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
玻璃杯的英文>什么是有价证券Mn = 0.65
Figure 1 shows the pha diagram of Uddeholm AEB-L stainless steel (in deg. Celsius) calculated with Thermo-Calc, coupled with TCFE3 thermodynamic databa.
Figure 1. Pha diagram of Uddeholm AEB-Lpopcorn是什么意思 stainless steel (in deg. Celsius) calculated with Thermo-Calc, coupled with TCFE3 thermodynamic databa. Silicon and mangane 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 pha: 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.)
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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.
Finally, plea e additional information about the Fe-Cr-C ternary pha diagrams.
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• Pha diagram (in deg. Celsius) of Uddeholm AEB-L stainless steel
• Pha diagram (in deg. Fahrenheit) of Uddeholm AEB-L stainless steel
Martensitic stainless steel such as 154CM contains about 4 wt. percent molybdenum (in addition to 1.05 wt. % C and 14.0 wt. % Cr). To determine the effect of 4 wt. % Mo on the Fe-Cr-C ternary system, consider Figures 5 and 6, which show the isothermal ctions of Fe-4Mo-Cr-C quaternary pha diagram at 1000°C (1832°F) and 1100°C (2012°F), respectively.
Figure 5.remove什么意思 Isothermal ction of Fe-4Mo-Cr-C quaternary pha diagram at 1000°C (1832°F) calculated with Thermo-Calc coupled with TCFE2000 thermodynamic databa.
According to Thermo-Calc calculations, the austenitic matrix of Fe-4Mo-14Cr-1.05C alloy at 1000°C (1832°F) has the following chemical composition (in weight percent):
Cr = 8.6
C = 0.33
Mo = 2.6
The amount of chromium-rich M23C6教育部雅思报名 primary carbides in Fe-4Mo-14Cr-1.05C alloy at 1000°C (1832°F) is calculated to be 16.8 mol. percent. It is worth noting that the addition of 4 wt. % Mo to the Fe-Cr-C system expands significantly the prence of M23C6 pha at the expen of the M7C3 pha (compare Figure 1 — Isothermal Section of Fe-Cr-C T
ernary Pha Diagram at 1000°C — and Figure 3 — Isothermal Section of Fe-0.8Mo-Cr-C Quaternary Pha Diagram at 1000°C — with Figure 5).
Figure 6. Isothermal ction of Fe-4Mo-Cr-C quaternary pha diagram at 1100°C (2012°F) calculated with Thermo-Calc coupled with TCFE2000 thermodynamic databa.
According to Thermo-Calc calculations, the austenitic matrix of Fe-4Mo-14Cr-1.05C alloy at 1100°C (2012°F) has the following chemical composition (in weight percent):
Cr = 10.6
C = 0.58
Mo = 3.4
The amount of chromium-rich M23C6 primary carbides in Fe-4Mo-14Cr-1.05C alloy at 1100°C (2012°F) is calculated to be 11.6 mol. percent.
The amount of chromium and molybdenum in the matrix is also an indicator of the con
dary-hardening respon — in general, the higher the amount of chromium and molybdenum in the matrix, the stronger the condary-hardening respon during tempering (especially at higher tempering temperatures.)
Part 1: Fe-Cr-C Ternary Pha Diagrams
Part 2: Fe-0.8Mo-Cr-C Quaternary Pha Diagrams
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A high hardness level, a fine array of uniformly distributed primary alloy carbides, and an adequate matrix chromium content are the three most desired properties required to produce a knife with optimum properties. Ideally, a martensitic stainless steel grade for knife applications should, therefore, satisfy the following two fundamental requirements:
(1) The carbon content of the austenitic matrix has to be around 0.6 wt. pct. or higher in order to achieve the hardness of 63-64 HRC.
盘缠(2) The chromium content of the austenitic matrix has to be at least 12 wt. pct. in order to ensure corrosion resistance. (It should be said, however, that a part of matrix chromium can be replaced with molybdenum with little or no negative conquences for corrosion resistance.)
Isothermal ctions of the Fe-Cr-C ternary pha diagram are a good starting point when it comes to understanding the various trade-offs between the austenitization temperature lected for heat treatment and the resulting chemical composition of the austenitic matri
x.
The composition plane for the Fe-Cr-C ternary pha diagram at 1000°C (1832°F) is shown on Figure 1. The carbon content is plotted along the horizontal axis and the chromium content along the vertical axis of the composition plane.
Figure 1. Isothermal ction of Fe-Cr-C ternary pha diagram at 1000°C (1832°F) calculated with Thermo-Calc coupled with TCFE2000 thermodynamic databa.
The isothermal ction in Figure 1 shows the content of chromium and carbon in the various phas of Fe-Cr-C alloys that can exist at 1000°C (1832°F). The area labeled γ (the Greek letter gamma) reprents austenite. If the composition of an Fe-Cr-C alloy is plotted on Figure 1 and it falls inside the γ area, the microstructure of that alloy will consist of austenite only, i.e., no carbides will be prent at 1000°C (1832°F).
Consider now one of the most basic martensitic stainless steel grades such as AISI 440C (approximately 17 wt. pct. chromium and 1.075 wt. pct. carbon), plotted on the composition plane of Figure 1. Its chemical composition falls inside of the region labeled γ + M7C3. This means that if AISI 440C is heated to 1000°C (1832°F) its microstructure will consist of austenite and chromium-rich M7C3 primary carbides. Upon quenching the 我也爱你英文
martensite formed from the austenite will contain chromium-rich M7C英文名测试3 primary carbides disperd within it.
It is worth noting that on Figure 1 the right-hand boundary of the austenite region is labeled "Carbon Saturation Line". This line is important as it tells us the maximum amount of carbon that austenite can dissolve within itlf — addition of more carbon would precipitate carbides.
The further the alloy composition lies to the right of the saturation line, the larger the volume fraction of chromium-rich M7C3 primary carbides it will contain. The prence of chromium-rich M7garionC3 primary carbides renders the austenite depleted in both chromium and carbon relative to the overall chemical composition of the alloy.
Figure 1 can be ud to determine the chemical composition of the austenite in an alloy such as AISI 440C. The austenite composition for AISI 440C at 1000°C (1832°F) is found
at the point where the tie line drawn through AISI 440C intercts the carbon saturation line. It is worth noting that even though AISI 440C alloy contains 1.075 percent of carbon and 17 percent of chromium overall, the austenite that forms at 1000°C (1832°F) contains only around 0.3 percent of carbon and 11.7 percent of chromium (e Figure 1). The martensite that forms upon quenching has the same chemical composition as the austenite. The carbon and chromium contents of the martensite have, in turn, the effect on its hardness and corrosion resistance, respectively. Thus, AISI 440C martensitic stainless steel, when hardened from 1000°C (1832°F), does not satisfy the two requirements stated above (the carbon and chromium content of the matrix of at least 0.6 and 12 percent, respectively).
To demonstrate the effect of increasing the austenitization temperature on the volume fraction of primary carbides and the chemical composition of the austenite, consider the change in the position of the carbon saturation line in Figure 2.
Figure 2. Isothermal ction of Fe-Cr-C ternary pha diagram at 1100°C (2012°F) calculated with Thermo-Calc coupled with TCFE2000 thermodynamic databa.
When the austenitization temperature is incread from 1000°C (1832°F) to 1100°C (2012°F), the content of carbon and chromium in the austenitic matrix is incread from 0.3 % C / 11.7 % Cr to 0.5 % C / 13.2 % Cr. The volume fraction of chromium-rich M7C3 primary carbides is smaller at 1100°C (2012°F) than at 1000°C (1832°F), as graphically demonstrated by the length of the tie line in Figures 1 and 2.
The Second Edition of Heat Treater's Guide — Practice and Procedures for Irons and Steels (published by ASM International in 1995) recommends that AISI 440C be austenitized at 1010°C-1065°C (1850°F-1949°F). For maximum corrosion resistance and strength, the Guide recommends the upper end of the austenitization range. Such a recommendation is not surprising. The above given pha diagrams demonstrate that the
higher austenitization temperatures will increa both the carbon and chromium contents of the austenitic matrix.
It is worth noting that the matrix of AISI 440C martensitic stainless steel does not simultaneously satisfy the 0.6 % C and 12 % Cr requirements, even at 1100°C (2012°F). Not surprisingly, AISI 440C is typically hardened to just 58-60 HRC.
Finally, the Fe-Cr-C ternary pha diagrams explain — at least in part — why some commercial martensitic stainless steel grades, such as Sandvik 12C27 (Fe-0.6C-13.5Cr) and Uddeholm AEB-L (Fe-0.65C-12.8Cr), are in general considered to be well optimized for stailess knives.
Part 2: Fe-0.8Mo-Cr-C Quaternary Pha Diagrams
Part 3: Fe-4.0Mo-Cr-C Quaternary Pha Diagrams
