Cyclic endurance of ferritic-pearlitic grade steels in thermal cycling at reduced temperatures

Tests were conducted on wide flat specimens of 09G2S and 20 steels to determine the relationship governing the behavior of ferritic-pearlitic steels under the conditions of cyclic temperature change in the range from 20°C to -40°C. At a temperature of -40°C, cooling was interrupted and the specimen was heated naturally to ambient temperature. The specimens had stress raisers in the form of a notch to simulate various defects. For comparison, specimens were also tested at fixed temperatures in the same range. It was concluded that thermal cycling tests of materials to be used for oil and gas installations should be conducted in the climatic spectrum that the material will experience in the field and not at fixed temperatures.