthony Magee, MS, MBA, Forensic Metallurgist, Project Leader and Business Strategist.
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Experiment Report
Abstract
Having learnt the theory behind the fracture of different materials under impact, the group number 3 conducted an experiment to understand the same. On the charpy impact tester, the specimens, 1018 steel and 2024 aluminium samples were tested. To conduct the experiment, the materials for the exercise at the disposal of the group of engineers included: 5 specimens of steel, 5 specimens of aluminium, thermocouple, temperature bath, tongs…………….
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