Prediction and measurement of selected phase transformation temperatures of steels

Abstract

The study deals with precise determination of phase transformation temperatures of steel. A series of experimental measurements were carried out by Differential Thermal Analysis (DTA) and Direct Thermal Analysis (TA) to obtain temperatures very close to the equilibrium temperatures. There are presented results from the high temperatures region, above 1000 °C, with focus on the solidus temperatures (T S), peritectic transition (T P) and liquidus (T L) of multicomponent steels. The data obtained were verified by statistical evaluation and compared with computational thermodynamic and empirical calculations. The calculations were performed using 15 empirical equations obtained by literature research (10 for T L and 5 for T S), as well as by software InterDendritic Solidification (IDS) and Thermo-Calc (2015b, TCFE8; TC). It was verified that both thermo-analytical methods used are set correctly; the results are reproducible, comparable and close to equilibrium state.

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

“…Table 5 shows the deviation obtained between the experimental [22,[82][83][84]87,92,95,[109][110][111] and calculated austenite formation temperatures for 25 low-alloyed and 28 high-alloyed (stainless) steels. The average deviation between the calculated and the measured temperatures was 7.0 °C.…”

“…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.…”

“…From all phase‐change temperatures, the liquidus temperature can be most accurately measured. Table 2 and 3 show the average deviation () obtained between the experimental [ 22,37–112 ] and calculated liquidus temperatures for 283 ternary Fe–X–C alloys (Table 2), 274 ternary Fe–Cr–X and Fe–Ni–X alloys (Table 2), 55 ternary Fe–X–Y alloys (Table 2 ), as well as 410 low‐alloyed (143) and high‐alloyed (267) steels (Table 3). The average deviations in the predicted liquidus temperatures are 5.6 °C for carbon alloys, 3.9 °C for Cr and Ni alloys, and 11.8 °C for other alloys (Table 2), while the average deviation for the low‐ and high‐alloyed steels was 3.2 °C (see Table 3).…”

Determination of phase transformation temperatures of 20MnCr5 steel using CompuTherm thermodynamic database and design of regression equations

“…Knowledge of the temperatures of the phase transformations of steel is very important either in its production or heat treatment. These temperatures allow us to understand the basic properties of steel, to determine the correct casting temperature or to optimize the settings of metallurgical processes [1][2][3].…”

“…The temperature range between the liquidus and solidus temperature determines the so-called two-phase zone, where the liquid phase changes to solid. Knowledge of the range allows prediction of steel tendency to internal defects, determination of steel liquidus temperature allows correct setting of steel casting temperature [2][3][4][5][6].…”