Investigation of Thermally Induced Deterioration Processes in Cold Worked SAF 2507 Type Duplex Stainless Steel by DTA

Abstract

Thermally induced deterioration processes were studied in cold worked (up to 60% deformation) SAF 2507 type super-duplex stainless steel (SDSS) by differential thermal analysis (DTA). DTA results revealed two transformations. Parent and inherited phases of these transformations were examined by other methods too, such as micro-hardness tests, optical metallography and X-ray diffraction (XRD). Finally, these transformations were identified as the formation of α’- and σ-phases. Formation of strain-induced martensite (SIM) and recrystallization were not experienced until 1000 °C, despite high degree of cold working. Activation energies of the σ-phase precipitation and α’-phase formation were determined from the Kissinger plot, through DTA measurements—they are 275 and 220 kJ/mol, respectively—in good agreement with the values found in the literature.

Microstructure and Corrosion Properties of Austenitic and Duplex Stainless Steel Dissimilar Joints

“…Duplex stainless steels have great strength (yield strength, R p0.2 ≈ 500 MPa) and excellent corrosion resistance especially against stress corrosion [1][2][3][4][5]. Thus, the application of duplex stainless steels (DSSs) in civil engineering, chemical, oil and gas industries are constantly growing [6][7][8][9].…”