Salt baths are not used by Nitrex due to that method’s environmental dangers and our concern for personal safety of the operators. 3). When properly performed, postoxidation creates a layer of black oxide (Fe3O4), that greatly increases the corrosion resistance of the treated substrate while leaving an aesthetically attractive black color. [7], Because of the cleaning issues the Joseph Lucas Limited company began experimenting with gaseous forms of ferritic nitrocarburizing in the late 1950s. Salt bath nitriding is a thermochemical process in which nitrogen and carbon are diffused simultaneously into the surface of the material. This allows for better control of the dimensional stability that would not be present in case hardening processes that occur when the alloy is transitioned into the austenitic phase. This porosity is used to contain lubrication. [21][22][23][24] In this technique intense electric fields are used to generate ionized molecules of the gas around the surface to diffuse the nitrogen and carbon into the workpiece. Salt Bath Nitriding/Nitrocarburizing was originally created as an alternative to gas nitriding that would produce a more uniform case through surface contact between the substrate and liquid salt. [9] Their process is the widely known as the Tufftride or Tenifer process. Tenoplus is a two-stage high-temperature process. [2] There are four main classes of ferritic nitrocarburizing: gaseous, salt bath, ion or plasma, and fluidized-bed. It is mandatory that the salt bath chemistry is checked at the commencement of each shift and the appropriate additions of salt are added to return the bath to its operational strength. Besides, the process has few advantages, quick heating of the workpiece being the only one worth mentioning. The surface hardness ranges from 800 to 1500 HV depending on the steel grade. Despite the naming the process is a modified form of nitriding and not carburizing. Unlike nitriding methods using a salt bath, gas nitriding is a more flexible process with easier disposal of the nitriding agent. The company applied for a patent by 1961. 2. [8], This spurred the development of a more environmentally friendly salt bath process by the German company Degussa after acquiring ICI patents. This also inversely affects the depth of the case; i.e. Ferritic nitrocarburizing (FNC) is a thermochemical surface hardening process that involves diffusion of both nitrogen and carbon into the part. [16], Other trademarked processes are Sursulf and Tenoplus. The Nitrocarburizing process step is conducted in the MEL 1 / TF 1 bath at 896-1166°F, the standard temperature is usually 1076°F. Numerous improvements and design enhancements have occurred over the years. The processes are broken up into four main classes: gaseous, salt bath, ion or plasma, or fluidized-bed. Liquid Nitriding (Salt Bath Nitriding) FAQ What is Liquid Nitriding? The shared attributes of this class of this process is the introduction of nitrogen and carbon in the ferritic state of the material. The processing temperature ranges from 525 °C (977 °F) to 625 °C (1,157 °F), but usually occurs at 565 °C (1,049 °F). Ferritic Nitrocarburizing in liquid salt bath Corrosion protection and wear resistance Meets or exceeds AMS 2753 Nitriding is a popular case hardening technique renowned for the qualities it delivers at relatively low process temperatures. It produced a similar surface finish as the Sulfinuz process with the exception of the formation of sulfides. [14][15], The process uses a salt bath of alkali cyanate. Salt Bath Nitriding/Nitrocarburizing is well known under various trade names, including ARCOR®, TENIFER®, TUFFTRIDE®, MELONITE®, and QPQ®. With the introduction of nitrogen in the diffused zone fatigue properties are enhanced. pre-heat, Del-Nite salt, Delamin Del-quench salt bath quench (SBQ), which produces a layer of epsilon iron nitride, Fig. The primary objective of ferritic nitrocarburising treatment is to improve the anti-scuffing characteristics of components. [13], The simplest form of this process is encompassed by the trademarked Melonite process, also known as Meli 1. [11], Salt bath ferritic nitrocarburizing is also known as liquid ferritic nitrocarburizing or liquid nitrocarburizing[12] and is also known by the trademarked names Tufftride[3] and Tenifer. Salt Bath Nitriding is a ferritic nitrocarburizing process which involves the diffusional addition of both nitrogen and carbon to the ferrous surface at temperatures within the ferritic phase. This is done to minimize distortion and to destroy any lingering cyanates or cyanides left on the workpiece. This process had faster cycle times, required less cleaning and preparation, formed deeper cases, and allowed for better control of the process. Ferritic nitrocarburizing or FNC, also known by the proprietary names Tenifer, Tufftride and Melonite as well as ARCOR,[Note 1][1] is a range of proprietary case hardening processes that diffuse nitrogen and carbon into ferrous metals at sub-critical temperatures during a salt bath. [30] Besides Glock several other pistol manufacturers, including Smith & Wesson and Springfield Armory, Inc., also use ferritic nitrocarburizing for finishing parts like barrels and slides but they call it Melonite finish. A salt bath uses a liquid salt solution that is usually heated between 750 degrees Fahrenheit and 1050 degrees Fahrenheit. [31], Plasma-assisted ferritic nitrocarburizing, Other trade names include Tuffride/ Tuffrider, QPQ, Sulfinuz, Sursulf, Meli 1, and Nitride, among others, https://www.youtube.com/watch?v=yt2DU-22qus, "To find the way in the nomenclature jungle of nitrogen diffusion", https://www.ahtcorp.com/services/nitriding-and-nitrocarburizing/ultraox/, MINIMIZING WEAR THROUGH COMBINED THERMO CHEMICAL AND PLASMA ACTIVATED DIFFUSION AND COATING PROCESSES by Thomas Mueller, Andreas Gebeshuber, Roland Kullmer, Christoph Lugmair, Stefan Perlot, Monika Stoiber, "Furnace Atmospheres 3: Nitrading and Nitrocarburizing", "Firearms History, Technology & Development", Tufftride-/QPQ-process: technical information, https://en.wikipedia.org/w/index.php?title=Ferritic_nitrocarburizing&oldid=995211950, Creative Commons Attribution-ShareAlike License, This page was last edited on 19 December 2020, at 20:51. Liquid Salt Bath Ferritic Nitrocarburizing Non-Cyanide Bath(STABILIZED Jul 2019) AMS2753D This specification covers the requirements for an epsilon-iron nitride case on ferrous parts produced by immersion in a low-temperature, agitated, fused salt bath. Liquid Nitriding (LN) is a common term for a diffusion process that is actually liquid nitrocarburizing; a thermo-chemical reaction whereby nitrogen, primarily, and some carbon are diffused into the surface of iron-based materials. The surface formed from the reaction has a compound layer and a diffusion layer. The process is gaining a great deal of popularity in North America due to legislation on process effluents, European engineering specifications and a growing awareness of the process repeatability and metallurgical consistency due to computer control (Fig. This is a crucial reason for the positive, specific surface zone properties of salt bath … It is 0.05 mm (0.0020 in) thick and produces a 64 Rockwell C hardness rating via a 500 °C (932 °F) nitride bath. Salt Bath Nitriding/Nitrocarburizing was originally created as an alternative to gas nitriding that would produce a more uniform case through surface contact between the substrate and liquid salt. The shared attributes of this class of this process is the introduction of nitrogen and carbon in the ferritic state of the material. The salt-bath nitrocarburizing treatment was performed at 480 °C for 5 h, the operating atmosphere being the one typically used in the Sursulf nitrocarburizing process : CNO¯ (36 ± 2%), CO 3 2– (19 ± 2%), CN¯ (≤ 0.8%). It is necessary to understand that there are two power-system types: continuous DC power a… It is a thermochemical diffusion process whereby nitrogen-bearing salts generate a controlled release of nitrogen at the interface of a ferrous part. It is used as a post-nitride ‘quench bath.’ This neutralizes any potential toxic compounds which may have formed as a result of nitriding bath reactions reacting with any nitriding salt residues adhering to the components or fixtures. The bath is then treated to convert the carbonate back to a cyanate. Houston Unlimited, Inc. offers a salt bath nitriding process, also referred to as liquid salt bath ferritic nitrocarburizing. Salt bath nitriding can be an economical method of nitriding providing that both the salt bath chemistry and the salt bath cleanliness are maintained. Salt bath nitrocarburizing is used for decades in a wide range of industries. The processes are broken up into four main classes: gaseous, salt bath, ion or plasma, or fluidized-bed. Such highly active gas with ionized molecules is called plasma, naming the technique. Due to the relatively low temperature range (420 °C (788 °F) to 580 °C (1,076 °F)) generally applied during plasma-assisted ferritic nitrocarburizing and gentle cooling in the furnace, the distortion of workpieces can be minimized. It is also known as Liquid/Salt Bath Ferritic Nitrocarburizing (FNC) process. This quench is held for 5 to 20 minutes before final quenching to room temperature. [20], The parts are first cleaned, usually with a vapor degreasing process, and then nitrocarburized around 570 °C (1,058 °F), with a process time that ranges from one to four hours. Due to the main process characteristics like Grandpower, a Slovakian firearms producer, also uses a quench polish quench (QPQ) treatment to harden metal parts on its K100 pistols. ISONITE® QPQ (per SAE AMS 2753) is a high-performance variety of salt bath nitrocarburizing process. [3], The process is used to improve three main surface integrity aspects including scuffing resistance, fatigue properties, and corrosion resistance. The trade name and patented processes may vary slightly from the general description, but they are all a form of ferritic nitrocarburizing. salt bath equipment NITRIDING SYSTEMS Since the introduction of salt bath nitriding (or ferritic nitrocarburizing) to North America in the 1950s, Kolene has been providing the … Liquid Nitriding / Salt Bath Nitriding (SBN) / QPQ /Ferritic Nitro-Carburizing (FNC) Liquid nitriding is a surface enhancement process with one of the longest track … Pistol manufacturer Caracal International L.L.C. [17], Gaseous ferritic nitrocarburizing is also known as controlled nitrocarburizing, soft nitriding, and vacuum nitrocarburizing or by the tradenames UltraOx,[18] Nitrotec, Nitemper, Deganit, Triniding, Corr-I-Dur, Nitroc, NITREG-C and Nitrowear, Nitroneg. The atmosphere consisted of ammonia, hydrocarbon gases, and a small amount of other carbon-containing gases. Despite the name, the process is really a modified form of nitriding with carbon added. It begins with the treating cycle of the nitrocarburizing segment, i.e. In combination with oxidation bath it improves corrosion resistance and reduces surface roughness. The outer layer of a steel part treated with the SBN/QPQ SM process is significantly harder than its core, and thus provides excellent wear protection. Del-Quench™ Standard is a proprietary salt consisting of alkaline nitrate and hydroxide compounds. The intermediate quench is an oxidizing salt bath at 400 °C (752 °F). The TENIFER process (TF1) is a salt bath nitrocarburizing of components in molten salt at temperatures around 580° C. Besides the addition of nitrogen, carbon also always diffuses into the surface in every TF1 treatment. Salt Bath Nitriding. The gas used for plasma nitriding is usually pure nitrogen, since no spontaneous decomposition is needed (as is the case of gaseous ferritic nitrocarburizing with ammonia). Salt Bath Basics. Typically, this process involves either a salt bath nitriding or nitrocarburizing to properly treat a barrel. It is used to improve wear resistance and fatique strength of cast iron, sintered iron and steel. Nitrocarburizing / Salt Bath Nitriding Ionic liquids offer a significant improvement in wear protection, sliding properties and fatigue strength on all kind of ferrous materials. Post-oxidation after nitriding combined with polishing produces coatings with exceptional appearance (black color) and high corrosion resistance (greater than electrolytic chrome plating). A subsequent oxidizing quenching produce a major increase in corrosion resistance. uses ferritic nitrocarburizing for finishing parts such as barrels and slides with the plasma-based post oxidation process (PlasOx). It has the added advantage of inducing little shape distortion during the hardening process. [26] Since the introduction of the Glock pistol in 1982, this type of nitrocarburizing with postoxidation finish has become popular as a factory finish for military style handguns. Stainless steel workpieces can be processed at moderate temperatures (like 420 °C (788 °F)) without the formation of chromium nitride precipitates and hence maintaining their corrosion resistance properties.[25]. The first stage occurs at 625 °C (1,157 °F), while the second stage occurs at 580 °C (1,076 °F). Heckler & Koch use a nitrocarburizing process they refer to as Hostile Environment. SBN/QPQ SM (salt bath nitriding), or Quench-Polish-Quench, is particularly important to oil field equipment and other manufacturers whose parts are subject to high levels of wear, friction, or erosion. This is because of the low processing temperature, which reduces thermal shocks and avoids phase transitions in steel. Ferritic Nitrocarburizing is the thermochemical process that simultaneously diffuses nitrogen and carbon into the surface of ferrous metals. The diffusion layer contains nitrides and carbides. salt bath nitriding equipment Since the introduction of salt bath nitriding (or ferritic nitrocarburizing) to North America in the 1950s, Kolene has been providing the necessary process equipment. Salt-bath nitrocarburized steel, sintered iron and cast iron parts have very good wear, corrosion and fatigue resistance, as well as enhanced sliding proper-ties. The first company to successfully commercialize the process was the Imperial Chemical Industries in Great Britain. Ferritic nitrocarburizing solves some of the problems of size change and distortion that are seen in higher temperature treatments. While the process was very successful with high-speed spindles and cutting tools, there were issues with cleaning the solution off because it was not very water soluble. The finish on a Glock pistol is the third and final hardening process. An additional step can be added to the nitrocarburizing process called postoxidation. Version 9 or later of Adobe Reader is required. Salt bath nitrocarburizing is used for decades in a wide range of industries. An added benefit of the process is minimal distortion due to short process cycle within the ferrite phase. What is the basic principle of Liquid Nitriding? In salt bath nitriding the nitrogen donating medium is a nitrogen-containing salt such as cyanide salt. Ion nitridingis also known as glow-discharge nitriding or plasma nitriding (Fig. Case hardening refers to the “case” that develops around a part that is subjected to a hardening treatment. [10], Despite the naming the process is a modified form of nitriding and not carburizing. The next step is a mechanical polish of the nitride layer, thus restoring the original surface finish. The cyanate thermally reacts with the surface of the workpiece to form alkali carbonate. [3][19] The process works to achieve the same result as the salt bath process, except gaseous mixtures are used to diffuse the nitrogen and carbon into the workpiece. The trade name and patented processes may vary slightly from the general description, but they are all a form of ferritic nitrocarburizing. When steel parts are placed into a preheated liquid salt, there is sufficient energy localized near the surface due to differences in chemical potential that then allows nitrogen and carbon species to diffuse from the salt into the steel substrate. The actual gas mixtures are proprietary, but they usually contain ammonia and an endothermic gas. Software Requirements: To view, complete, and print fillable PDF forms you'll need the freely available Adobe Reader software installed on your computer. (a) salt bath (liquid) nitriding, where the source of nitrogen (and also carbon) is molten salt. [27], Glock Ges.m.b.H., an Austrian firearms manufacturer, utilized the Tenifer process until 2010, to protect the barrels and slides of the pistols they manufacture. Other methods of ferric nitrocarburizing include gaseous process such as Nitrotec and ion (plasma) ones. Both types of nitrocarburization are used with steel and other iron alloy metals in a salt bath. Modern salt-bath plant Nitrocarburizing offers an alternative to complicated coating processes and enables manufacturers to replace expensive materials with less costly ones. During the process, a two-part surface layer is formed, an outer iron nitride layer with a nitrogen diffusion layer below it. a high carbon steel will form a hard, but shallow case. This process is preferred for improving tribological and surface properties of ferrous components in addition to improving fatigue strength. To ensure part quality, our salt baths are continuously monitored, with chemistry adjustments made when necessary. At this temperature steels and other ferrous alloys remain in the ferritic phase region. It is most commonly used on steels, sintered irons, and cast irons to lower friction and improve wear and corrosion resistance. In combination with oxidation bath it improves corrosion resistance and reduces surface roughness. Nitrocarburizing and carbonitriding sound somewhat similar and they perform similar functions: to make a workpiece surface harder by imparting carbon, nitrogen or both to its surface. PVD High Energy Deposition Coating Technology, Chrome / Chromium Carbide Coating (CrC-TDH), Plasma Electrolytic Oxidation (PEO) | CeraTough™, Corrosion resistance exceeds chrome plating, Oil & gas components such as impellers, diffusers, and pipe and drill pieces (i.e. Common applications include spindles, cams, gears, dies, hydraulic piston rods, and powdered metal components. [4], The first ferritic nitrocarburizing methods were done at low temperatures, around 550 °C (1,022 °F), in a liquid salt bath. In 2010 Glock switched to a gaseous ferritic nitrocarburizing process. Following this the ion nitriding process was invented in the early 1980s. ICI called their process "the cassel" due to the plant where it was developed [5][6] or "Sulfinuz" treatment because it had sulfur in the salt bath. [29] After the Tenifer process, a black Parkerized finish is applied and the slide is protected even if the finish were to wear off. Parts are typically core treated and finished machined prior to nitriding, with some allowance being made for a slight amount of growth. It is used to improve wear resistance and fatique strength of cast iron, sintered iron and steel. The compound layer consists of iron, nitrogen, and oxygen, is abrasion resistant, and stable at elevated temperatures. These processes are most commonly used on low-carbon, low-alloy steels, however they are also used on medium and high-carbon steels. [20], Plasma-assisted ferritic nitrocarburizing is also known as ion nitriding, plasma ion nitriding or glow-discharge nitriding. Sursulf has a sulfur compound in the salt bath to create surface sulfides which creates porosity in the workpiece surface. The process works to achieve the same result as the salt bath and gaseous process, except the reactivity of the media is not due to the temperature but to the gas ionized state. The compound layer exhibits significant improvement in adhesive wear resistance. Lower temperature cycles produce an S-Phase/Expanded Austenite case in stainless steels. It is a thermochemical diffusion process whereby nitrogen-bearing salts generate a controlled release of … The temperature used is typical of all nitrocarburizing processes: 550 to 570 °C. The process is carried out at 750-1050°F, making it faster than gas nitriding. ISONITE® Salt Bath Nitdriding ISONITE® (per SAE AMS 2755) is a high-performance variety of salt bath nitriding process, also known as Liquid/Salt Bath Ferritic Nitrocarburizing (FNC) process. [28] The final matte, non-glare finish meets or exceeds stainless steel specifications, is 85% more corrosion resistant than a hard chrome finish, and is 99.9% salt-water corrosion resistant. It is a range of proprietary case hardening processes that diffuse nitrogen and carbon into ferrous metals at sub-critical temperatures during a salt bath. This is contained in a steel pot that has an aeration system. drill heads), Treatment for mild steels, carbon steels, tool steels (A2, D2, M2, H13), and stainless steels (303, 304, 316), Development capabilities: specialty materials or components tailored to your specific application. [14], A similar process is the trademarked Nu-Tride process, also known incorrectly as the Kolene process (which is actually the company's name), which includes a preheat and an intermediate quench cycle. 2). The salts used also donate carbon to the workpiece surface making salt bath a nitrocarburizing process. Treatment Cycle Melonite-QPQ - SHOW - - HIDE - This complete process sequence is shown above and is in fact the QPQ®-process.