Effect of Nitrogen Partitioning on Yield Strength in Nitrogen-Alloyed Duplex Stainless Steel During Annealing
- PDF / 2,149,965 Bytes
- 6 Pages / 593.972 x 792 pts Page_size
- 43 Downloads / 243 Views
tenitic stainless steel (ASS) has excellent corrosion resistance and high toughness, but it has low yield strength. Ferritic stainless steel (FSS) has high yield strength, though it shows low ductility.[1] Duplex stainless steels (DSS) are defined as a family of steels consisting of two phase microstructures of ferrite and austenite. Through the optimum mixture of the desirable properties of ASS and FSS, DSS has an attractive combination of good mechanical properties and excellent resistance to stress corrosion cracking.[1,2] Extensive studies have done to elucidate the relationship between the phase fraction and the mechanical properties of DSS[1,3–5]: Park and Lee[1] and Floreen and Hyden[3] showed that an increase in the ferrite fraction in DSS resulted in a decrease of the tensile strength and elongation but a linear increase in the yield strength. In addition, Park and Lee[1] presented empirical models to predict the tensile strength, yield strength, and elonga-
MIN-HO JANG, Ph.D. Student, is with the Division of Materials Science and Engineering, Hanyang University, Seongdong-ku, Seoul 133-791, Republic of Korea, and also with the Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon, Gyeongnam 642-831, Republic of Korea. JOONOH MOON, Senior Researcher, and TAE-HO LEE and SEONG-JUN PARK, Principal Researchers, are with the Ferrous Alloy Department, Advanced Metallic Materials Division, Korea Institute of Materials Science. Contact e-mail: [email protected] HEUNG NAM HAN, Professor, is with the Department of Materials Science and Engineering, Seoul National University, Seoul 151-742, Republic of Korea. Manuscript submitted August 5, 2013. METALLURGICAL AND MATERIALS TRANSACTIONS A
tion as a function of the ferrite fraction. Badji et al.[4] investigated the effect of the annealing temperature on the microstructure and mechanical properties in the weld heat-affected zone (HAZ) of DSS, showing that the yield strength of the weld HAZ increased with an increase in the ferrite fraction.[4] Unnikrishnan and Mallik[5] reported that the mechanical properties of DSS depend on the formation of the r phase at a low annealing temperature [1273 K (1000 °C)]; i.e., the yield strength increases with the formation of the r phase and an increase of the ferrite fraction. Many previous studies were interested mainly in the effect of the ferrite fraction on the strengthening of the DSS during a heat treatment, as ferrite is harder, therefore, significantly affecting the strength as compared to austenite. However, a few studies have recently focused on the role of austenite.[6,7] Foct and Akdut[6] investigated the microhardness of ferrite and austenite in DSS containing different nitrogen (N) contents and found that ferrite is harder than austenite if the nominal N content is less than 0.12 wt pct, whereas austenite is harder than ferrite if the nominal N content is higher than 0.12 wt pct, as the N content partitioned into austenite increased with an i
Data Loading...
