Ironcarbon diagram and its reactions engineeringnotes4u. Ironcarbon phase diagram to refine steel from either scrap or pig iron, the amount of carbon must be carefully controlled. However, ductility is loss martensite is too brittle and a post heat treatment is. In this section, we are going to consider the most important alloy system in iron and steel. Ttt diagram indicates a specific transformation starts and ends and it also shows what percentage of transformation of austenite at a particular temperature is achieved. Note that pearlite is not a single substance, but rather a fine mixture of ferrite essentially pure iron and cementiteiron carbide a chemical compound of iron and carbon. In their simplest form, steels are alloys of iron fe and carbon c, so we will be looking at phase transformations using the fec phase diagram. Iron carbon diagram hindigate 2019 mechanical engg. The reason why the ironcarbon alloy is the basic alloy system in iron and steel is that the carbon is closely related with the process to make iron from the iron ore in the blast furnace operation which extracts the molten iron from the iron ore. It provides an invaluable foundation on which to build knowledge of both carbon steels and alloy steels, as well as a number of various heat treatments they are usually subjected to hardening, annealing. The alloy may constituent affect its colour while fractured.
The study of fec system is thus, important, more so as it forms the basis of commercial steels and cast irons, and many of the basic features of this system influence the behaviour of even the most complex alloy steels. The frozen eutectic has a composition of austenite solid solution of composition e and iron carbide. The ironiron carbide phase diagram heat treatment of steel features microstructures steels microstructural changes in steel on cooling for different compositions. Iron carbon phase diagram with eutectoid, eutectic. A slightly more colorful version of the ironcarbon phase diagram follows. Equilibrium phase diagrams the iron carbon diagram notes free download as powerpoint presentation. This helps us to understand how this control is done. The ironcarbon diagram also called the ironcarbon phase or equilibrium diagram is a graphic representation of the respective microstructure states depending on temperature y axis and carbon content x axis. Ironiron carbide phase diagram material engineering. The study of the constitution and structure of iron and steel start with the ironcarbon phase diagram. Material science, the iron carbon phase diagram, part 1 duration.
In their simplest form, steels are alloys of iron fe and carbon c. It is the hardest structure that appears on the diagram, exact melting point unknown. Download iron carbon phase diagram pdf at the end of. Phase diagrams definitions and basic concepts phases and microstructure binary isomorphous systems complete solid solubility binary eutectic systems limited solid solubility binary systems with intermediate phasescompounds the ironcarbon system steel and cast iron. Simplified iron carbon phase diagram austenite pearlite mixture of. Cast iron is an alloy of carbon and iron and other alloying elements e. Austenite is a primary solid solution based on j iron having fcc structure. Carbon is the most common alloying element in the iron which significantly affects the allotrophy, structure and properties of iron. Conventionally, the complete fe c diagram should extend from 100% fe to 100 % carbon graphite, but it is normally studied upto 6. A study of the constitution and structure of all steels and irons must first start with the ironcarbon equilibrium diagram. Phase diagrams metastable ironcarbon fec phase diagram. These diagrams define the regions of the stability of a phase which can exist in an alloy system under the.
The main structures, significance of various lines and critical points are discussed as. This is a fairly complex phase diagram but we are only interested in the steels part of. Teach yourself phase diagrams university of cambridge. Bainite a combination of ferrite and cementite in ferrous metals that is harder than pearlite. The study of the constitution and structure of iron and steel start with the iron carbon phase diagram. Timetemperaturetransformation ttt curves ttt diagram is a plot of temperature versus the logarithm of time for a steel alloy of definite composition. Ph8251 materials science syllabus notes question bank with. Iron carbon equillibrium diagram notesgen notesgen.
Classification, properties and uses of carbon steels, cast iron and. Carbon is the most important alloying element in iron which significantly affects the allotropy, structure and properties of iron. In their simplest form, steels are alloys of iron fe and. The fec phase diagram is a fairly complex one, but we will only consider the steel part of the diagram, up to around 7% carbon. The ironcarbon equilibrium diagram phases, invariant reactions microstructure of slowly cooled steels eutectoid steel, hypo and hypereutectoid steels effect of alloying elements on the fec system diffusion in solids ficks laws phase transformations tttdiagram for eutectoid steel pearlitic, baintic and martensitic. Note that carbon lowers the freezing point of iron and that it broadens the tempera. Before solidification freezing can occur the temperature must fall to a point on the lines ab or bc the iron carbon eutectic contains the equivalent of 4. Higher solubility of carbon in austenite is property of fcc structure and corresponding interstitial sites. The iron carbon phase diagram there is more to the ironcarbon phase diagram than related in the backbone. Dmitri kopeliovich ironcarbon phase diagram describes the ironcarbon system of alloys containing up to 6. This austenite transforms to pearlite upon slow cooling through the eutectoid temperature. The percentage of carbon determines the type of the ferrous alloy.
The ironiron carbide fefe3c phase diagram in their simplest form, steels are alloys of iron fe and carbon c. Ironcarbon diagram the influence of carbon rime gmbh. Iron carbon diagram leaving certificate engineering notes. On this diagram, the carbon percentage is shown on the xaxis and temperature on the yaxis. Detailed notes on iron iron carbon equilibrium diagram. The study of the ironcarbon fec binary phase diagram figure 1 is usually the start of a study for the microstruction of all steels. The ironcarbon diagram provides a valuable foundation on which to build knowledge of both plain carbon and alloy steels in their immense variety.
However, carbon present greatly influences the mechanical properties of. The ironcarbon phase diagram the phase diagrams are very important tools in the study of alloys for solutions of many practical problems in metallurgy. Presentation mode open print download current view. Invariant reactions in fec system true equilibrium diagram. So, apart from fefe3c diagram, your concepts in heat treatment may be weak.
Iron carbon alloys metallurgy engineering reference. Due to the high lattice distortion, martensite has high residual stresses. It is also the basic understanding of the heat treatment of steels. During the casehardening process, a lowcarbon steel either straight carbon steel or lowcarbon alloy steel is heated to a.
Ironcarbon phase diagram in their simplest form, steels are alloys of iron fe and carbon c. Introduction to ironcarbon equilibrium diagram structures in fec diagram ironcarbon equilibrium diagram fig. Iron carbon diagram presentation linkedin slideshare. This graph, which is known as iron carbon equilibrium diagram has the following important points. On the basis of ironcarbon diagram, we can divide ironcarbon alloys into three distinct categories like cast irons, steels, cast steels. It provides an invaluable basis upon which both carbon steels and alloy steels as well as various heat therapies are usually subject to. In particular, there is some nomenclature that i avoided in the main text but that is important for understanding other writings about iron and steel. Now, we consider only a part of fefe3c diagram referring to steel.
Iron carbon phase diagram with detailed explanation. Alloys and phase diagram interview question and answers. The fefe3c diagram is not the easiest thing to understand. A study of the microstructure of all steels usually starts with the metastable ironcarbon fec binary phase diagram figure 1. Equilibrium phase diagrams the iron carbon diagram notes.
The ironcarbon equilibrium diagram total materia article. When molten cast iron solidifies some of the carbon precipitates as graphite, forming tiny, irregular flakes within the crystal structure of the metal. The high lattice distortion induces high hardness and strength to the steel. Ironcarbon phase diagram explained with graphs fractory. The actual ironcarbon diagram is far larger than the part shown here. Thus, each vertical dashed line, like the solid line in fig. Iron carbon phase diagram in their simplest form, steels are alloys of iron fe and carbon c. At this point it is important to note that far more carbon can be absorbed in the gamma mixed crystal. The percentage of carbon present and the temperature define the phase of the iron carbon alloy and therefore its physical characteristics and mechanical properties.