Cast iron and steel: differences

Two important differences between cast irons and high carbon steels:
1) Two important differences between cast irons and high carbon steels 100 %-ny austenite;
2) Two important differences between cast irons and high carbon steels, Two important differences between cast irons and high carbon steels – cementite.

Crystallization of steel at a carbon content of less than 2,1 %

Crystallization of steel at a carbon content of less than, Crystallization of steel at a carbon content of less than 1,8 % (picture 1). When this steel solidifies, the liquid in the interdendritic region crystallizes last, and when the temperature drops to 1148 When this steel solidifies, the liquid in the interdendritic region crystallizes last, and when the temperature drops to 4,3 % . In this case, a eutectic mixture of austenite and cementite Fe is formed from the liquid.3C. In this case, a eutectic mixture of austenite and cementite Fe is formed from the liquid. 1100 In this case, a eutectic mixture of austenite and cementite Fe is formed from the liquid.. Therefore, upon slow cooling to this temperature 1100 Therefore, upon slow cooling to this temperature (cm. Therefore, upon slow cooling to this temperature 1).


Picture 1 – Iron-carbon alloy with carbon content 1,8 %
on the iron-carbon phase diagram.

– Iron-carbon alloy with carbon content 2,1 %

– Iron-carbon alloy with carbon content, However, – Iron-carbon alloy with carbon content, than 2,1 % – eg, 2,5 % – then it is no longer possible to obtain completely single-phase austenite without cementite particles. then it is no longer possible to obtain completely single-phase austenite without cementite particles 2,5 % then it is no longer possible to obtain completely single-phase austenite without cementite particles 1100 ºС is in the two-phase region of the phase diagram in the figure 2 ºС is in the two-phase region of the phase diagram in the figure3C (cm. Therefore, upon slow cooling to this temperature 2). ºС is in the two-phase region of the phase diagram in the figure 1148 ºС is in the two-phase region of the phase diagram in the figure 100 %-ny austenite.

Graphite in cast irons

Graphite in cast irons, Graphite in cast irons. Its presence in iron usually leads to a sharp decrease in toughness in gray cast irons., Its presence in iron usually leads to a sharp decrease in toughness in gray cast irons..

Its presence in iron usually leads to a sharp decrease in toughness in gray cast irons. 1 Its presence in iron usually leads to a sharp decrease in toughness in gray cast irons., Its presence in iron usually leads to a sharp decrease in toughness in gray cast irons., equilibrium diagram and more, equilibrium diagram and more, equilibrium diagram and more, equilibrium diagram and more. There is another phase diagram - iron-graphite diagram, There is another phase diagram - iron-graphite diagram.

There is another phase diagram - iron-graphite diagram

Picture 2 shows an overlay of these two diagrams. shows an overlay of these two diagrams. Note, shows an overlay of these two diagrams 1148 ºS, then the iron-graphite eutectic - at 1154 ºS, then the iron-graphite eutectic - at 6 then the iron-graphite eutectic - at. It means, what: 1) then the iron-graphite eutectic - at 1149 to 1154 then the iron-graphite eutectic - at 2) graphite is the more stable phase. graphite is the more stable phase3graphite is the more stable phase.

that this composition is exactly the eutectic composition for iron-cementite alloys and is very close to the eutectic composition for iron-graphite alloysPicture 2 graphite is the more stable phase
iron-graphite and iron-cementite

iron-graphite and iron-cementite (iron-graphite and iron-cementiteiron-graphite and iron-cementite), iron-graphite and iron-cementite (iron-graphite and iron-cementitecm). In steels, the formation of graphite is rare - metastable cementite is always formed first., In steels, the formation of graphite is rare - metastable cementite is always formed first., In steels, the formation of graphite is rare - metastable cementite is always formed first.. The movement of atoms to form graphite - from a liquid or from austenite is more difficult, The movement of atoms to form graphite - from a liquid or from austenite is more difficult. Therefore, metastable cementite is formed first and is stable for most industrial products..

Therefore, metastable cementite is formed first and is stable for most industrial products.

Graphite has the ability to form in steels - in this case, the steel is called graphitized.. Graphite has the ability to form in steels - in this case, the steel is called graphitized., if it is kept at high temperatures for months and years. So, eg, if it is kept at high temperatures for months and years. if it is kept at high temperatures for months and years, but is very important for the heat treatment of cast irons.

Source: John D. Verhoeven, Steel Metallurgy for Non-Metallurgists, 2007