Colt Peacemaker, showing case-hardening colors on the frame Case-hardening or surface hardening is the process of hardening the surface of a metal object while allowing the metal deeper underneath to remain soft, thus forming a thin layer of harder metal (called the "case") at the surface. For iron or steel with low carbon content, which has poor to no hardenability of its own, the case-hardening process involves infusing additional carbon or nitrogen into the surface layer. Case-hardening is usually done after the part has been formed into its final shape, but can also be done to increase the hardening element content of bars to be used in a pattern welding or similar process. The term face hardening is also used to describe this technique, when discussing modern armour.
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Typical applications for case hardening are gear teeth, cams, shafts, bearings, fasteners, pins, hydraulic piston rods, automotive clutch plates, tools, dies and tillage tools.
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The present study investigated the use of a laser-beam, in order to carburize the surface of DIN 15CrNi6 low-alloy, case-hardening steel.
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Bruthans, J., Filippi, M., Slavík, M. and Svobodová, E., 2018. Origin of honeycombs: Testing the hydraulic and case hardening hypotheses. Geomorphology, 303, pp.68-83.Paradise, T.R., 2013.
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Case hardening processes harden only the exterior of the steel part, creating a hard, wear resistant skin (the "case") but preserving a tough and ductile interior. Carbon steels are not very hardenable meaning they can not be hardened throughout thick sections. Alloy steels have a better hardenability, so they can be through- hardened and do not require case hardening. This property of carbon steel can be beneficial, because it gives the surface good wear characteristics but leaves the core flexible and shock-absorbing.
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The thick layer will trap moisture inside the mango making it really difficult to entirely dehydrate the mango. This phenomenon of developing hard skin-like outer layer is called case-hardening. Case hardening is the result of a large amount of heat dehydrated production, which hardens the exterior of the fruit or vegetable, making it difficult to avoid moisture crumb. The food dried at a very high temperature, the outer surface will harden, preventing moisture from escaping through the center of the slice.
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Certain pre-industrial case hardening processes include not only carbon-rich materials such as charcoal, but nitrogen-rich materials such as urea, which implies that traditional surface hardening techniques were a form of carbonitriding.
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The reached materials dissolved in the surface infiltrates in the weathered surface and cement the silica-aluminous remnant materials. The surface induration by means of this process is named case hardening.Dorn, R.L. 2004. Case hardening.
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Earth Surface Process and Landforms, 24, 271-278 A similar phenomenon is observed in felsic alkaline rocks, such as nepheline syenite, alkaline syenite, phonolite, and trachyte, because of weathering vulnerability of nepheline and alkaline feldspar.Motoki, A., Soares, R., Lobato, M., Sichel, S.E., Aires, J.R. 2007. Feições intempéricas em rochas alcalinas félsicas de Nova Iguaçu, RJ. Revista Escola de Minas, 60-3, 451-548 The case hardening on trachytic clasts of volcanic breccia shows peculiar fabrics. The Mars scientific exploring machine Spirit has observed case hardening present of the rock surface present at Gusev meteorite Crater.
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Applies various chemical processes (browning, bluing, Parkerization, among others) to the metal parts of guns to develop corrosion resistant surface layers on the steel. They may also apply case hardening to low carbon steel parts. Case hardening is a combined chemical and heat-treatment process which introduces carbon into the surfaces of low steel alloys that does not contain sufficient carbon to allow total ("through") heat treatment. This carbon rich surface is then heat treated resulting in a thin, very hard surface layer with a tough, malleable core.
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This leads to reversed stresses; compression stresses on the shell and tension stresses in the core. This results in unrelieved stress called case hardening. Case-hardened [wood] may warp considerably and dangerously when the stress is released by sawing.
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Many modern replicas of older firearms, particularly single action revolvers, are still made with case-hardened frames, or with case coloring, which simulates the mottled pattern left by traditional charcoal and bone case-hardening. Another common application of case-hardening is on screws, particularly self-drilling screws. In order for the screws to be able to drill, cut and tap into other materials like steel, the drill point and the forming threads must be harder than the material(s) that it is drilling into. However, if the whole screw is uniformly hard, it will become very brittle and it will break easily.
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Colour case hardening occurs when soft steels were packed in a reasonably airtight crucible in a mixture of charred leather, bone charcoal and wood charcoal. This crucible was heated to for up to 6 hours (the longer the heat was applied the thicker the case hardening). At the end of this heating process the crucible is removed from the oven and positioned over a bath of water with air forced through a perforated coil in the bottom of the bath. The bottom of the crucible is opened allowing the contents to drop into the rapidly bubbling water.
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Although inexpensive, barium chloride finds limited applications in the laboratory and industry. In industry, barium chloride is mainly used in the purification of brine solution in caustic chlorine plants and also in the manufacture of heat treatment salts, case hardening of steel. Its toxicity limits its applicability.
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Both carbon and alloy steels are suitable for case-hardening; typically mild steels are used, with low carbon content, usually less than 0.3% (see plain-carbon steel for more information). These mild steels are not normally hardenable due to the low quantity of carbon, so the surface of the steel is chemically altered to increase the hardenability. Case-hardened steel is formed by diffusing carbon (carburization), nitrogen (nitriding) and/or boron (boriding) into the outer layer of the steel at high temperature, and then heat treating the surface layer to the desired hardness. The term case- hardening is derived from the practicalities of the carburization process itself, which is essentially the same as the ancient process.
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This function is typically repeated, varying the duration of gas input and diffusion time. Once the workload is properly "cased", the metal is quenched using oil or high pressure gas (HPGQ). For HPGQ, nitrogen or, for faster quench helium, is commonly used. This process is also known as case hardening.
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The steel work piece is placed inside a case packed tight with a carbon-based case-hardening compound. This is collectively known as a carburizing pack. The pack is put inside a hot furnace for a variable length of time. Time and temperature determines how deep into the surface the hardening extends.
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Heat treatment techniques include annealing, case hardening, precipitation strengthening, tempering, and quenching. Although the term "heat treatment" applies only to processes where the heating and cooling are done for the specific purpose of altering properties intentionally, heating and cooling often occur incidentally during other manufacturing processes such as hot forming or welding.
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This is the predecessor of all metal colouring typically employed in the firearms industry. Contemporary heat-treatable steels did not exist or were in their infancy. Soft, low-carbon steel was used, but strong materials were needed for the receivers of firearms. Initially case hardening was used but did not offer any aesthetics.
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Wood is air-dried or dried in a purpose built oven (kiln). Usually the wood is sawn before drying, but sometimes the log is dried whole. Case hardening describes lumber or timber that has been dried too rapidly. Wood initially dries from the shell (surface), shrinking the shell and putting the core under compression.
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Carbon is used in chemical reduction at high temperatures. Coke is used to reduce iron ore into iron (smelting). Case hardening of steel is achieved by heating finished steel components in carbon powder. Carbides of silicon, tungsten, boron and titanium, are among the hardest known materials, and are used as abrasives in cutting and grinding tools.
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This phenomenon is attributed to the weathering by means of surface water, being considered to be an evidence of liquid water in a far past on that planet.Farmer, J.D. 2005. Case-hardening of rocks on Mars: evidence for water- mediated weathering processes. Abstracts of annual meeting of the Geological Society of America, Salt Lake City, paper 223-5, CD.
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Principal products included alloy and carbon steel bars (case hardening, bright drawing, free cutting, machining, hot and cold forging), special sections, railway bearing plates, rounds, squares, flats, angles, channels, joists, billets, blooms, slabs and large forging ingots. Round Oak manufactured a weldable extra high-strength steel under the brand name, 'Thirty-Oak'.The Acorn. House magazine of Round Oak Steelworks.
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This process can be done solely for the mechanical properties (hardness and toughness) it imparts, or, by packing the parts in bone charcoal and other chemicals and heating in a heat treatment furnace for varying time periods, it is possible to introduce rich colors into the carbonized surface. This type of case hardening, known as color case hardening, is prized for its rich mottled blues, purples, browns and grey tones. It is possible, with highly skilled craftsmen using highly proprietary processes, to control the hues and patterns so closely that one familiar with high grade custom firearms can usually recognize the maker of another shooter's firearm solely by the colors and patterns on its parts; an important distinction on extremely costly firearms of the highest grade. Typically, its use is usually restricted to receivers, rarely barrels.
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Boron can form intermetallic compounds and alloys with such metals of the composition MnB, if n > 2.Van der Put 1998, p. 123 Ferroboron (15% boron) is used to introduce boron into steel; nickel-boron alloys are ingredients in welding alloys and case hardening compositions for the engineering industry. Alloys of silicon with iron and with aluminium are widely used by the steel and automotive industries, respectively.
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Although providing corrosion resistance, the colored surface layers are subject to wear and may also fade with time. Antique firearms for sale frequently note the specific percentage of the factory original case coloring remaining on the receiver and lockplates. Renewing this color case hardening to the specific patterns of the firearm when it was new has become an important sub-area of the gunsmithing field.
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False indications are those caused by factors not related to the principles of the testing method or by improper implementation of the method, like film damage in radiography, electrical interference in ultrasonic testing etc. True indications are further classified as relevant and non relevant. Relevant indications are those caused by flaws. Non relevant indications are those caused by known features of the tested object, like gaps, threads, case hardening etc.
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Imperial Roman granite was quarried mainly in Egypt, and also in Turkey, and on the islands of Elba and Giglio. Granite became "an integral part of the Roman language of monumental architecture". The quarrying ceased around the third century AD. Beginning in Late Antiquity the granite was reused, which since at least the early 16th century became known as spolia. Through the process of case-hardening, granite becomes harder with age.
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On the rock surface in the case hardening of alkaline felsic rocks, the weathering selectively affects certain minerals. Nepheline is very sensitive to weathering and is altered to natrolita and cancrinite. On the outcropping surface of a nepheline syenite, phonolite or nepheline syenite gneiss, the minerals formed by nepheline alteration appear white in colour on the dark- coloured weathered background. After the nepheline alteration products are leached, small holes are formed on the rock.
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Collapse is a defect that results from the physical flattening of fibres to above the fibre saturation point and is thus not a form of shrinkage anisotropy. The standard organizations in Australia and New Zealand (AS/NZS 4787, 2001) have developed a standard for timber quality. The five measures of drying quality include: # moisture content gradient and presence of residual drying stress (case-hardening); # surface, internal and end checks; # collapse; # distortions; # discolouration caused by drying.
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Carbon itself is solid at case-hardening temperatures and so is immobile. Transport to the surface of the steel was as gaseous carbon monoxide, generated by the breakdown of the carburising compound and the oxygen packed into the sealed box. This takes place with pure carbon but too slowly to be workable. Although oxygen is required for this process it is re-circulated through the CO cycle and so can be carried out inside a sealed box.
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This is overcome by ensuring that only the surface is hardened, and the core remains relatively softer and thus less brittle. For screws and fasteners, case-hardening is achieved by a simple heat treatment consisting of heating and then quenching. For theft prevention, lock shackles and chains are often case-hardened to resist cutting, whilst remaining less brittle inside to resist impact. As case-hardened components are difficult to machine, they are generally shaped before hardening.
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Rolling produces pancetta's distinctive shape, while the casing prevent case hardening in the latter stages of the production process. Following rolling and packing, the pork undergoes enzymatic reactions facilitated by exposure to a warm environment of 22–24 °C for 24 to 36 hours. It is simultaneously exposed to cold smokes for desirable colours and flavours and to prevent moulding. Finally, the smoked pork is held at 12–14 °C and 72–75% relative humidity for 3–4 weeks for drying.
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This lowers the stacking fault energy, leading to repulsion of the partial dislocations, which thus makes the material stronger. Surface carburizing, or case hardening, is one example of solid solution strengthening in which the density of solute carbon atoms is increased close to the surface of the steel, resulting in a gradient of carbon atoms throughout the material. This provides superior mechanical properties to the surface of the steel without having to use a higher-cost material for the component.
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In a traditional charcoal or coal forge, the fuel is really just carbon. In a properly regulated charcoal/coal fire, the air in and immediately around the fire should be a reducing atmosphere. In this case, and at elevated temperatures, there is a tendency for vaporized carbon to soak into steel and iron, counteracting or negating the decarburizing tendency. This is similar to the process by which a case of steel is developed on a piece of iron in preparation for case hardening.
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The company used to maintain an "Old Armory Custom Shop" which produced custom firearms to order. These firearms featured expensive traditional materials and techniques such as engraving or hand engraving, gold inlay, damascening, case hardening, polishing, and fine metal plating, or other finish. USFA was the only firearm company still manufacturing in the city of Hartford, Connecticut, when it closed in 2011. Due to space limitations, the company built an additional production location outside of the Blue Dome in order to accommodate their CNC machinery.
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Electroplating of acid gold on underlying copper- or nickel-plated circuits reduces contact resistance as well as surface hardness. Copper-plated areas of mild steel act as a mask if case hardening of such areas are not desired. Tin-plated steel is chromium- plated to prevent dulling of the surface due to oxidation of tin. Electroplating, or electroless plating may be used as a way to render a metal part radioactive, by using an aqueous solution prepared from nickel–phosphorus concentrates which contain radioactive hypophosphite 32P ions.
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Carburization of steel involves a heat treatment of the metallic surface using a source of carbon. Carburization can be used to increase the surface hardness of low carbon steel. Early carburization used a direct application of charcoal packed around the sample to be treated (initially referred to as case hardening), but modern techniques use carbon-bearing gases or plasmas (such as carbon dioxide or methane). The process depends primarily upon ambient gas composition and furnace temperature, which must be carefully controlled, as the heat may also impact the microstructure of the remainder of the material.
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Hardening is desirable for metal components that are subject to sliding contact with hard or abrasive materials, as the hardened metal is more resistant to surface wear. However, because hardened metal is usually more brittle than softer metal, through-hardening (that is, hardening the metal uniformly throughout the piece) is not always a suitable choice. In such circumstances, case-hardening can produce a component that will not fracture (because of the soft core that can absorb stresses without cracking), but also provides adequate wear resistance on the hardened surface.
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The sealing is necessary to stop the CO either leaking out or being oxidised to CO2 by excess outside air. Adding an easily decomposed carbonate "energiser" such as barium carbonate breaks down to BaO + CO2 and this encourages the reaction :C (from the donor) + CO2 <—> 2 CO increasing the overall abundance of CO and the activity of the carburising compound. It is a common knowledge fallacy that case-hardening was done with bone but this is misleading. Although bone was used, the main carbon donor was hoof and horn.
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In the early 19th century the manufacturing process shifted towards using stamped strips in place of individual steel studs. The idea behind the design was that the polished steel faces would catch the light and sparkle in a similar way to the then highly fashionable diamonds. The studs were made by forming them from steel and giving them a partial polish before case-hardening and giving them a final polish. Aside from the studs some items of cut steel jewellery used highly polished steel chains in their design.
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Drying defects are the most common form of degrade in timber, next to natural problems such as knots (Desch and Dinwoodie, 1996). There are two types of drying defects, although some defects involve both causes: # Defects from shrinkage anisotropy, resulting in warping: cupping, bowing, twisting, crooking, spring and diamonding. # Defects from uneven drying, resulting in the rupture of the wood tissue, such as checks (surface, end and internal), end splits, honey-combing and case hardening. Collapse, often shown as corrugation, or so-called washboarding of the wood surface, may also occur (Innes, 1996).
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The plates in the lorica segmentata armour were made by overlapping ferrous plates that were than riveted to straps made from leather.It is unknown what animal was used to make the leather and if the leather was tanned or tawed. The plates were soft iron on the inside and rolled mild steel on the outside, making the plates hardened against damage without becoming brittle.David Sim (at Reading University) This case hardening was done deliberately by packing organic matter tightly around them and heating them in a forge, transferring carbon from the burnt materials into the surface of the metal.
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Type-founding as practiced in Europe and the West consists of three stages: ; Punchcutting: If the glyph design includes enclosed spaces (counters) then a counterpunch is made. The counter shapes are transferred in relief (cameo) onto the end of a rectangular bar of mild steel using a specialized engraving tool called a graver. The finished counterpunch is hardened by heating and quenching (tempering), or exposure to a cyanide solution (case hardening). The counterpunch is then struck against the end of a similar rectangular steel bar—the letterpunch—to impress the counter shapes as recessed spaces (intaglio).
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The Walton Sub-Group (eQa) of pumiceous fine- grained sand and silt with interbedded peat, pumiceous gravelly sand, diatomaceous mud, and non-welded ignimbrite and tephra formed low hills, up to 50 m above the Hamilton Basin plain, on and around which younger sediments have been deposited. In this area they are named the Puketoka Formation. It is highly pumiceous, and, due to silica case-hardening, is able to form vertical bluffs, now weathered, eroded, dissected and largely buried by younger sediments. Taupo Formation (Q1a) was laid down in the trench cut through the Hinuera surface.
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As a modern civilian offspring of the Karabiner 98k service rifle, the new Mauser M 98 series offers several features and factory options, that are also typical for sporterised Mauser Karabiner 98k ex-service rifles, ranging from various technical departures from the basic Mauser service rifle it was based on to luxury wood grades, gold inlays, engravings and surface treatments like plasma-based nitriding to protect metal parts against corrosion in aggressive environmental conditions or color case hardening. Some of the available options were originally developed and introduced by John Rigby & Co. on Rigby Mauser hunting rifles.
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Case-hardening involves packing the low-carbon iron within a substance high in carbon, then heating this pack to encourage carbon migration into the surface of the iron. This forms a thin surface layer of higher carbon steel, with the carbon content gradually decreasing deeper from the surface. The resulting product combines much of the toughness of a low-carbon steel core, with the hardness and wear resistance of the outer high-carbon steel. The traditional method of applying the carbon to the surface of the iron involved packing the iron in a mixture of ground bone and charcoal or a combination of leather, hooves, salt and urine, all inside a well-sealed box.
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Many explanations have been proposed for honeycomb and other cavernous weathering. These explanations include marine abrasion; wind corrosion; mechanical weathering resulting from short-term temperature variations; chemical weathering of the interior of the rock (core-softening) under a protective crust (case-hardening) followed by mechanical removal of the softened material; biogeochemical weathering by lichens; temperature variations acting on salt efflorescence in coastal regions; and salt weathering. Most commonly, researchers have advocated salt weathering as the primary explanation for the formation of honeycomb weathering. Currently, it is considered to be polygenetic in origin; being the result of complex interaction of physical and chemical weathering processes, which include salt weathering and cyclic wetting and drying.
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As the lump grows it pushes against the adjacent material and begins forcing them apart, concentrating a majority of the friction heat- energy into a very small area. This in turn causes more adhesion and material build-up. The localized heat increases the plasticity of the galled surface, deforming the metal, until the lump breaks through the surface and begins plowing up large amounts of material from the galled surface. Methods of preventing galling include the use of lubricants like grease and oil, low- friction coatings and thin-film deposits like molybdenum disulfide or titanium nitride, and increasing the surface hardness of the metals using processes such as case hardening and induction hardening.
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As well as producing their own products and supplying stationary engines for driving agricultural machinery, Advance were agents for Kerry Cars and dealers for Brown and Barlow carburettors. Advance were also pioneers and innovators, with a number of patents for components such as the 'Advance Adjustable Pulley' (the basis of the Gradua multi-speed mechanism) that aided the ascent of steep hills, and their adjustable belt fastener. They had a sister company that was incorporated in 1916, Standard Valves Ltd, which manufactured replacement valves for the motor trade. By 1936 Advance had become contractors to the War Office, Admiralty and the Air Ministry, providing specialist engineering services including cylinder re-grinding and repairs, case hardening and grinding.
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By heating thin iron rods in a carbon-rich forge, carbon could be added to the surface, making a thin layer of steel on the surface through a process called carburization (see also case hardening). From the beginning of the Iron Age, around 1200 BC, piled steel was the only way to get good steel. Obtaining the right level of carbon was an art, and was very important to the finished product. Too much carbon, or too many of the wrong trace elements, and the resulting steel becomes too hard and brittle, which can result in a catastrophic failure of a sword; too little carbon and the sword will not hold an edge.
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The Mauser M 98 was a civilian version adapted for hunting and other sporting purposes of the Gewehr 98 service rifle. Vaguely similar to the latter rifle in appearance, the M 98 was offered in many different hunting chamberings, not like the original service rifle. The Mauser M 98 series offered several features and factory options, that are also typical for sporterised ex-service rifles, ranging from various technical departures from the basic Mauser service rifle it was based on to luxury wood grades, (gold) inlays, engravings and surface treatments like color case hardening. Some of the available options were originally developed and introduced by John Rigby & Co. on Rigby Mauser hunting rifles.
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Cyaniding is a case-hardening process that is fast and efficient; it is mainly used on low-carbon steels. The part is heated to 871–954 °C (1600–1750 °F) in a bath of sodium cyanide and then is quenched and rinsed, in water or oil, to remove any residual cyanide. : 2NaCN + O2 → 2NaCNO : 2NaCNO + O2 → Na2CO3 \+ CO + N2 : 2CO → CO2 \+ C This process produces a thin, hard shell (between 0.25 and 0.75 mm, 0.01 and 0.03 inches) that is harder than the one produced by carburizing, and can be completed in 20 to 30 minutes compared to several hours so the parts have less opportunity to become distorted. It is typically used on small parts such as bolts, nuts, screws and small gears.
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This increases the chance of contamination from any contacting surface, and so must be melted in vacuum induction-heating and special, water-cooled, copper crucibles.Metals Handbook: Properties and selection By ASM International – ASM International 1978 Page 407 However, some metals and solutes, such as iron and carbon, have very high melting-points and were impossible for ancient people to melt. Thus, alloying (in particular, interstitial alloying) may also be performed with one or more constituents in a gaseous state, such as found in a blast furnace to make pig iron (liquid-gas), nitriding, carbonitriding or other forms of case hardening (solid-gas), or the cementation process used to make blister steel (solid-gas). It may also be done with one, more, or all of the constituents in the solid state, such as found in ancient methods of pattern welding (solid-solid), shear steel (solid-solid), or crucible steel production (solid-liquid), mixing the elements via solid-state diffusion.
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