2.3 Cogne grade 329HT
Cogne grade 329HT (steel grade: 1.4462) is a type of duplex stainless steel. It contain higher content in molybdenum than other steel. The advantages of 1.4462 is high yield and tensile stress. It is able to endure corrosion and stress corrosion cracking. The cost is also higher than other as grade1.4436 and 1.4301.
Due to its outstanding properties, it is always used in many construction and industrial aspects that location in seawater. For example, the offshore drilling in petroleum engineering.
figure(2.3.1) Chemical composition og 329HT figure(2.3.2) Mechanical and physical properties of 329HT duplex stainless seel
2.4 Microstructure and the phases in duplex stainless steel
(a) General microstructure in Duplex stainless steel
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Then, the materials cool down slowly. Through this process, the dislocations of the structure reduce. The strength of materials drop and raise the toughness flexibility and ductility. Also, the nucleation and growth will occurs in annealing.
(b) Quenching
Quenching is a heat treatment method in steel that heat the material in a high temperature and then cool down in a short time. The material will become much softer and readily for further treatment. Quenching process usually is divided in two ways: water quench and oil quench.
(c) Tempering
After quenching, the heated steel will cool down. Due to the different rate of cooling, the different types of microstructure will be formed. The formation of pearlite, bainite and martensite determine the physical properties such as hardness, strength and ductility.
(d) Precipitation
purpose we use this for is to drill wells into so that we may obtain the water that
Have you ever wondered why the plastic bag that you left on the porch during winter cracks or breaks more easily than when you left it during summer time but a piece of wood which was left just like the plastic bag has no effect whatsoever? This is because of a phenomenon, which only happens to polymers, known as the glass transition. For each polymer, there is a certain temperature at which the amorphous polymers undergo a second order phase transition from a rubbery and viscous amorphous solid to a brittle and glassy amorphous solid called the glass transition temperature, Tg.1 When the polymer, or in this case, the plastic bag, is cooled below their glass transition temperature, it becomes hard and brittle like a glass but when it is used above their glass transition temperatures, it might have a different effect than when used at room temperature or below the glass transition temperature as normally, different types of polymers like clothes, food packaging, insulations for wires, etc. are either used above their glass transition temperatures or
The machinability of copper and copper alloys is improved by lead, sulfur, tellurium, and zinc while it deteriorates when tin and iron are added. Lead in brass alloys with concentrations around 2 wt%, improves machinability by acting as a microscopic chip breaker, and tool lubricant, while they increase the brittleness of the alloy [17]. Lead additions are used to improve machinability. The lead is insoluble in the solid brass and segregates as small globules that help the swarf to break up in to small pieces and may also help to lubricate the cutting tool action. The addition of lead is however, affect cold ductility which may control both the way in which material is produced and the extent to which it can be post-formed after machining
...). Effect of Cold Drawing on Microstructure and Corrosion Performance of HighStrength. Mechanics of TimeDependent , 307-319.
When most materials are heated they expand and this increase their volume. One example of expansion is the fitting of the starter ring gear to the flywheel. The gear is heated until it expands sufficiently to pass over the rim of the flywheel, and when it is cool the gear tries to return to its original size, this gripping the flywheel with considerable force.
Defluidization occurs when the particles in the bed adhere. When two particles touch, material at the point of contact migrates forming a neck that is strong enough to withstand the disruptive forces in the fluidized bed. Two categories of adhesion can be discerned. The first type is visco-plastic sintering and it occurs with glassy materials. With these materials, migration is limited by the ability of the material to flow. With increasing temperature the viscosity of the material is reduced and hence the material flows and the size of the neck is increased. At some point, the necks are sufficiently large and strong enough to cause defluidization. The second type occurs when a large quantity of liquid is formed by melting or by chemical reaction. With an increase in temperature, a phase boundary may be crossed bring about rapid defluidization. The liquid formed has a relatively low viscosity and defluidization is caused by the amount of liquid present. This section will primarily focus on visco-plastic sintering.
Strain hardening is the additional stress required to cause slip in a material. It occurs when dislocations in a crystal interact with each other or when the dislocations observe hindrance in their motion. Either dislocations pile up at the barriers of slip plane of crystal or they intersect other dislocations. The latter can result in jogs which restrict its motion. Jogs readily occur in the cases of screw dislocations which cases to restrict the dislocation movement thus increasing strain hardening but not so in case pf edge dislocation. The strain hardening or work hardening behavior for FCC, BCC and HCP can be observed by taking the case of Iron, copper and magnesium where iron is BCC, copper is
Stainless steel is a type of alloy that has a very strong lattice structure (an arrangement/ shape of the crystals or other objects) which in some case can be more beneficial than others depending on the type of application it may be used for. In many cases this structure will make the material more suited to being used in engineering applications such as tools for instance a hammer (stainless steel alloys) , also they can be used for gears, engines, electrical motors and hydraulic systems because the structure makes the material so strong. So when the arrangement of the structure is as above it makes the overall material even stronger which makes it a good for all the applications stated above. I believe its strength and durability are its main properties as these are commonly needed in the engineering industry, although it is also very well known to be used for its corrosion resistance as it is resistant to many types of corrosion. It is used for these properties because the components such as gears need to be strong in order to keep transferring and altering the rotary motion and torque exhibited in the machine that it may be used in, durable to withstand any loads or pressure put onto it and also corrosion resistance to give the components a bigger life span and increase its rate of work throughout its required use.
This cement would be used in the water proofing of “floors, cisterns, and aqueducts” (Rabun). This cement was used all though out ancient Rome. It was used primarily in the constructing of the aqueducts the Romans are known for today. While this cement that crafted and produced primary for the use of building aqueducts, the romans also used it for waterproofing building that were nearby pipes or channels of water. During the time, water sources weren’t just abundant, engineers were hired to venture and locate any flowing springs.
Precipitation hardening is a process that using very high temperature to strengthen an object such as , metal alloy and aluminium , precipitation hardening process also referred to age hardening . There are three main process that involve in Precipitation Hardening , the first process is Solution Treatment , second process is Quenching , and thirdly is Aging . On the other hand , Dispersion strengthening only have two process which is aluminium alloys made by powder metallurgy are used in the nuclear power field for sheathing fuel rods , and also used for heat exchanger tubing and high temperature turbine blades . It is presently receiving significant attention in the design of a variety of advanced power generation and aerospace devices , such as interactive components in magnetic confinement fusion reactor , rotating –source neutron targets , rocket nozzles , combustion chamber liners and combustor walls and leading edges . These applications require materials with a high thermal conductivity in combination with a high elevated temperature strength in oxygen or hydrogen .
The basis for the understanding of the heat treatment of steels is the Fe-C phase diagram. Because it is well explained in earlier volumes of Metals Handbook and in many elementary textbooks, the stable iron-graphite diagram and the metastable Fe-Fe3 C diagram. The stable condition usually takes a very long time to develop, especially in the low-temperature and low-carbon range, and therefore the metastable diagram is of more interest. The Fe-C diagram shows which phases are to be expected at equilibrium for different combinations of carbon concentration and temperature. We distinguish at the low-carbon and ferrite, which can at most dissolve 0.028 wt% C at 727 oC and austenite which can dissolve 2.11 wt% C at 1148 oC. At the carbon-rich side we find cementite. Of less interest, except for highly alloyed steels, is the d-ferrite existing at the highest temperatures. Between the single-phase fields are found regions with mixtures of two phases, such as ferrite + cementite, austenite + cementite, and ferrite + austenite. At the highest temperatures, the liquid phase field can be found and below this are the two phase fields liquid + austenite, liquid + cementite, and liquid + d-ferrite. In heat treating of steels the liquid phase is always avoided. Some important boundaries at single-phase fields have been given special names. These include: the carbon content at which the minimum austenite temperature is attained is called the eutectoid carbon content. The ferrite-cementite phase mixture of this composition formed during cooling has a characteristic appearance and is called pearlite and can be treated as a microstructural entity or microconstituent. It is an aggregate of alternating ferrite and cementite particles dispersed with a ferrite matrix after extended holding close to A1. The Fe-C diagram is of experimental origin. The knowledge of the thermodynamic principles and modern thermodynamic data now permits very accurate calculations of this diagram.
The purpose of making alloys is to alter or enhance a metal’s chemical and physical properties in order to use the alloy for a specific function. For example, alloys can be made to enhance the hardness, magnetism, tensile strength and corrosion resistance of a metal. The harder alloy can replace the use of another metal that does not have the required and ideal characteristics for a particular function.
"Using GMAW-P with Aluminum and Stainless Steel." - TheFabricator.com. Kodi Welch, 05 Nov. 2013. Web. 28 Apr. 2014.
However, most metals in their natural states are less than the desired choice for the jobs they are required to do. For example, iron, although it is an incredibly strong metal in its natural form, it is delicate and rusts quite quickly in damp air. So to enhance the properties of the metal they are combined with other substances to create an alloy, which are often used instead of pure metals to generate a more durable product.
Toughness is the ability of a metal to mutilate plastically and to absorb energy in the process before it breaks or fracture. Metals can be heat treated to alter the properties of strength, ductility, toughness, hardness or resistance to corrosion. This can be done by using heat treatment processes which include precipitation strengthening, quenching, annealing and tempering. Annealing and tempering are the most prominent methods for treating metals. A material may become more or less brittle, harder or softer, or stronger or weaker, depending on the treatment used.