PSI - Issue 59

Teguh Muttaqie et al. / Procedia Structural Integrity 59 (2024) 222–229 Muttaqie et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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In order to guarantee that the specimens are representative of the material being tested, the dimensions should be specified based on the accepted testing methods and should be strictly controlled. To achieve this manner water jet cutter was used to cut the specimen from the SUS 304 base plate, whereas the wire cutter used to fabricate the notched. 4. Test methodology The concept of energy in the Charpy impact test is that the energy received by the test material during the pendulum strike will be translated into energy of damage or energy of loss. The greater the energy received by the test material, the smaller the strength of the test material to withstand the sudden load (impact load). The notch impact energy (KV) is equal to the difference in potential energy of the pendulum at the starting position and first reversal after the swing, as presented in Equation 1. (1) where m is the mass of the hammer and g is the gravitational acceleration. At the starting point, the striker is released from a fixed height H . The knife edge mounted on the pendulum then strikes the specimen placed behind the notch, which acts as a stress concentration that triggers fracture during this high-velocity impact. After the impact takes place, the pendulum goes through its first reversal with a maximum height h , which is lower than H . ), The first step in conducting a Charpy V-notch impact test on a Type 304 stainless steel specimen is to accurately measure the specimen to ensure it meets the standards for the test. This involves using precision measuring equipment to verify the dimensions of the specimen, including its thickness, width, and length. The V-notch should also be carefully measured to ensure it meets the specified depth and angle requirements for the test. 4.2. Conditioning of specimen temperature After the specimen has been measured, it must be conditioned to the test temperature. This involves exposing the specimen to a controlled temperature environment for a specified amount of time to allow it to reach a stable temperature. For Type 304 stainless steel, the test temperature is set in the range of - 196°C to low temperature. During temperature conditioning, the specimen is immersed in liquid nitrogen and allowed to stabilize at the cryogenic temperature for approximately 10 minutes. The time from taking out the specimen to completing the impact is less than 10 s. The temperature of the specimen is monitored using a thermocouple sensor connected to the data logger. The specimen is then placed in the center position on the anvil. When the temperature rises to the desired level, the striker is released 4.3. Testing and metallographic observation Once the knife edge of the striker hits the specimen at the test temperature, the dial indicator displays the energy absorbed by the specimen. The test results are recorded and observations of the fracture surface are then performed. Finally, a metallographic observation of the specimen may be conducted to examine the microstructure and evaluate any changes that may have occurred during the test. This can provide valuable information on the behavior of the material under the conditions of the test, and can be used to improve the design and performance of LNG storage tanks made from Type 304 stainless steel. 4.1. Measurement of specimen