In this video we deal with steels as the most important alloy in mechanical engineering, consisting of iron and carbon. We will explain the phase diagram relevant for steels, which is also referred to as the iron-carbon phase diagram (steel part). In this context, we discuss in more detail the stable system with its graphite precipitation, which is relevant for cast irons, and the metastable system with its cementite precipitation (Fe3C), which is relevant for steels. We will also explain the determination of microstructural components such as ferrite and pearlite or grain boundary cementite for hypereutectoid, eutectoid and hypoeutectoid steels.
00:00 Iron, steel and cast iron
00:43 Cooling curve of soft iron (pure iron)
02:34 Creating iron-carbon phase diagram
03:45 Lattice transformation & solubility
05:34 Complete iron-carbon phase diagram
08:00 Solidification of steels
09:03 Gamma-Alpha lattice transformation (austenite into ferrite)
10:25 Stable system (precipitation of graphite in cast iron)
11:36 Metastable system (precipitation of cementite in steels)
13:34 Stable and metastable phase diagram in comparison
14:28 Complete cooling curve of soft iron (delta-iron)
16:47 Microstructure transformation of steels
19:27 Eutectoid steel
21:09 Solubility of carbon in austenite (gamma-iron)
22:55 Hypereutectoid steel
24:50 Approaching the eutectoid composition
26:31 Hypoeutectoid steel
28:13 Approaching the eutectoid composition
29:47 Summary
32:18 Determination of the microstructure proportions (hypoeutectoid steel)
34:55 Determination of the phase fractions (hypoeutectoid steel)
36:12 Determination of the microstructure proportions (hypereutectoid steel)
37:07 Determination of the phase fractions (hypereutectoid steel)
37:44 Microstructure diagram
