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    Investigation of the casting microstructure of a Fe-base, Cr-Ni-Mo duplex alloy
    (Elsevier Science Sa Lausanne, 1997) Ceylan, M; Kuzucu, V; Aksoy, M; Aksoy, I; Kaplan, M; Yildirim, MM
    The microstructures of Fe-base cast duplex stainless steel specimens, which contain Cr, Ni, Mo and other elements and have been subjected to various heat treatments, were examined with X-ray diffraction, thermal analysis and optical microscopy and their hardnesses were also measured. From the metallographic examinations, it was seen that these specimens included austenite, ferrite, some inter-metallic phases, grain boundary carbides and oxide inclusions. It has been determined that the amount of grain-boundary carbides decreased, and second-phases precipitated in ferrite, in specimens annealed at 950 degrees C for 2 h and then cooled in water and liquid nitrogen. In addition it has been found by X-ray diffraction that the heat treatments applied did not change the types of the phases, but caused lattice deformations in the phases. Furthermore, beside ferrite and austenite, Laves, sigma, G, mu, R, chi, Fe3C, Fe3P, FeS2, MnS phases and M23C6, M7C3, M6C carbides were determined to be in the microstructure. DSC (differential scanning calorimeter) curves showed that some stoichiometry compounds of small amounts occurred between 370 and 470 degrees C, and in specimens cooled in liquid nitrogen after annealed at 950 degrees C for 2 h, a phase with a small percentage dissolving at about 310 degrees C. DTA (differential thermal analysis) curves also showed that austenite phase transformed to ferrite phase completely between 1182 and 1220 degrees C. In addition, it was found that the hardness of the specimens were different. (C) 1997 Elsevier Science S.A.
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    Investigation of the microstructures of iron based wrought Cr-Ni-Mo duplex alloy
    (Elsevier Science Sa Lausanne, 1997) Kuzucu, V; Ceylan, M; Aksoy, M; Aksoy, I; Kaplan, M
    Samples of duplex stainless steel, consisting of iron-based Cr-Ni-Mo ahoy containing some other elements undergoing various heat treatments after having been wrought at 1150 degrees C, have been investigated using X-ray diffraction, thermal analysis and metallographic techniques. It is determined that some intermetallic phases such as Laves, mu, G, mu, R, chi, and some carbide phases as such M23C6, M7C3, M6C may be found in these samples and that the ratio of carbide phases decreased in samples annealed at 950 degrees C. In samples cooled in liquid nitrogen, it is seen that some dissolving elements in the matrix have accumulated around the sigma phases and some precipitation phases have occurred. It is concluded that the use of annealing of this material at 950 degrees C affects the chemical, mechanical and other properties adversely. (C) 1997 Elsevier Science S.A.