Proceedings of the
9th International Conference of Asian Society for Precision Engineering and Nanotechnology (ASPEN2022)
15 – 18 November 2022, Singapore
doi:10.3850/978-981-18-6021-8_OR-01-0155
Quenching and Partitioning Treatment of A Low-Carbon Martensitic Stainless Steel Fabricated by Selective Laser Melting
1Department of Mechanical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do 16419, Republic of Korea
2Department of polymer Science and Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do 16419, Republic of Korea
ABSTRACT
Martensitic stainless steels have gained renewed interest recently for their use in automotive, aerospace, and defense applications due to their ultra-high yield strengths and reasonable ductility. However, the toughness of high-strength martensitic stainless-steel shows insufficient under the same strength condition. In this study, Quenching and partitioning (Q&P) treatment was applied to a commercial low-carbon martensitic stainless steel, to improve toughness in martensite stainless steel without compromising the strength. Due to the fine grain and heterogeneous microstructure of the additively manufactured martensitic stainless steel, the quench interruption temperature was optimized with consideration of the carbon concentration in untransformed austenite after partitioning to lower the Ms temperature to room temperature. After partitioning at an appropriate temperature, a significant fraction of austenite was retained through the enrichment of carbon into the untransformed austenite. Moreover, homogeneous microstructure indicated that the effective elimination of the prior selective laser melting formed heterogeneous microstructure of the martensitic stainless steel, and the results of the microstructure analysis show that the austenite retained by the Q&P process is uniformly embedded in the martensitic matrix. The electrochemical results show an effective avoidance of passivation losses and exhibit good corrosion resistance. The significant improvement of ductility and impact toughness in the proposed alloy is mainly a result of the gradual transformation induced plasticity (TRIP) effects, which are caused by carbon-rich retained austenite with heterogeneous stability and carbide-free martensite formed in the Q&P process.
Keywords: Selective laser melting, Martensitic stainless steel, Quenching & partitioning, Heat treatment.
1Department of Mechanical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do 16419, Republic of Korea
2Department of polymer Science and Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon-si, Gyeonggi-do 16419, Republic of Korea
ABSTRACT
Martensitic stainless steels have gained renewed interest recently for their use in automotive, aerospace, and defense applications due to their ultra-high yield strengths and reasonable ductility. However, the toughness of high-strength martensitic stainless-steel shows insufficient under the same strength condition. In this study, Quenching and partitioning (Q&P) treatment was applied to a commercial low-carbon martensitic stainless steel, to improve toughness in martensite stainless steel without compromising the strength. Due to the fine grain and heterogeneous microstructure of the additively manufactured martensitic stainless steel, the quench interruption temperature was optimized with consideration of the carbon concentration in untransformed austenite after partitioning to lower the Ms temperature to room temperature. After partitioning at an appropriate temperature, a significant fraction of austenite was retained through the enrichment of carbon into the untransformed austenite. Moreover, homogeneous microstructure indicated that the effective elimination of the prior selective laser melting formed heterogeneous microstructure of the martensitic stainless steel, and the results of the microstructure analysis show that the austenite retained by the Q&P process is uniformly embedded in the martensitic matrix. The electrochemical results show an effective avoidance of passivation losses and exhibit good corrosion resistance. The significant improvement of ductility and impact toughness in the proposed alloy is mainly a result of the gradual transformation induced plasticity (TRIP) effects, which are caused by carbon-rich retained austenite with heterogeneous stability and carbide-free martensite formed in the Q&P process.
Keywords: Selective laser melting, Martensitic stainless steel, Quenching & partitioning, Heat treatment.
