LOGAM IRON (BAJA KARBON) PDF

Machine Translated by Google LOGAM IRON (FERROUS METAL) Machine Translated by Google Machine Translated by Google Many elements in the periodic table mix to form compounds with different...

Machine Translated by Google LOGAM IRON (FERROUS METAL) Machine Translated by Google Machine Translated by Google Many elements in the periodic table mix to form compounds with different properties and are used for different applications. Among these compounds is iron compound. But what is meant by iron? Iron compound is any material that contains iron in its composition. The word ferrous comes from the Latin word Ferrum, meaning iron. Some metals are formed from a mixture of iron and other elements. Metals are hard, shiny, opaque materials and have good electrical and thermal conductivity. There are two types of ferrous materials: ferrous metals and non-ferrous metals. Machine Translated by Google What is ferrous metal? Ferrous metal is a material formed by iron and its alloys. The most widely used metal due to its low extraction and acquisition costs. Iron is the second most abundant metal on Earth, and makes up 5% of the Earth's crust. Its existence is not in pure form, but in the form of iron oxide, Fe2O3 (hematite), Fe3O4 (magnetite). Pure iron has poor properties, so it is not widely used. Iron alloyed with carbon can improve its properties and make it useful in its applications. Machine Translated by Google Iron metal has physical, mechanical, and chemical properties, such as: The high iron content in its composition makes it cheaper than non- ferrous metals (because iron is abundant on Earth). Iron metal is heavy and has a high density and high melting temperature, so a special furnace is needed to melt it. Iron is a hard metal, making it useful for engineering applications, but it oxidizes easily and is therefore prone to rust. Iron metal is brittle, but conducts electricity, heat and is magnetic. Iron is easy to recycle. Machine Translated by Google Machine Translated by Google Steel is an alloy of iron and carbon. Steel is one of the most widely used construction materials due to its high tensile strength and acceptable compressive strength. used in skyscrapers, buildings, bridges, structures, railroads, and other applications other techniques. Carbon represents less than 0.35% of the mixture with iron. Steel is one of the most important materials in the construction industry Machine Translated by Google Carbon steel is an iron-carbon alloy with higher percentage of carbon in mixture and small concentration of manganese (Mn). This increases its tensile strength and decreases its toughness and ductility. It is used for the manufacture of machine elements, engines, vehicles, spare parts, pipes, and other uses. other. Carbon steel is used in pipes Machine Translated by Google Alloy steel is made of iron and carbon, with addition of various elements that function to improve physical, mechanical or chemical properties in particular. This blend achieves different results depending on the presence or absence of other metals. For example, adding manganese increases impact resistance. The addition of tungsten (W) produces steel that is resistant to high temperatures. Alloy steel is used to produce nuts Other materials used in alloy steel are and other machine parts. aluminum, sulfur, copper, chromium, nickel, silicon, and vanadium. Alloy steel is used for manufactures nuts and bolts, tools, and machine parts. Machine Translated by Google Steel is an alloy of iron with carbon and small amounts of other materials. The carbon content is usually less than 1.0 wt%. Based on carbon content, steel is divided into 3: a. low carbon steel, b. medium carbon steel, and c. high carbon steel. Machine Translated by Google Low carbon steel contains carbon 11wt%). - divided into three types: baja anti karat martensitic ferritic anti karat coating. austenitic anti karat coating - martensitic steel can be heat treated while ferritic and austenitic steel cannot. - strengthening of ferritic and austenitic stainless steels is carried out by cold working. - martensitic and ferritic stainless steels are magnetic while austenitic stainless steels are not. Machine Translated by Google Fe-Cr alloy is the simplest type of stainless metal with a basic ferrite structure. We can understand this by studying the Fe-Cr phase equilibrium diagram shown in the image on the side. Chromium is a ferrite stabilizer. Chromium with BCC structure (same as Ferrite) will expand the alpha phase region and narrow the gamma phase region. As a result, an Austenite loop is formed that limits the FCC and BCC regions. From Figure 3-15 it can be seen that in Fe-Cr alloys with Cr content above 12% there is no Austenite to Ferrite phase transformation. From room temperature to its melting point the phase is ferrite. As a result, martensitic transformation is also not possible. For now it can be concluded that stainless steel (without carbon) with a Cr content above 12% always has a ferrite structure. Ferritic Stainless Steel can have a Cr content of up to 30%. Machine Translated by Google Machine Translated by Google If at low carbon content, Ferrite is stable in all temperature ranges, then at higher carbon content the Austenite phase region can be found. The addition of 0.6% carbon content, for example, will modify the phase diagram so that the alloy will have an Austenite phase at high temperatures. Under these conditions, the steel can be quenched to produce Martensite. Machine Translated by Google In general, the higher the Cr content, the more resistant the iron is to corrosion. This is due to the formation of an oxide film layer on the surface. On the other hand, a lack of Cr content will cause a reduction in the number of protective oxide film layers. In this case, the carbon content in stainless steel needs to be kept low. If not, then chromium carbide will form so that chromium cannot reach the surface to form a protective film oxide. The addition of Ni is very important because Ni has an FCC structure which has a larger carbon solubility limit, thus reducing the chance of Chromium carbide formation which will reduce the Cr content and therefore the amount of protective oxide film layer on the surface remains formed. Machine Translated by Google Machine Translated by Google Examples of stainless steel alloys with the addition of Ni are Stainless Steel 18- 8. It has also been explained previously that Ni which has an FCC structure is a stabilizing element of FCC or Austenite in iron alloys. The presence of Ni will reduce the tendency of FCC iron to transform into BCC. At certain carbon content (< 0.03%C) the Austenite phase will even be stable at room temperature. Machine Translated by Google So far we have known two important types of stainless steel alloys, namely stainless steel alloys with low Ni content and stainless steel alloys with high Ni content. We also know three types of Stainless alloys based on their crystal structure, namely: Ferritic Stainless Steel, Martensitic Stainless Steel, and Austenitic Stainless Steel. In addition to the two things above, stainless alloys can also be grouped based on their strengthening mechanisms. Included in this group is PH Stainless Steel, which is a Stainless Steel alloy that is strengthened through the Precipitation Hardening mechanism which includes Solutionizing, Quenching, and Aging. Machine Translated by Google Machine Translated by Google Phase diagram Fe-C Machine Translated by Google Fe-Fe3C phase diagram eutectic eutectoid Machine Translated by Google Fe-Fe3C phase diagram - pure iron : at room temperature it is called ferrite or iron a which has a BCC crystal structure. Ferrite will change to austenite or g iron at a temperature of 912 0C (1674 0C) with an FCC crystal structure. At a temperature of 1538 0C (2800 0F) austenite will change to iron ferrite d and BCC crystal structure. - Fertilizer and cast iron is iron with a low carbon content of 6.7 wt %. At 6,7wt% there is a Fe3C content of 100%wt, so a carbon content of 6,7wt% is also said to have a 100wt% Fe3C content (cementite). - iron ÿ (ferrite) : maximum composition of C is 0.022 wt% at 727 0C (1341 (2) can be made magnetic 0F). Material properties: (1) low , at temperature softness, (3) density: 7.87 gr/cm3. - austenite (iron ÿ) : maximum carbon 2.11wt% at 11480C. FCC crystal structure. Austenite is non- magnetic. - iron ÿ (ferrite ÿ) : has the same form as ferrite a only the temperature is different, namely between 1394 0C to 1538 0C. - cementite (Fe3C) : formed when the solubility limit of carbon in iron a is exceeded at temperatures below 727 0C. Fe3C is also formed with the g phase at temperatures of 727 to 1148 0C. The mechanical properties of cementite are hard and brittle. The strength of some steels can be increased by cementite content. 33