Many old guns have faded color case hardening. Case hardening is a simple method of hardening steel involving the use of metal that has low carbon content, and combining it with a metal that has a higher carbon content. Having earned his Metallurgical Engineer degree there, McMillen and ART partnered with the school’s Research Foundation. At the furnace temperature, the added ammonia (NH3) breaks up or dissociates to provide the nitrogen to the surface of the steel. The operation resembles a transformer in which the primary or work coil is composed of several turns of copper wire and the part to be hardened is made the secondary of a high-frequency induction apparatus. Therefore, very quickly, a surface layer of high carbon (about 1.2 percent) is built up. What is case hardening? Thanks to further advances, it can now be done in a more aesthetic manner. H&M BlackNitride+ video demo sion methods and selective-hardening methods (Table 1). Cases as deep as 0.025 in can be produces by this method. Barium carbonate promotes the formation of carbon dioxide (CO2). In flame and induction hardening the steel must be capable of being hardened and therefore, the carbon content must be about 0.30 percent or higher. For these reasons, titanium hasn’t been used as extensively in firearms as its benefits would suggest. Krytos began by offering titanium AR-15 bolt carriers. Carburizing is the best method for low carbon steels. After quenching, the part should be stress-relieved by heating in the range of 350 to 400Â°F and air cooled. Many processes exist to change the properties of steel tools such tempering steel, oil quenching, precipitation hardening, and more. Since the core is of low carbon content, the carbon atoms trying to reach equilibrium will begin to diffuse inward. An endothermic gas atmosphere can be prepared by reaction of relatively rich mixture of air and hydrocarbon gas (usually natural gas) in an externally heated generator in the presence of a nickel catalyst. Traditional finishing like bluing still looks great but performance and high-wear environments demand more durability. Metal surface cleaning is the beginning of any metal treatment. The other method of case coloring is bathing the metal parts in cyanide. Cyaniding is a case hardening process that is fast and efficient; it is mainly used on low carbon steels. In this method, selected areas of the surface of a steel are heated into the austenite range and then quenched to form martensite. The people in ancient western civilization has invented this heat-treating process. The high-frequency induced currents tend to travel at the surface of the metal. This creates problems in applications where titanium would otherwise work well. Usually ships within 3 to 5 weeks. Both through hardening and sur-face hardening methods are reviewed. In conjunction with these university tech services, ART has an agreement to use their lab in exchange for royalty fees to further the university’s growth and fund student projects. Induction hardening. Usage of solvent‐based cleaners is declining. The heat treatment of gears is reviewed in Chapters 8 through 12. We took the known benefits of FNC and made it pretty. This is not an outer finish but a surface treatment. This extends the life of barrels and other parts by hardening the interior and exterior surface by treating them outside and inside. $92.82. The parts are then quenched and tempered. In step 1 of this new method, steel is case carburized and oil quenched; much higher than normal carburizing temperatures can be used. This procedure is used with relatively low temperature carbonitriding for the production of shallow case-depths in the range of 0.1–0.4 mm. 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. The first three methods change the chemical composition, carburizing by the addition of carbon, nitriding by the addition of nitrogen and cyaniding/carbonitriding by the addition of both carbon and nitrogen. After Your Steel Is Polished & Oil-Free, Apply COPPER F/X™ GEL Patina and Wipe Away With Wet Rag or Sponge. Depth of the hardness zone may be controlled by an adjustment of the flame intensity, heating time, or speed of travel. The method includes the steps of carburizing the article in a carburizing atmosphere at atmospheric pressure, heating the article in a vacuum for a predetermined period of time, and hardening the article. Degussa in Germany released their Tufftride/Tenifer process. A brief introduction addresses the progressive failure modes, focusing mainly on creep and stress corrosion cracking (SCC) in special steel structural members. Step 2 eliminates ret All of the carburizing processes (pack, gas, liquid) require quenching from the carburizing temperature or a lower temperature or reheating and quenching. Modern Browning and Winchester receivers are made from high-quality SAE 4140 steel which is heat-treated to a hardness of RC 38-42. Our process results in a more uniform look. Heating results from the resistance of the metal to passage of these currents. The steel is usually hardened and tampered between 1100 and 1300Â°F to produce a sorbitic structure of... Cyaniding and carbonitriding. The steel is usually hardened and tampered between 1100 and 1300Â°F to produce a sorbitic structure of maximum core toughness and then nitrided. Most carburizing gases are flammable and controls are needed to keep carburizing gas at 1700oF from contacting air (oxygen). bill aug 11, 2019 color case hardening, color case-hardening, faq's, latest news!, questions & answers, specialty finishes, tips & tricks, unique finishes 0 comment STEEL F/X® Patinas Specially Developed for Creating a Color Case-Hardened Finish. As H&M developed their process, the company introduced the technology to golf clubs and later expanded to firearms, finding it produces an excellent finish. The carburizing process does not harden the steel. The distinct coloring of color case hardening comes from uneven quenching. Depending on the frequency and amperage, the rate of heating as well as the depth of heating can be controlled. A nitrided case consists of two distinct zones. Blacknitride+™ and ArmorTi changes that notion. Since nitrogen increases the hardenability, carbonitriding the less expensive carbon steels for many applications will provide properties equivalent to those obtained in gas-carburized alloy steels. With a 50,000 square foot facility staffed with 50 employees in Akron, Ohio and an additional 20,000 square foot Glendale, Arizona facility staffed with five employees, H&M maintains its own in-house metallurgical research and development testing laboratory and FFL license. ... Have proper ventilation and use proper modern safety gear! The article also discusses various case depth measurement methods, including chemical, mechanical, visual, and nondestructive methods. By staying in the cooler ferritic phase and using a lower processing temperature, thermal shock is reduced and phase transitions in the steel are avoided. But when it comes to durability, case hardening is one of the best. In cyaniding, the case is higher in nitrogen and lower in carbon. However, as cyanide salts are poisonous, this method requires careful attention and the parts must be thoroughly washed after heat treatment to prevent rusting. Single-quench hardening. Hardening is a heat treatment process carried out to increase the hardness of Steel. Place parts in a vented steel container, pack compound around parts, seal container tightly, and heat to 1750° F. Single quench hardening is a special case hardening process. For reference, the company uses a vat for the drop-in dunk that is six-feet deep and 50 inches around. Therefore, it is necessary that the steel is capable of being hardened. Around 1400 BC, hardening methods began to appear in armouries around the world. CHERRY RED TR-CHER-5 Instant Case Hardening Compound 5 LB 4.8 out of 5 stars 5. Color case hardening uses similar techniques to achieve similar results. Color case hardening occurs when soft steels were packed in a reasonably airtight crucible in a mixture of charred leather, bone charcoal and wood charcoal. FNC improves surface integrity aspects by increasing corrosion and scuffing resistance as well as fatigue properties while inducing little shape distortion during the hardening process. A carbon content of 0.3–0.6 wt% C is needed for this type of hardening. One of their developments is a wear-resistant coating for the defense industry, a thermochemical diffusion hardening process for titanium. For application where lower hardness is acceptable, medium carbon steels containing chromium and molybdenum (AISI 4100 and 4300 series) are used. These processes are most commonly used on high-carbon, low-alloy steels. The exception to this has been in suppressors as they don’t have to deal with friction. Like H&M, Akron Research and Technology offers a custom shop for gunsmiths. Cyaniding and carbonitriding4. Shade McMillen explaining the Blacknitride process from their Glendale, AZ facility. Carbonitriding is a case hardening process in which a steel is heated in a gaseous atmosphere of such composition that carbon and nitrogen are absorbed simultaneously. Case hardening by carburising is one of the most common methods of thermal, or rather thermo-chemical, treatment. The combination of metals produces a product that is much harder. of modern knowledge about ancient case hardening methods of Indian blacksmiths. The process entails diffusion of boron atoms into the lattice of the parent metal and a hard interstitial boron compound is formed at the surface. The extra carbon is added to the surface of the part only, thereby making the surface of the part harder, but leaving the center of the part tough and malleable. This is achieved by case hardening. Titanium parts are first machined to dimension and then run through the process. Testing has demonstrated slides continue to hold up after tens of thousands of rounds fired. Induction hardening works best on parts small enough and suitable in shape to be compatible with the induction coil. Simply apply the hardening compound to your metal parts, heat to the required temperature, then quench in oil or water for a professional grade, heat-treatment. A STEM-focused institution, it focuses on polymers, advanced materials, and engineering. Nitriding is also applied to stainless steels and tool steels for certain applications. Blacknitride+ for steel and ArmorTi for titanium are great options to consider for your firearm projects. This type of case coloring is common among Italian guns, such as the Caesar Guerini Woodlander at the top of the picture. The reverse is true in the case of carburizing. Titanium has a reputation for deforming under impact. The carburizing time is between 4 to 10 hours. The reaction of nitrogen with the steel causes the formation of very hard iron and alloy nitrogen compounds. Unlike other options, ArmorTi changes the metallurgy of the outer layer of the titanium by diffusing interstitial hardening elements into the surface instead of applying a new material to the outer surface of the titanium. Aluminium, chromium and molybdenum are the major nitride-forming alloying elements. Not only because they can’t promise to be familiar with every possible firearm but because Blacknitride+ will surface harden everything inside and out. Diffusion methods may allow effective hardening of the entire surface of a part and are generally used when a large number of parts are to be surface hardened. In this method, the material is placed in a bath of molten cyanide so that carbon will diffuse from the bath into the metal and produce a case comparable with one resulting from pack or gas carburizing. Case Hardening Methods Carburizing. Depending on the physicochemical state of the medium that contains the diffusing element, chemical case hardening can be carried out from the gas, liquid, solid, or vapor phase (the first two are carried out the most frequently) in gas, vacuum, or tank furnaces on objects made of steel, cast iron, pure metals, and alloys based on nickel, molybdenum, tungsten, cobalt, niobium, copper, aluminium, and other … The lower thermal conductivity of titanium makes it more difficult for the heat to transfer into a titanium part, keeping it cooler longer and cooling faster once it becomes hot. Color case hardening services use bone charcoal to heat the steel to approximately 950 degrees Celsius before quenching the steel. The combination of a hard surface and a soft interior is greatly valued in modern engineering because it can withstand very high stress and fatigue, a property that is required in such items as gears and anti-friction bearings. This results in the materials beginning to “stick” to each other and eventually completely binding. Pack-In Surface-Hardening Compounds for Steel Harden carbon steel parts in batches, creating wear-resistant surfaces. The parts to be nitrided are placed in an airtight container through which the nitriding atmosphere is supplied continuously. There is no technical limit to the depth of hardening with carburizing techniques, but it is not common to carburize to depths in excess of 0.050 in. Generally, steel for flame hardening have 0.3 to 0.6 percent carbon. Common applications include spindles, cams, gears, dies, hydraulic piston rods, and powdered metal components. Hayward A. Harvey, (born Jan. 17, 1824, Jamestown, N.Y., U.S.—died Aug. 28, 1893, Orange, N.J.), versatile American inventor who discovered the modern method of strengthening armour plating.. Harvey began his career as a draftsman in the New York Screw Company, of which his father was president. Because it is a surface-hardening treatment, there are no dimension changes or flaking, chipping, peeling, or loss of adhesion under heavy loading after wear. Under known and standard operating conditions, with the surface at fixed carbon concentration, the form of carbon gradient may be predicted, with reasonable accuracy, as a function of elapsed time. Modern heat treatment of metals and alloys encompasses, in addition to heat treatment proper, thermomechanical treatment, chemical-mechanical treatment, and chemical heat treatment. Flame hardening5. The atmospheres used in carbonitriding generally comprise a mixture of carrier gas, enriching gas and ammonia. Case hardening is being practiced in western countries for a long times. method 1: using gel patinas. The main disadvantages are the possibility of overheating and thus damaging the part and difficulty in producing hardened zones less than 1/16 inch in depth. After making the same type of arrangements, gunsmith can have their titanium guns and parts finished with ArmorTi. Case hardening consists of adding carbon to a low carbon steel. Generally, carbon content of the case is lower than that produced by carburizing, ranging from about 0.5 to 0.8 percent. The equipment can be taken to the job and adjusted to treat only the area which requires hardening. The carburizing compound is in the form of coarse particles or lumps so that when the cover of the container is sealed, sufficient air is trapped inside to form carbon monoxide. The rate of diffusion of carbon in austenite, at a given temperature, is dependent upon the diffusion coefficient and the carbon concentration gradient. Ferritic nitrocarburizing (sometimes abbreviated FNC) is a case hardening processes that diffuses nitrogen and carbon into ferrous metals at sub-critical temperatures during a salt bath. Actually carbonitriding is a modification of carburizing process. ( Log Out / Protective coatings designed for steel can’t accommodate titanium’s lower stiffness. The hardened zone is generally much deeper than that obtained by carburizing, ranging from 1/8 to 1/4 inch in depth. These processes are commonly used on low-carbon, low-alloy steels, however they can also be used on medium and high-carbon steels. Because of inherent variation in case depth, the method is not used on work requiring a case depth of less than 0.030 in. and tolerances are at least 0.010 in. Case hardening is a simple approach that hardens the surface of a material by infusing elements into the metal. Diffusion methods modify the chemical composition of the surface with hard-ening species such as carbon, nitrogen, or boron. This process is not new and always held potential for firearm parts. While any material will either deform or break under sufficient impact, titanium has a lower stiffness than steel, allowing it to see lower impact stresses than steel under the same conditions. This process can minimize wear and tear and increase the strength of the steel parts’ surface. Just to send the point home, Blacknitride+ will degrade and eat aluminum. The process dates back to experiments in the 1950s. Case hardening describes lumber or timber that has been dried too rapidly. Galling is a form of wear caused by welding between two surfaces due to friction. Case Hardening is a metal surface process also referred to as surface hardening. for cyaniding and up to 0.030 in. The relation of time and temperature to case depth is shown in the figure given below. The main advantages of flame hardening are adaptability and portability. The range of frequencies commonly used is between 10,000 and 500,000 Hz. important method for the manufacture of plastic gears, is covered in Chapter 4. Let’s look at the multiple methods used in the ste… This method is efficient and economical for individual processing of small lots of parts or of large, massive parts. Subscribe now or renew your subscription. Parts too large to be placed in a furnace can be handled easily and quickly with the torch. There are five principal methods of case hardening as under. This process is particularly used for parts requiring a very thin hard case, such as screws, small gears, bolts and nuts. It is an ancient technology that goes back to approximately 1400BC. There are certain metals like iron or steel, that have very low hardness. “Success for this process takes real effort to obtain our internal high standards,” McMillen explains. Chemical hardening methods- Ammonia, vinegar, alcohol(s), acetone, brine Mechanical hardening methods- Hammering “Stabilizing” methods- Beeswax, Stearic acid, “Pitchwax”, Gelatin, Elmer’s This produces a very hard and surface abrasion-resistant element, while at the same time Wood initially dries from the shell (surface), shrinking the shell and putting the core under compression. The process works best when large volumes are shipped, which makes the process more affordable. ( Log Out / McMillen started Akron Research and Technology (AkronRT.com, 330/745-3075) to address these issues. The container is heated to the proper temperature for the required amount of time and then cooled slowly. In gas carburizing, the steel is heated in contact with carbon monoxide and/or a hydrocarbon which is readily decomposed at carburizing temperature. Therefore, since additional hardening was not required, case colors were the main objective in case hardening the receiver, lever, butt plate, and grip cap. This crucible was heated to 1,350 °F (730 °C) for up to 6 hours (the longer the heat was applied the thicker the case hardening). Processing at a temperature of over 1,000°F where ferrous alloys and steel are in a ferritic phase provides advantages over other case hardening processes that occur in the hotter austenitic phase. Work coil of different designs are used to suit different types of heating requirements like external heating, internal heating, etc. It involves diffusive infiltration of carbon from the surface inwards and subsequent quenching of the layer thus formed. Finishes such as PVD (Physical Vapor Deposition) or Cerakote are actually ceramic coatings applied on the surface’s outside rather like a hard candy shell. Titanium is a great material for gun building as it is light and strong but the friction is bad, galling is a big problem, and there are issues with impact damage. After diffusion has taken place for the required amount of time depending upon the case depth desired, the part is removed from the furnace and cooled. “FNC was never intended for aesthetics and the process makes it difficult to achieve uniformity. An accurate and repeatable method of measuring case depth is essential for quality control of the case hardening process and for evaluation of workpieces for conformance with specifications. Food dehydrators—either commercially made or homemade—give a good-quality dried product. Sorry, your blog cannot share posts by email. ART develops metallurgical solutions for many industries, including aerospace, automotive, defense, energy, food, medical, mining, oil/gas, and steel. Where extreme wear characteristics are important, but aesthetics are not, FNC has been a proven choice. Due to this, the entire pack is cooled slowly and the part is subsequently hardened and tempered. Blacknitride+ treats inside the metal so there are no dimensional changes to the fitted parts and no build up in threaded holes or slide-to-frame fit. In cyaniding, the proportion of nitrogen and carbon in the case produced by a cyanide bath depends on both composition and temperature of the bath, the temperature being the most important. Flame or induction hardening are processes in which the surface of the steel is heated very rapidly to high temperatures (by direct application of an oxy-gas flame, or by induction heating) then cooled rapidly, generally using water; this creates a "case" of martensite on the surface. In 1948, the family grandfather bought an interest in the company and in the late 1980s, the factory expanded its capabilities to provide salt bath nitriding. Therefore, it is possible to heat a shallow layer of the steel without heating the interior. Cycle times for liquid cyaniding is much shorter (1 to 4 hours) than gas and pack carburizing processes. Afterwards, the parts were removed from the furnace and quenched. Each work order is a customized process for those components shipped to the factory. Temperature within or above its critical range civilization has invented this heat-treating process services bone... To keep carburizing gas at 1700oF from contacting air ( oxygen ) type of Surface-Hardening treatment finish. Transfer heat massive parts carburizing compound in a furnace can be controlled caused by welding between two surfaces to... Were removed from the resistance of stainless steel is capable of being hardened process. Less than 0.030 in outer zone, nitride forming elements, including chemical,,! Aluminium alloy steels known as dry cyaniding, the price for a bulk savings a product that is six-feet and... Produced, up to a maximum of about 0.002 inch, is in! 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The carbon out of 5 stars 5 ArmorTi for titanium the equivalent of blacknitride+ for steel harden carbon steel,.