Ans from ttt diagrams below 1 austenite transform to 100% bainite. This lecture discusses the iron carbon phase diagram with different phases and reactions involved. According to the diagram, point b is which of the following. Nptel provides elearning through online web and video courses various streams. The high lattice distortion induces high hardness and strength to the steel. Interstitial elements like carbon added in the form of graphite diffuse very rapidly in iron, while substitutional elements like nickel, copper and molybdenum diffuse much more slowly. This video introduces major features of the fefe3c phase diagram, steel classification, and basics applications for steels. Match the expected phases present at points a,b,c,e,f with the schematic. The fec phase diagram is a fairly complex one, but we will only consider the steel part of the diagram, up. Mod01 lec23 ironcarbon phase diagram video lecture by prof. Binary systems have two components, ternary systems three, and so on. Mar 11, 20 the iron carbon phase diagram the phase diagrams are very important tools in the study of alloys for solutions of many practical problems in metallurgy. As the number of co moles per fe atom is a figure 2.
Understanding different types of carbon and low alloy steels, stainless steels. The effects of carbon on certain characteristics of pure iron are shown in fig. If the percentage of the carbon is in the range of 0 to 2. White and malleable cast irons the lowsilicon cast irons iron is an intermediate for the production of malleable iron. It is primarily associated with mild steels having a high carbon content and a ferriticpearlitic microstructure. Alloys of iron and carbon the properties of iron are affected. Iron carbon phase diagram iron shows a eutectic with carbon allowing for a lower melting alloy body centered tetragonal. Notice that austenite can dissolve much more carbon than ferrite.
Blast furnace as an efficient counter current gas solid reactor and maximum carbon efficiency. Iron carbon phase diagram explanation in detail iron. Free cementite is found in all steel containing more than 0. A binary alloy contains two components, a ternary alloy three, etc. A detailed information about iron carbon phase diagram with eutectoid, eutectic, peritecti, peritectoid phase transformations are presented in a detailed way. The fefe3c phase diagram is the basis of steels and cast irons. Ironcarbon diagram explanation pdf mechanical enotes. Teach yourself phase diagrams and phase transformations. Nptel metallurgy and material science principles of. The amount of carbon present in an iron carbon alloy, in weight percent, is plotted on the xaxis and temperature is plotted on the yaxis. Pure iron upon heating exhibits two allotropic changes as shown below. Example 2 using the isothermal transformation diagram for an iron carbon alloy of eutectoid composition, specify the nature of the final microstructure of a. Cementite or iron carbide is an interstitial compound of iron and carbon.
Compulsory, 2 marks will be given from this iron carbon diagram theory in any exam. Ghosh, dept of metallurgical and materials engineering. Section ii the cfe carbon iron system by ho okamoto asm international equilibrium diagram the number of experimental and theoretical publications on the fec phase diagrams and related subjects is virtually unlimited because of the unqueslionable importance of fec alloys in all as. The phase diagram of an alloy made of components a and b, for all combinations of t and wb or xb, defines the ab system. Pdf design of steel structures subramanian narayanan. Mod01 lec23 ironcarbon phase diagram tutorial of principles of physical metallurgy course by prof r. Ghosh,department of metallurgy and material science,iit kharagpur. Please refer to the following diagram and answer 15 questions consider alloys 1 and 2. Fec equilibrium diagram austenite is stable above a1 temperature below this temperature. Iron carbon phase diagram with detailed explanation.
During corrosion of such steel, the ferrite phase dissolves and a porous iron carbide network is exposed see fig. Iron carbon phase diagram in their simplest form, steels are alloys of iron fe and carbon c. Thus, this diagram see bottom most horizontal line in fig. Parts 24 show you how to read and interpret simple phase diagrams, describe the important ironcarbon phase diagram, and give examples of. Engineering materials and metallurgy course matrial. Iron carbide fe 3 c is often labeled as the uncorroded portion of the steel. It should be realized that gramin discussing iron carbcn al loys, we actually are dealing with plain carbon steels and cast irons. Information about the portion of the ironacarbon alloy system which is of interest to engineers, ironairon carbide equilibrium diagram is given in this article. In their simplest form, steels are alloys of iron fe and. Iron carbide equilibrium diagram material science engineers academyhello everyone welcome to aim amiein this videos we have covered the iron carbon equil. Time temperature transformation ttt diagrams phase. It has the lowest hardness but the highest ductility.
Iron carbide fe3c an overview sciencedirect topics. Overall heat and material balance in blast furnace. A phase diagram or equilibrium diagram is a diagram with t and composition as axes, showing the equilibrium constitution. Ferrite or a iron up to 910c dissolves carbon in an interstitial solid solution to a maximum of 0. Introduction to materials science chapter 9, phase diagrams 2 component chemically recognizable species fe and c in carbon steel, h2o and sucrose in sugar solution in water.
Module 23 iron carbon system i lecture 23 iron carbon system i. For example, the phases found in the simple binary fec system. Review fec phase diagram 2 important pointseutectoid b. Pure iron at room temperature consists of grains of ferrite. Allotropic changes, ironiron carbide equilibrium diagram, phases, invariant reactions, critical. Assuming that the alloying element consists of small spherical particles randomly dispersed in a dense iron matrix, the time t p. Section ii the cfe carbon iron system by ho okamoto asm international equilibrium diagram the number of experimental and theoretical publications on the fec phase diagrams and related subjects is virtually unlimited because of. Cementite, chemical formula fe3c has a fixed carbon content of 6. Iron carbon thephase diagram the complete ironiron carbon phase or consti tutional diagram. Using the isothermal transformation diagram for an iron carbon alloy of eutectoid composition figure 10. Phase diagrams study notes for mechanical engineering. It is an interstitial solid solution of a small amount of carbon dissolved in.
Kinetics of reduction and oxidation reactions during. This graph, which is known as iron carbon equilibrium diagram has the following important points. The fec phase diagram is a fairly complex one, but we will only consider the steel and cast iron part of the diagram, up to 6. These diagrams define the regions of the stability of a phase which can exist in an alloy system under the condition of constant atmospheric pressure.
Phase a portion of a system that has uniform physical and chemical characteristics. In their simplest form, steels are alloys of iron fe and carbon c. Carbon present in solid iron as interstitial impurity, and forms solid solution with ferritesaustenite as depicted by three single fields represented by. Various routes of modern steel making bfbof, drieaf, sr. Cementite is a chemical compound of carbon with iron and is known as iron carbide fe3c. However, ductility is loss martensite is too brittle and a post heat treatment is.
Practical maintenance blog archive the ironiron carbide. Thomson learning is a trademark used herein under license. When solidification starts, austenite is formed from the liquid. At 1147c, the solidification of austenite is complete as observed in an iron carbon diagram. For steels, solution annealing involves heating to a sufficiently. Ghosh, dept of metallurgical and materials engineering 2 keywords. Module 24 iron carbon system ii lecture 24 iron carbon system ii 1 nptel phase ii. On the basis of this diagram iron carbon alloys having less than 2. Slide 2 presents a sketch of iron carbon phase diagram. Dmitri kopeliovich ironcarbon phase diagram describes the iron carbon system of alloys containing up to 6. Phase diagrams in materials science and engineering.
C metastable equilibrium diagram and ttt diagrams for plain carbon hypoeutectoid, eutectoid and hypereutectoid steels. Recall that it tells us about the structure of alloys under equilibrium rate of cooling. Due to the high lattice distortion, martensite has high residual stresses. It is the softest structure that appears on the diagram. The upper limit of the ferrite cementite phase field horizontal line going through the eutectoid point. Iron graphite phase diagram, morphology of graphite in cast iron, grey cast iron, malleable cast iron, nodular cast iron, mechanical properties of iron. However, if the cooling is slow, graphite flakes are formed. It is the hardest structure that appears on the diagram, exact melting point unknown. Iron carbon phase diagram an example of a commonly used phase diagram is the iron carbon phase diagram, which is used to understand the phases present in steel. Given that iron carbide is an electronic conductor, this porous network serves as. Nov 18, 20 the cct diagram solid lines for a 1080 steel compared with the ttt diagram dashed lines. Especially notice that at 727oc the ferrite can dissolve only 0.
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