ABSTRACT
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Iron-based alloys account for a large portion of all metals production. The range of compositions and microstructures of iron-based alloys is far wider than any other system. Pure iron is soft and ductile. Development of scratch-free and deformation-free grain structures is difficult. Sheet steels present the same problem, which can be complicated by protective coatings of zinc, aluminum, or Zn-Al mixtures. In general, harder alloys are much easier to prepare. Cast irons may contain graphite, which must be retained in preparation.
Inclusions are frequently evaluated and quantified. Volume fractions can vary from nearly 2% in a free-machining grade to levels barely detectable in a premium, double-vacuum melt alloy. A wide range of inclusion, carbide, and nitride phases has been identified in steels. Addition of 12% or more chromium dramatically reduces the corrosion rate of steels, producing a wide range of stainless steel alloys. Tool steels cover a wide range of compositions and can attain very high hardnesses. Preparation of ferrous metals and alloys is quite straightforward using contemporary methods. Edge retention and inclusion retention are excellent, especially if automated equipment is used.
