Iron
MECHANICAL PROPERTIES OF IRON. Mechanical properties at elevated temperatures. The tensile strength of these pearlitic ductile irons decreases continuously with increasing temperature and 400 ° C is approximately 2 / 3 of the resistance at room temperature. For ferritic irons is less pronounced decline to 400 ° C and the resistance value is approximately% of room temperature. IS sigmas 0.2% for both ferritic and pearlitic irons, remained practically stable up to 350-400 º C, above this temperature fails quickly. The hot hardness is maintained even up to 400 º C, missing above this value. For temperatures up to 300 º C the allowable stress in static structures, like ambient temperature, can be based on the values of the sigma 0.2% obtained at room temperature. At temperatures higher than 300X the allowable stresses should be calculated on flow data. A small amount of molybdenum These properties significantly improves creep resistance and hot both ferritic to pearlitic irons. The improvements achieved with the addition of Mo can extend Tensile properties at low temperatures. As for the impact properties, there is a temperature below which the tensile elongation decreases. The sigma 0.2% increases continuously with decreasing temperature, but the tensile strength undergoes a transition. Above the transition temperature range the tensile strength tends to remain constant or increase, but once the transition temperature, the tensile strength decreases. Phosphorus, silicon and transition temperature increase on the 5th and reduce the resistance in the ductile Rago.
TENSILE STRENGTH is the maximum value of tensile stress that supports a material which depends on the speed of deformation
COMPRESSIVE STRENGTH is the maximum stress a material can withstand under a crushing burden. The compressive strength of a material that fails due to a burst fracture can be defined in fairly tight limits, as an independent property. However, the compressive strength of materials that do not break in compression is defined as the amount of effort required to deform the material an amount arbitrated. The compressive strength is calculated by dividing the maximum load by the original cross-sectional area of a specimen in a compression test.
Elongation is a type of deformation. Strain is simply the change in the way that experience anything live. When we talk about stress, the sample is deformed by stretch, becoming longer.
Torsional stiffness is the action and effect of bending or twisting in a helical one thing. [Mechanics] Change in the shape of a body when subjected to various forces. [Mechanics] Deformation of a body produced by submitting two sets of forces, which act in opposite directions and parallel pianos, so that each body section is rotated with respect to another section nearby.
RESISTANCE TO THE COURT that resistance is that the power of the machine tool is greater than the power required for cutting the material of the blank.
PHYSICAL PROPERTIES Coefficient of thermal expansion. The expansion characteristics of cast irons are complex due to the transformations taking place in solution, due to precipitation of graphite, graphitization of the fence and the formation of austenite above 700 ° C. Corrosion Resistance. In some applications the corrosion resistance of ductile iron is similar to gray iron and often superior to that of steel. Ductile iron pipes usually applied in sewage, may be protected by anodizing, zinc coated, plastic covers and in some cases, coated with polyurethane. Collaborated by: Peter E. Architecture and Construction in ARQHYS, strength properties and creep up to 459 º C.
Torque is characterized geometrically because any curve parallel to the axis of the piece was no longer contained the plane formed initially by the two curves. Instead a curve parallel to the shaft is twisted around it. – Fatigue of materials refers to a phenomenon by which the rupture of materials under cyclic dynamic loads (forces repeatedly applied to the material) occurs at loads below the static charges that produce the rupture. An example of this is in a wire: flexing repeatedly breaks easily, pear force to do to break into a single flex is great. – Cast iron: You eutectic cells interconnected graphite flakes. Inoculation cooperation to create smaller eutectic cells to improve endurance.
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It produces low tensile strength, this is for the large flakes of graphite. Resistance can be achieved more by reducing the carbon equivalent through the alloy or heat treatment
Its properties are, high compressive strength, resistance to thermal fatigue and damping against vibration.
CAST WHITE: white cast irons are used for their hardness and abrasion resistance. Martensite can occur during heat treatment.
Malleable iron, heat is created to try non-alloy white cast iron, from white cast iron there are two types of ductile iron, malleable cast iron is achieved by cooling the casting and thus reach the second stage of graphitization, this cast has good toughness, ductile iron perpita is created by cooling the austenite in air or oil shale or in order to form martensite.
DUCTILE CAST IRON OR: For the spheroidal graphite cast iron is required to create this metal are the following steps:
• Desulfurization: The sulfur causes the form of graphite flakes grow in the smelting furnaces in melting iron sulfur removed.
• Modulation, magnesium is applied, this removes any sulfur and oxygen remaining in the metal. Not be emptied after nodulation iron, iron becomes cast iron.
• Inoculation: An effective stabilizer is magnesium carbides and solidification causes the white iron is formed. After nodulation should be inoculated iron.
• Compact Graphite Iron. The form is intermediate between flake graphite and spheroidal. It is compact graphite gives strength and ductility and the metal retains a good thermal conductivity and absorption properties of vibration
MALLEABLE CAST IRON. This type of casting is obtained by applying to the cast iron white an annealing treatment by heating to a temperature between 850 and 950 C º in order to decompose the cementite leaving the free carbon as nodules, irregular, commonly called carbon tempering can be of 2 types:
• The first is a “European” obtained by the above treatments for 1 or 2 days and in the presence of ferric oxide which oxidizes the carbon surface, with the natural reduction in the percentage of the final composition.
• The second type is called “American malleable iron, which is obtained by extending the annealing, sometimes up to 8 days, and with a ferritic structure in the background.
NODULAR CAST IRON. This type of casting is also called ductile cast iron and spheroidal graphite cast iron. Characterized because it appears as spheroidal graphite or tiny cell. The carbon content is equal to nodular cast iron. Spheroidal graphite particles are formed during solidification, due to the presence of small amounts of some knot elements such as magnesium and serious.
IRON refers generally, but identifies a large group of ferrous metals which solidify with a. The color of a fractured surface can be used to identify an alloy. White cast iron is named after its white surface when fractured due to its carbide impurities allow cracks to pass straight through. Grey cast iron is named after its gray fractured surface, which occurs because the graphitic flakes deflect a passing crack initiate countless new cracks as the material breaks.