Knowledge of popular science of metallic heat treatment

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6% above, the specification already used cementite technology. But serve as an individual at that time " craft " secret, outside agreeing, pass, progress is very consequently slow. 1863, the metallographic that British metallography differs 6 kinds when the home revealed iron and steel to fall in microscope with rocksy is organized, when card understands steel to heating and cool, in-house meeting produces constituent change, the photograph when the high temperature in steel is in urgent cold when change is a kind of harder look. French the compose of the different that be the same as element of the iron of establish of Ao Simeng heart is academic, and the iron carbon phasor that English Austin makes the earliest, for craft of modern heat treatment preliminary laid theoretical foundation. Meanwhile, people still considered to be in of metallic heat treatment heat the to the metal protection method in the process, with avoiding to heat the oxidation of the metal in the process is mixed decarbonization. 1850 ～ 1880, to using all sorts of gas (such as hydric, gas, carbon monoxide) undertake protective heating to ever had a series of patent. English Lai gram obtained 1889 ～ 1890 the patent of a variety of metallic brightness heat treatment. Since 20 centuries, the transplanting of the development of metallic physics and other new technology applies, make craft of metallic heat treatment gets greater progress. A striking progress is 1901 ～ 1925, in industrial production applied bowl furnace undertakes aeriform cementite; Voltage of 30 time occurrence dew point plan, make the carbolic situation of the atmosphere inside furnace is achieved can accuse, excogitate the method that with carbon dioxide first class of explore of infra-red appearance, oxygen commands force of carbon of the atmosphere inside furnace further again later; 60 time, heat treatment technology handled the function of plasma field, developed technology of ionic nitriding, cementite; The application of technology of laser, electron beam, make the metal obtained new exterior heat treatment and thermo-chemical treatment means again. The craft of craft heat treatment of metallic heat treatment includes to heat commonly, heat preservation, cooling 3 processes, heat only sometimes and cool two processes. These processes join each other, cannot discontinuous. Burner of vacuum temper by dipping in water heats is one of important working procedure of heat treatment. Of metallic heat treatment heat the method is very much, the earliest it is to use charcoal and coal to serve as heat source, use liquid and aeriform fuel then. Electric application makes heat to be controlled easily, and pollute without the environment. Use these heat source to be able to heat directly, also can carry the salt of melt or metal, particle of down to float undertakes heating secondhand. When the metal heats, workpiece is exposed in air, often produce oxidation, decarbonization (namely content of carbon of surface of steely spare parts reduces) , this has very adverse effect to the exterior function of the spare parts after heat treatment. Consequently the metal should be in normally can accuse atmosphere or salt of medium, melt counteracts protective atmosphere heat in vacuum, also can use coating or pack a method to undertake protective heating. Heat one of vital technology parameter that temperature is heat treatment craft, choice and control heat temperature, it is the main problem that assures heat treatment quality. Heat the goal that temperature follows the metallic material that is handled and heat treatment is different and different, but it is to heat to change commonly temperature above, in order to acquire high temperature organization. Additionally change needs proper time, because this becomes what metallic workpiece surface achieves a requirement,heat when temperature, still must hold proper time in this temperature, make temperature of inside and outside consistent, make microstructure change complete, this paragraph of time calls heat preservation time. Use high-energy density heats and when exterior heat treatment, heat speed is splitting, do not have heat preservation time commonly, and the heat preservation time of thermo-chemical treatment often longer. Refrigeration also is the indispensable measure in heat treatment process, because technology is different and cooling method is different, basically be control cooling rate. The cooling rate of general anneal is the slowest, the cooling rate of normalizing is rapidder, quenched cooling rate is rapidder. But because steel is planted,still have diverse demand, for example empty hard steel can use the cooling rate like normalizing to have temper by dipping in water hard. Craft cardinal principle can divide metallic heat treatment to be mixed for integral heat treatment, surface heat treatment thermo-chemical treatment 3 kinds big. The basis heats medium, heat of temperature and cooling method different, each kinds big can distinguish again the heat treatment craft that is a certain number of differring. Same kind the metal uses different heat treatment technology, can acquire different organization, have different property thereby. Iron and steel is the metal with the widest application on industry, and steely microstructure is most complex also, because this is steely sort of heat treatment craft is various. Heat treatment of whole of poor Wen Cuihuo is to workpiece whole heats, cool with appropriate rate next, with changing its full physical power learns the craft of metallic heat treatment of function. Steely whole heat treatment has anneal, normalizing roughly, quench and temper 4 kinds of basic technology. Anneal is heat workpiece proper temperature, use different heat preservation time according to material and work measure, undertake slow refrigeration next, the purpose is to make interior organizes the metal to achieve or approach balance state, gain good technical properties and performance characteristics, perhaps organize preparation to quench further. Normalizing is heat workpiece cool in air after appropriate temperature, the effect of normalizing is the same as anneal likeness, the organization that just gets is finer, commonly used the cutting function at improving data, also use at not tall to a few requirements spare parts to serve as final heat treatment sometimes. Quenching is heat workpiece after heat preservation, temper by dipping in water waits in water, oil or other and inorganic salt, organic aqueous solution cool quickly in cold medium. The steel after quenching harden, but become fragile at the same time. To reduce steel brittleness, the steel after will quenching proper temperature undertakes the in prep above room temperature some under 650 ℃ long heat preservation, undertake cooling again, this kind of craft calls temper. Anneal, normalizing, quench, temper is integral heat treatment is medium " 4 fire " , among them quench as close as temper relation, often cooperate to use, be short of one cannot. "4 fire " as heat of temperature and cooling means different, evolve into a different heat treatment technology again. To obtain particular strength and tenacity, the craft that quenchs with high temperature temper union rises, call tone to pledge. Certain alloy quenchs after fashioning supersaturation solid solution, will keep longer below its park room temperature or tallish proper temperature, wait in order to raise the hardness of alloy, intensity or electric sex magnetism. Such heat treatment craft calls ageing treatment. Rise union of forming deformation and heat treatment are effective and close together ground undertake, the method that makes workpiece obtains very good intensity, tenacity to cooperate calls deformation heat treatment; Vacuum heat treatment is called in the heat treatment that lose atmosphere of calm sb's anger or has in vacuum, it can make workpiece does not oxidize not only, not decarbonization, surface of the workpiece after maintaining processing is bright and clean, improve the performance of workpiece, still can connect ooze agent to have thermo-chemical treatment. The induction heats quench exterior heat treatment is to heat only workpiece surface layer, in order to change its surface layer the craft of metallic heat treatment of mechanical function. To heat only workpiece surface layer and do not make overmuch quantity of heat passes into workpiece interior, use heat source must have high energy density, give bigger heat energy on the workpiece of unit area namely, make workpiece surface layer or local can short when or instantaneous reachs high temperature. The main method of exterior heat treatment has blaze to quench heat with the induction heat treatment, commonly used heat source has the blaze such as oxygen acetylene or oxygen propane, faradic, laser and electron beam to wait. Thermo-chemical treatment is the craft of metallic heat treatment that expresses a chemical composition, organization and function through changing workpiece. The point with thermo-chemical treatment and exterior different heat treatment is the chemical class status that latter changed workpiece surface layer. Thermo-chemical treatment is put work in the medium that contains carbon, nitrogen or other alloying element (gas, liquid, solid) in heat, heat preservation is longer, make thereby the element such as carbon of infiltration of workpiece surface layer, nitrogen, boron and chromium. After infiltration element, if quench,have technology of other heat treatment even sometimes reach temper. The main method of thermo-chemical treatment has metal of cementite, nitriding, ooze. Heat treatment is mechanical spare parts and one of important working procedure in be versed in the mould makes a process. For cardinal principle, it can assure and improve all sorts of performance of workpiece, be like wear-resisting, anti-corrosive etc. Return the organization that can improve semifinished product and stress condition, with benefit at having all sorts of cold, hot work. For example course of Bai Kouzhu iron is long anneal processing can obtain malleable iron, raise plasticity; Gear uses right heat treatment technology, service life can be compared not the gear twice of classics heat treatment or a few times land increases; Additional, the carbolic steel of valence cheap passes infiltration the alloy steel property that certain alloying element has certain price to hold high, can replace certain refractory steel, stainless steel; Industry pattern needs to just can be used through heat treatment entirely almost. CNC Milling CNC Machining