서브제로 처리한 202 스테인리스강의 기계적 및 탄성파 특성

Abstract

This study investigated the mechanical properties and the dominant frequency of the elastic waves from the tensile test. The specimen was rolled with five different rolling degrees (10, 22, 33, 42 and 50%), which was treated as a subzero. The specimen was rolled at room temperature, which was transformed from austenite to martensite (only α-martensite). The higher rolling degree, the lower the subzero treatment temperature whereas the longer treatment time led to more martensite formation at the same rolling degree. Mechanical properties (tensile strength, yield strength, and Vickers hardness) increased at higher rolling degree and lower subzero temperature. Better mechanical properties were also observed with a longer treatment time at the same subzero temperature. However, the elongation was inversely proportional to the mechanical properties. The dominant frequency increased with an increase in the rolling degree regardless of the subzero temperature, and decreased after 33% of the rolling degree. On the other hand, higher frequency band was obtained at lower temperature and long time. The dominant frequency increased when the amount of α-martensite increased and decreased with the α-martensite amount between 50-65%. The lower subzero treatment temperature increased the amount of α-martensite, which resulted in the higher dominant frequency. The longer treatment time at the same subzero temperature led to an increase in the amount of α-martensite, leading to high dominant frequency.