Thermodynamic calculation of phase equilibria in stainless steels

Abstract

In this paper two examples of thermodynamic investigation of stainless steels using both, experimental and modeling approach are described. The ferritic-austenitic duplex stainless steel and austenitic stainless steel were investigated using thermal analysis. The complex melting behavior was evident for both alloy systems. Experimentally obtained data were compared with the results of the thermodynamic calculations using the CALPHAD method. The equilibrium thermal events were also described by the calculated heat capacity. In spite of the complexity of both selected real alloy systems a relative good agreement was obtained between the thermodynamic calculations and experimental results

Effect of Microstructure on Thermophysical Properties of Heat-Treated Duplex Steel

“…The peak is greatest with a ferrite content of 75%. At approximately 900 • C the σ phase dissolves with other carbides and nitrides [13]. This effect occurs with any ferrite content, but is strongest with a ferrite content of 75%, and weakest with a ferrite content of 44%.…”

“…Precipitations of the alpha prime phase create very fine spherical zones, which at higher temperatures take the shape of disks parallel to the ferrite planes. The phenomenon of dispersion hardening at the temperature of 475 • C increases with the content of chromium in steel [7,10,[12][13][14][38][39][40]. At approximately 720 • C, there is a peak which corresponds to the calculated Curie temperature (706 • C) [13,14].…”

“…The phenomenon of dispersion hardening at the temperature of 475 • C increases with the content of chromium in steel [7,10,[12][13][14][38][39][40]. At approximately 720 • C, there is a peak which corresponds to the calculated Curie temperature (706 • C) [13,14]. The peak is greatest with a ferrite content of 75%.…”

“…Lecomte-Beckers et al [12] investigated the thermal characteristics of thermal diffusivity, thermal conductivity, specific heat and thermal expansion in DSS Uranus 76N non-rolled slabs in longitudinal and transversal directions. The temperature characteristics of the specific heat revealed reverse austenitic transformations appearing at 516 • C and at 1000 • C. Klancnik et al [13] compared DSC experimental data for SAF 2205 DSS and AISI 304 LN austenitic steel with the results of thermodynamic calculations using the CALPHAD (CALculation of PHAse Diagrams) method. Regarding the calculated heat capacity diagrams for both steels, relatively good agreement was obtained between the thermodynamic calculation and experimental results.…”

Simulation of the Solidification and Microstructural Evolution in Steel Casting Processes Using the InterDendritic Solidification Tool

“…Table 7 shows the deviation obtained between the experimental [22,52,82,84,[86][87][88]90,92,93,95,96,99,[102][103][104][105][106][107][108][109][110][111]128,[130][131][132] and calculated solidus temperatures for 75 low-alloyed and 103 high-alloyed (stainless) steels. The average deviation between the calculated and the measured temperatures is as high as 10.3 °C but due to the aforementioned poor accuracy in the measuring technique, the correlation can be considered reasonable.…”