Feritic nitrocarbarication , also known as Tennifer / Tenifer and Melonite , is a range of case-specific hardening of nitrogen and carbon that diffuses into ferrous metals at sub-critical temperatures during bath salts. The processing temperature ranges from 525 ° C (977 ° F) to 625 ° C (1.157 ° F), but usually occurs at 565 ° C (1,049 ° F). At this temperature the steel and other iron mixtures are still in the ferritic phase, which is advantageous compared to the case hardening of other cases occurring in the austenitic phase. There are four main classes of ferritic nitritarburization: gas, salt bath, ion ion or plasma, and fluidized- bed .
This process is used to improve three major aspects of surface integrity including blister resistance, fatigue properties, and corrosion resistance. This has the additional advantage of inducing small form distortions during the hardening process. This is because of the low processing temperature, which reduces thermal shocks and avoids phase transitions in steel.
Video Ferritic nitrocarburizing
Histori
The first ferritic nitrocarburizing method was performed at a low temperature, about 550 ° C (1.022 ° F), in a bath of molten salt. The first company to successfully commercialize the process was Imperial Chemical Industries in the United Kingdom. ICI calls their process "cassel" because the factory where it was developed or "Sulfinuz" treatment because it has sulfur in bath salts. While the process is very successful with high speed spindles and cutlery, there is a problem with cleaning the solution because it is not very soluble in water.
Due to the cleaning issue, the company Joseph Lucas Limited began experimenting with ferrit nitritarburization gas forms in the late 1950s. The Company filed a patent application in 1961. This resulted in the same surface finish as the Sulfinuz process with the exception of sulphide formation. The atmosphere consists of ammonia, hydrocarbon gases, and small amounts of other carbon-containing gases.
This led to the development of a more environmentally friendly salt bath process by German company Degussa after obtaining ICI patents. Their process is widely known as the Tufftride or Tenifer process. After this the nitriding ion process was discovered in the early 1980s. This process has a faster cycle time, requires less cleaning and preparation, establishing deeper cases, and allow for better process control.
Maps Ferritic nitrocarburizing
Process
Although the naming process is a modified form of nitriding and not carburizing. The common attribute of this class of processes is the introduction of nitrogen and carbon in the ferritic state of the material. The process is broken down into four main classes: gummy bath salt , ion or plasma , or fluidized -bed . Patented trade names and processes may be slightly different from the general description, but they are all forms of ferritic nitritarburization. ferritic salt nitrocarburizing bath
The ferritic nitrocarburizing bath salts are also known as ferritic nitritarburization liquid or liquid bleaching nitrocarburizing and also known by the trademark name Tufftride and Tenifer >.
The simplest form of this process is covered by a trademarked Melonite process, also known as Meli 1 . It is most commonly used in steel, sintered iron, and cast iron to reduce friction and increase wear and corrosion resistance.
This process uses a salt bath from an alkaline cyanate. It is contained in a steel pot that has an aeration system. The cyan reacts thermally with the workpiece surface to form an alkali carbonate. The bath is then treated to convert the carbonate back into a cyanate. The surface formed from the reaction has a layer of the compound and the diffusion layer. The compound layer consists of iron, nitrogen, and oxygen, is abrasion resistant, and stable at high temperatures. The diffusion layer contains nitrides and carbides. The surface hardness ranges from 800 to 1500 HV depending on steel grade. It also affects the depth of the case; ie high carbon steels will form hard, but shallow cases.
A similar process is a trademarked Nu-Tride process, also known incorrectly as the Kolene process (which is actually a company name), which includes a preheating and intermediate cooling cycle. Medium quench is a bath of oxidizing salt at 400 ° C (752 ° F). This blackout is done for 5 to 20 minutes before the final cooling down to room temperature. This is done to minimize distortion and to destroy the remaining cyanide or cyanide left in the workpiece.
Other trademarked processes are Sursulf and Tenoplus . Sursulf has a sulfur compound in a salt bath to create a surface sulphide that creates porosity on the surface of the workpiece. This porosity is used to contain lubrication. Tenoplus is a two-stage high-temperature process. The first stage occurs at 625 Â ° C (1.157 Â ° F), while the second stage occurs at 580 Â ° C (1,076 Â ° F).
Nitrocarburizing ferritic gas
Nitrocarburizing ferritic gas is also known as nitrocarburizing controlled , soft nitriding , and vacuum nitrocarburizing or by the trade name Nitrotec , < b> Nitemper , Deganit , Sidewalks , Kor-I-Dur , Nitroc , NITREG-C and Nitrowear , Nitroneg . This process works to achieve the same results as the salt bath process, unless the gas mixture is used to diffuse the nitrogen and carbon into the workpiece.
The sections are first cleaned, usually by steam evaporation, and then nitrocarburized at about 570 ° C (1.058 ° F), with processing times ranging from one to four hours. The actual gas mixture is proprietary, but they usually contain ammonia and endothermic gases.
Nitrocarburizing assisted plasma ferritis
Plasma-assisted ferritic nitritarburization is also known as ion nitriding , nitriding plasma ions or nitriding-release lights . This process works to achieve the same results as bath salts and gas processes, except for media reactivity not due to temperature but to ionized gas. In this technique an intense electric field is used to produce ionized gas molecules around the surface to propagate nitrogen and carbon into the workpiece. A very active gas with ionized molecules is called a plasma, naming the technique. The gas used for nitriding plasma is usually pure nitrogen, because no spontaneous decomposition is required (as is the case of nitritarburization of ferritic gas with ammonia). Due to the relatively low temperature range (420 ° C (788 ° F) to 580 ° C (1.076 ° F)) is generally used during assisted ferritic nitritarburization of plasma and soft cooling in the furnace, the distortion of the workpiece can be minimized. Stainless steel workpieces can be processed at moderate temperatures (such as 420 ° C (788 ° F)) without the formation of chromium nitride precipitates and therefore maintain corrosion resistance properties.
Oxidized black oxidation
Additional steps can be added to the nitrocarburizing process called postoxidation. When done right, postoxidation creates a black oxide layer (Fe 3 O 4 ), which greatly increases the corrosion resistance of the treated substrate while leaving an attractive aesthetic black color. Since the introduction of the Glock gun in 1982, this type of nitrocarburizing with post-oxidation finish has become popular as a finished mill for military-style pistols.
Usage
These processes are most commonly used in low carbon steel, low alloy steel, but also used in high-strength steel and carbon. Common applications include spindle, cams, gear, dies, hydraulic piston rods, and powder metal components.
Glock Ges.m.b.H., Austrian firearm producer, utilizes the Tenifer process until 2010, to protect the barrels and slide pistols they make. The finish on the Glock gun is the third and final hardening process. It is 0.05 mm (0.0020 in) thick and produces a Rock hardness rating of C 64 via a 500 Ã, Â ° C (932 Ã, Â ° F) nitride bath. The final matte, non-glare finish meets or exceeds the stainless steel specifications, is 85% more corrosion resistant than the hard chrome finish, and 99.9% salt water corrosion resistance. After the Tenifer process, a black Parkerized finish is applied and the slides are protected even if completed to fade. In 2010 Glock switched to the nitrocarburizing process of ferritic gas. In addition to Glock some other pistol manufacturers, including Smith & amp; Wesson and Springfield Armory, Inc., also use ferritic nitrocarburizing to complete parts such as barrels and slides but they call it Melonite finish. Heckler & amp; Koch uses the nitrocarburizing process they call the Hostile Environment. Manufacturers of Caracal International Pistol L.L.C. using ferritic nitrocarburizing to complete parts such as barrels and slides by post-plasma oxidation process (PlasOx). Grandpower, the Slovak firearm producer, also uses quench polish quench (QPQ) treatment to harden the metal parts of its K100 pistol.
References
Bibliography
- Pye, David (2003), Nitridarburizing nitriding and practical ferritic , ASM International, ISBN 978-0-87170-791 -8.
- Pye, David. "About David Pye". Pye Metallurgical International Consulting . Retrieved January 10 2017 .
- Pye, David. "Book By David Pye". Pye Metallurgical International Consulting . Retrieved January 10 2017 . Joseph R. Davis (2001), Surface engineering for corrosion and wear resistance , ASM International, p.Ã, 115, ISBNÃ, 0-87170-700-4
External links
- Tufftride-/QPQ-process: technical information
- : What is Tufftride?
Source of the article : Wikipedia
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