12Cr 강의 화염경화 표면처리 층의 초음속 물방울 충격에 의한 손상 거동 = Deformation behavior of Flame-hardened Surface Layer of 12Cr Steel by Supersonic Water Drop Impacts

다국어 초록 (Multilingual Abstract)

Water drop impact erosion properties of the 12Cr steel, currently used as nuclear steam turbine blade material, surface-hardened by the flame hardening process have been characterized. For this, variations of both the maximum erosion depth de,,,,ax and volume loss V with the cumulative impacts n at the supersonic impact velocity (~350 m/s) have been investigated for the as-received and flame-hardened 12Cr steels with different hardnesses. Typically all the samples showed an erosion-time characteristic involving the incubation period initially followed by the steady state period. It is also found that the d_(e,max) increases stepwise-like with the number of impacts n, which results from a sudden formation of craters by crack propagation. Compared to those for the as-received 12Cr steel, the flame-hardened ones showed an excellent resistance to water drop impact erosion with 2.2~2.8 times higher incubation time n, and 115~1/8 times lower erosion rate a. In the incubation period the as-received 12Cr steel was damaged by ductile depression and ploughing, while the flame-hardened 12Cr steel by fatigue cracks and brittle platelet deformation. Erosion in the steady state period was developed by the cleavage fracture commonly.
(Received July 22, 2004)

목차 (Table of Contents)

• Abstract
• 1. 서론
• 2. 실험방법
• 3. 실험결과 및 고찰
• 4. 결론
• 후기
• REFERENCES