### Uddeholm AEB-L Stainless Steel

AEB-L is a conventionally ingot-cast martensitic stainless steel designed and manufactured by Uddeholm Tooling AB (Sweden). Its nominal chemical composition (in weight percent) is as follows:

C = 0.65
Cr = 12.8
Si = 0.4
Mn = 0.65

Figure 1 shows the phase diagram of Uddeholm AEB-L stainless steel (in deg. Celsius) calculated with Thermo-Calc, coupled with TCFE3 thermodynamic database.

Figure 1. Phase diagram of Uddeholm AEB-L stainless steel (in deg. Celsius) calculated with Thermo-Calc, coupled with TCFE3 thermodynamic database. Silicon and manganese were excluded from thermodynamic calculations.

The equilibrium values for solidus and liquidus temperatures were calculated to be 1461 °C (2661 °F) and 1379 °C (2515 °F), respectively.

In the temperature range of 1144-1379 °C (2091-2515 °F) the microstructure of Uddeholm AEB-L stainless steel consists of just one single phase: austenite. Thus, if AEB-L steel is hardened from an austenitization temperature that is higher than 1144 °C (2091°F) the resulting martensitic microstructure will contain no primary carbides.

Below the temperature of 1144 °C (2091 °F) the chromium-rich M7C3 primary carbides start to precipitate from the austenitic matrix. At the austenitization temperature of, say, 1052 °C (1925 °F) the equilibrium amount of chromium-rich M7C3 primary carbides is 3.3 molar percent (2.6 volume percent). The equilibrium amount of carbon and chromium in the austenitic matrix at 1052 °C (1925 °F) is 0.44 wt. % and 11.4 wt. %, respectively. (The amount of carbon and chromium in the matrix is a good indicator of the steel's hardenability and corrosion resistance, respectively.)

The equilibrium value for A1 temperature (eutectoid temperature) was calculated to be 814 °C (1497 °F). Under equilibrium conditions the austenite in Uddeholm AEB-L stainless steel transforms into ferrite at this temperature.