Super-duplex stainless steels are in great demand in various industrial fields such as chemical processing and seawater desalination due to their excellent pitting corrosion resistance. However, detrimental phases can easily form during fabrication, and even minor additions of alloying elements can significantly impact their microstructure and properties. This study investigated the effects Cu or Ti additions on a super-duplex stainless steel. First, the effects of annealing time at 950 °C on the microstructure and corrosion characteristics were investigated. It was found that as the annealing time increased, the fraction of sigma phase increased; however, the corrosion resistance in the electrochemical test using a 3.5 % NaCl electrolyte showed only a slight improvement. The microstructure of duplex stainless steel with added Cu or Ti did not differ significantly from that of the base steel. However, the overall corrosion resistance showed improvement, and in particular, an observed increase in pitting potential. Investigating the characteristics of the passive film on the alloy surface revealed that the stability of the passive film was higher in alloys with added Cu or Ti compared to the standard alloy. Among these, the alloy with Cu addition had the thickest film, while the Ti-added alloy had the highest Cr concentration and a film thickness greater than that of the standard alloy.

Abstract
1. 서 론
2. 실험 방법
3. 결과 및 고찰
    3.1. 듀플렉스 내식강의 부식특성에 미치는 가열시간의 영향
    3.2. 듀플렉스 내식강의 부식특성에 미치는 구리 및티타늄 첨가의 영향
    3.3. 부동태 산화막의 특성에 미치는 구리 및 티타늄첨가의 영향
4. 결 론
Acknowledgement
References

• 한윤기(국립한밭대학교 신소재공학과) | Yun-Gi Han (Department of Materials Science and Engineering, Hanbat National University, Daejeon 34158, Republic of Korea)
• 김정민(국립한밭대학교 신소재공학과) | Jeong-Min Kim (Department of Materials Science and Engineering, Hanbat National University, Daejeon 34158, Republic of Korea) Corresponding author