Purpose This experiment was intended to make students familiar with some common methods of mechanical testing. The laboratory sessions included mechanical testing such as Rockwell hardness testing the tensile test, the Chirpy impact test, and the Coming end-quench test. Materials and Methods For the first method of this experiment, the Rockwell hardness testing of brass, the TA prepared three different types Of brass for testing. Free machining cartridge brass: 360 brass 70% Cue – 30% Zen) The three types were: the as received brass specimen, the cold rolled brass specimens Of 10%, 20%, 30%, 40%, and 50%, ND the annealed brass specimens from 20% cold-rolled. The last type of brass specimens was annealed at SOCK for times 5, 10, 15, 20, and 25 minutes. The TA then calibrated the scale using a calibration block to ensure accurate measurements.
Five materials were tested: gallivanted steel, brass, aluminum, polymath matriculate (MAMA), and high-density polyethylene (HUDDLE The TA recorded all of the dimensions of each specimen and input them into the Insertion program. The program derives the raw data by using the formulas P/A where engineering stress C is determined by dividing load P by cross-sectional area A and L] = CEIL}L Where engineering strain L] is determined by dividing the change in gauge length LO by the original length of the specimen L. (SQ, SQ, SQ) Each specimen was then loaded into the grips and the mechanized testing began.
Once the specimen reached the failure deformation stage (or as close it gets to it), the Insertion program recorded the data and automated stress -? strain curves for each of the five specimens as shown in figures AAA, b, c, d, and e respectively. The final method transported in the laboratory was the Chirpy Iranian method. Chirpy specimens are bars with square cross-section and v-shaped notch machined into the center of one of the four faces, which creates stress intensity in order to assist in the fracture.
The TA prepared five Chirpy specimens each of 1020 Steel, 2024 Aluminum, and Brass (mom x mom x IMO). Next, the TA placed one specimen of each material into five different environments: Liquid Nitrogen(-ICC), Ice Water(apron CO), room temperature(about ICC), ICC, and ICC. To allow the specimens to reach the temperature of its environment, the samples were left at those temperatures for an adequate amount of time, Immediately after removal from temperature, the TA carefully placed each sample into the Chirpy machine using specialized tongs.
With the machine being zeroed out and the area around it cleared, the impact head (weighted pendulum) was released trot its fixed height. The impact energy as then recorded and tabulated as well as the broken samples to view the ductility. The results from the Chirpy test are shown in Table 2. Table 2 – Raw results from Chirpy test -2100 Celsius Celsius I (Paper ISO C) ART 1000 Celsius 2500 Celsius 1020 steel 1 9. 51 91 90. 51 118. 5 104 | 2024 All 20 121 19 191 16. 51 Brass 17 | 16 | 17. 5 19 | 17. The remaining method that was discussed in this experiment is the Coming quench-test. The Coming quench-end test is the standard method used to measure the heritability of steel. The heritability of steel should not be confused with the hardness of steel. The hardness of steel refers to the measure tot resistance of a material to an applied force, whereas heritability refers to the measure of the capacity of the steel to harden in depth under a given set of conditions. Small phase particles are distributed throughout the steel’s ductile matrix due to precipitation hardening.
By holding an alloy at the solid solution temperature until these particles form, quenching it to keep them from going back into solution and aging at a lower temperature, The aging causes the precipitates to increase in order and produce strain within the matrix crystal, increasing On the other hand, if too much aging occurs hardness Vile decrease, due to the precipitates growing and losing coherence with the matrix. (IQ) Therefore the driving force behind the hardening is the temperature time. SQ) Discussion Hardness is a property of material, Vichy quantifies its resistance to plastic deformation. Hardness testing is important because you can determine when the steel Starts to separate and becomes weak, which would highly important if you were using the steel to build a bridge. Engineers would be able to see that the bridge is no longer sturdy or safe and that it is time for a new one. Another example when hardness is important is when design a bike. It is important because designers must insure that the metal won’t bend or brake when a person of larger weight gets on the bike.