http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
직접 에너지 적층 공정을 이용한 보수 공정에서 보수 폭에 따른 기계적 특성 관찰
오욱진(Wook-Jin Oh),신광용(Gwang-Yong Shin),손용(Yong Son),심도식(Do-Sik Shim) 한국기계가공학회 2020 한국기계가공학회지 Vol.19 No.3
This study explores the effects of repair width on the deposition characteristics and mechanical properties of stainless steel samples repaired using direct energy deposition (DED). In the DED repair process, defects such as pores and cracks can occur at the interface between the substrate and deposited material. In this study, we changed the width of the pre-machined zone for repair in order to prevent cracks from occurring at the inclined surface. As a result of the experiment, cracks of 10–40 μm in length were formed along the inclined slope regardless of the repair width. Yield and tensile strength decreased slightly as the repair width increased, but the total and uniform elongation increased. This is due to the orientation of the crack. For specimens with a repair width of 20 mm, yield and tensile strength were 883 MPa and 1135 MPa, respectively. Total and uniform elongations were 14.3% and 8.2%, respectively. During observation of the fracture specimens, we noted that the fracture of the specimen with an 8 mm repair width occurred along the slope, whereas specimens with 14 mm and 20 mm repair depths fractured at the middle of the repaired region. In conclusion, we found that tensile properties were dependent upon the repair width and the inclination of the crack occurred at the interface.
초음파나노표면개질로 표면처리된 316 스테인레스강의 고온 경도 및 고온 마모에 관한 연구
조승영(Seung-Young Cho),신광용(Gwang-Yong Shin),이기용(Ki-Yong Lee),심도식(Do-Sik Shim) 한국기계가공학회 2023 한국기계가공학회지 Vol.22 No.2
This study investigated the effect of ultrasonic nanocrystal surface modification (UNSM) on the hardness and wear behavior of AISI STS316L at elevated temperatures. 316L stainless steel was treated by UNSM installed in CNC lath, and its hardness and wear behavior at elevated temperature were tested. Compared with the untreated sample (206 Hv), the hardness of the UNSM-treated sample was improved by 59% (328 Hv). Thus, at high temperature, even though the hardness both samples decreased, it was better for UNSM-treated samples. Further, the wear resistance of the UNSM-treated sample was superior to that of the untreated sample at room temperature, but the wear loss in UNSM-treated sample increased at 250°C and 500°C. Meanwhile, the grain size of the UNSM-treated sample increased as the temperature increased. This is because the recrystallization temperature of UNSM-treated sample decreased, resulting in grain recovery due to the increase in temperature near the surface after repeated friction in a high temperature environment.