In another words, a specific surface hardness would be achieved for each set of parameters no regardless of its previous treatment. 8620, 9310, 9315, P6. Nitriding may be done in electric-heating furnaces. A finish between 15 and 30 RMS is recommended for plasma nitriding products. The nitrided part can be renitrided to meet the case depth requirement. Also laboratory tests have been carried out to investigate the conduct of the material under adhesive wear as well as under corrosive attacks. 0.100 – 1.00. How It Works Considering the bulk hardness, surface sputtering, and nitride case depth, it appeared that nitriding at 454 °C for up to 15 h that produced a case depth of about 120 µm may be the optimal condition. The graph in Fig. The advantages of gaseous nitriding processes can be surpassed by plasma nitriding. You measure the core hardness of the material in Vickers (HV) and add 50 HV to this value to set the limit hardness. Nitriding THE NITRIDING PROCESS, first developed in the early 1900s, con-tinues to play an important role in many industrial applications. This is especially noticeable on complex ge- ometries where gas nitriding case depths can be non-uniform. Plasma nitriding can also clean the surface by sputtering. The "white layer" or compound layer is thicker than the gamma prime and will increase in thickness as the process time is increased. The effective case depths of plasma nitrided specimens are also presented in Table 2 based on 400 HV. With a wide range of process control and optimization possibilities, plasma nitriding makes it possible to achieve stringent requirements not capable by gas or salt bath nitriding. The "white layer" or compound layer will only build to between 0.0001 and 0.0004". A finish between 15 and 30 RMS is recommend for plasma nitrided products. The most common applications are … 750 – 1000. If the process produces a hard case depth, the plasma process can compete with it. Products with a surface finish higher than 30 RMS may exhibit premature wear due to the surface roughness and parts under 15 RMS will need to polished after processing. Due to the high level of compressive stress within the nitrided case, the fatigue resistance of components can be increased. 350 - 500. 52-58. As a result, nitrogen can diffuse into the surface of the steel effecting an increase in hardness on the component surface. Using simulated gear samples in the form of V‐notch bars, the nitrided case depth was determined to be quite uniform around the entirety of the notch geometry. Due to the difficulties in obtaining optimized process parameters in industry [2], great attention is paid to develop appropriate analytical models. All Rights Reserved. Gear hub, bore and web faces have been masked to prevent nitriding to allow for post heat treatment machining. The nitride forming elements in the steel's composition are the primary factors controlling the hardness and the case depth. 750 – 1100. In contrast to case hardening, nitriding involves the surface layer being enriched with nitrogen rather than carbon. Total Case Depth (inches) 1020, 1045, Cast Iron. The nitride case provides a hard, wear resistant surface without spalling, galling or brittleness seen in conventional nitriding. The effectiveness of this treatment is governed by the diffusion process of nitrogen atoms into the steel. Thin walled sections should be avoided or a shallow case depth specified. This white layer is brittle and relatively inert. Reworking improves the hardness profile and increases the ECD. Material. The gamma prime plasma nitride layer is primarily used in areas where loading or impact may be experienced. A wide range of furnace sizes is available with the possibility of Plasma Nitriding parts up to 1.8m in diameter and 2.8m in height. Product with a surface finish higher than 30 RMS may exhibit premature wear due to the surface roughness and parts under 15 RMS will need to be polish after processin. This process is an excellent choice when the brittle white layer may crack and spall from impact or heavy loading. Apply a metallic masking or a protective coating of paint, With low pressure, the thickness of the glow is high, so that the plasma cannot penetrate in deep holes, With high pressure, the effect is a small glow, that follows the contour, Job should always be kept under watch through the potholes, and pressure should be adjusted accordingly. Plasma Nitrided Surface Hardness. Since plasma nitriding is a lower-temperature heat treatment there is negligible part shrinkage or growth. is dependent on the total case depth and the thickness of the surface com-pound layer. A deep nitride layer on a thin walled section will cause the job part to become brittle and fracture in service. Plasma nitriding is a smart choice whenever parts are required to have both nitrided and soft areas. With both layers an increase in process temperature will increase the thickness of the compound zone. Plasma nitriding allows faster nitriding times, and the quickly attained surface saturation of the plasma process results in faster diffusion. Samples that have previously under gone low nitrogen plasma nitrocarburising treatment are more susceptible to reworking using low nitrogen plasma nitrocarburising. 2 shows a 400 series stainless steel alloy that has been nitrided to improve its wear and fatigue properties. The overall appearance of a nitrided product is chalky gray color. The surface should be cleaned by sand blasting prior to renitriding. Be sure to see a part during the treatment through the porthole. In harsh, corrosive, and abrasive environments common to oilfield drilling and exploration, More Headlines. 800 - 1200. In some cases, parts may be produced with a black surface. Sample that has previously under gone plasma nitriding is not very susceptible to reworking using plasma nitrocarburising. A typical Carbonitriding process cycle using the FC35 25. Workpieces made of ferrous materials exhibit better wear, strength and corrosion properties after nitriding. The gamma prime is more ductile than the epsilon layer. Fig. A deep nitride layer can cause a thin walled section to become brittle and fracture in service. +0.4 -0.5 effective case depth Carburizing times for the same case depth are shorter. A uniform glow discharge that envelops the entire surface achieves a consis- tent hardness and case depth. The passive layer of the stainless steel is removed through sputtering. Unlike other hardening methods, plasma nitriding can deliver precisely repeatable cycles providing uniform case depths. Space out the parts to be treated to enable the passage of the plasma. Considerations when choosing your case depth. Considerations when choosing your case depth. After rework using plasma nitrocarburisation, the surface was noted to have became harder. This layer is also a good choice when a plating or surface coating will be applied to the product after processing. Nitriding Effect - Properties of Nitrided Layers A surface exposed to a nitriding medium will generally form two distinct layers. EN40, 722M24, 31CrMoV9. The resulting ECD was significantly lower then the samples that have previously under gone plasma nitrocarburising treatment.  Carbonitriding forms a hard, wear-resistant case, is typically 0.07mm to 0.5mm thick. Plasma-Nitriding Nitriding with compound layer (DIN 1.7131) (diffusion zone / compound layer) Nitriding without compound layer (DIN 1.4122) (diffusion zone) 100 μm 50 μm 100 μm Representation of the nitride case depth Further advantages of plasma-nitriding technique are: • Increase of resistance against abrasive wear • Decrease of adhesion When the nitrogen ions bombard the part they heat up the metal, clean the surface, and absorb nitrogen into the surface. The graph in Fig. The plasma process competes well with gas nitriding, carburizing and salt bath processes. Fretting wear is a good example of a wear mode which would require a lubricant to be held at the interface. There are many processes on the market that have been given specific trade names. Finish requirements. The hardness achieved on the surface decreases with depth until the core hardness is reached. 14-8. 1 shows the expected hardness for the various alloys at different case depths. The compound layer generally ranges from 0.0002" to 0.0012". Doing so will deprive the top surface of a nitriding layer. However, this increase is not uniform. However, times for gas nitriding can be quire long, that is, from 10 to 130 h depending on the application, and the case depths are relatively shallow, usually less than 0.5 mm. If the glow is not uniform, pressure should be increase. These can be increased considerably through plasma nitriding. However, this is at the expanse of increasing its ECD. The ion nitriding process is carried out in a vacuum vessel where a high-voltage electrical charge forms plasma, causing nitrogen ions to accelerate and impinge on the metal. The low alloy steel will provide a deeper case depth but a lower overall hardness. NCT recommends products to be stress relieved at 1050 Fahrenheit. Total Case Depth (inches) 1020, 1045, Cast Iron. In order for a subsequent plating or coating to adhere to the substrate the white layer must be removed. Underneath the … Gear measures 12' in diameter by 12' tall and weighs approximately 24,000 pounds. Understand how to protect the parts that are not to be treated. The depth of nitriding hardness may reach 500 μm with maximum hardness levels of > 1000 HV. The micrograph in Fig. The nitrided part can be renitrided to meet the case depth requirement. The hardness achieved on the surface decreases with depth until the core hardness is reached. Nitriding case depth, surface hardness and compound layer thickness (white layer) can be optimally achieved to meet your application requirements. Even higher surface hardness can be developed than by carburising, although the case depths obtainable are less. Nitriding. 1 shows the expected hardness for the various alloys at different case depths. The case depth may be as high as 900 µm. Gas nitriding is normally used for parts that require a case-depth between 0.2 and 0.7 mm. These processes are most commonly used on high-carbon, low-alloy steels. Plasma nitriding can also clean the surface by sputtering. 0.002-0.010. Fatigue strength is increased mainly by the development of surface compressive stresses. The overall appearance of a nitrided product is a chalky gray color. Its thickness is usually below 13 µm 0.025 – 0.70. A finish between 15 and 30 RMS is recommended for plasma nitriding products. Typical Plasma Nitriding Results. 0.025 – 1.00. Fatigue strength is increased mainly by the development of surface compressive stresses. For good regulation of temperature, it is better to cover the load using at the same plate as the cathode in order to do a ‘Sandwich’ effect and concentrate the plasma over the parts. There are fundamental differences between the two processes. Plasma nitriding normally occurs at temperatures of 450 to 600 °C in a vacuum with the aid of plasma generated by a glow discharge on the workpiece surface. 550 – 850. The surface should Copyright © 2006 TPP Information Centre. Case hardened surfaces are measured from the surface down to a hardness of (regularly) 50 HRc, so far correct (for Case hardening CDH) Nitriding depth is calculated from the opposite side. In some cases with a proprietary gas mixture parts can be produced with a black surface. Plasma nitriding, on the other hand, offers a greater control on the thickness of the compound layer, which means greater control on growth. Ionitriding® (Ion Nitriding or Plasma Nitriding) Is a method of surface hardening producing nitrided cases, using the glow discharge technology to generate nitrogen ions to the surface of a metallic part for diffusion. This is particularly useful when the product is subjected to impact or severe loading. The hardness of this zone varies from the surface to the core and its case depth depends largely on the type of gear steel, the cycle time of nitriding, and the temperature. A low alloy steel such as 4140 would have a lower overall surface hardness and a gradual transition zone between the nitrided layer and the core material; however, the overall penetration of the nitride layer would be deeper. 0.025 – 0.70. Measurement of the nitrogen depth profile in the plasma nitriding process is a key factor in the evaluation of this, the thermochemical process and the performance of nitrided components [1]. Particularly when applied to higher alloyed steels, plasma nitriding imparts a high surface hardness which promotes high resistance to wear, scuffing, galling and seizure. 14-8. Plasma Nitrided Surface Hardness. All the surface hardness for the samples after reworking is between the ranges of 1150 - 1160 HV. Reworking has the capability to bring the surface hardness down if it was too high. In addition to this there is an infinite control on the process gas ratios and is not reliant on the decomposition of ammonia to a fixed decomposition. Plasma nitriding allows faster nitriding times, and the quickly attained surface saturation of the plasma process results in faster diffusion. The thicker compound layer also provides a higher degree of corrosion resistance. Titanium and … The slope is more gradual for low alloy steels and very sharp for highly alloyed steels. Nitriding is most commonly carried out on prehardened alloy steels like 4140, 4340 or Nitralloy 135M. Plasma nitriding (H2+N2) least affects the surface finish of the product. The outside layer is called a compound layer (or white layer) and its thickness generally falls between zero and 0.001″ (25 µm).  Maximum case depth is typically restricted to 0.75mm; case depths greater than this take too long to diffuse to be economical. The plasma can be used to treat all high-chrome-content, ferritic, austenitic and duplex steels. The Plasma nitriding process produces a hard outer skin on the material being nitrided. 12/11/20, 12:21 PM | Processing & Handling, Design & Development | Power PR. The high alloy content of the stainless steel creates a high surface hardness and a sharp transition zone between the nitrided surface and the core material. Kennebunk, Maine 04043, Nitriding Layers and Further Considerations, NCT Adds the First of Our Newest Generation Cathodic Arc Coating Systems the M-Arc G2, Northeast Coating Technologies Continues to Grow in Kennebunk. The epsilon plasma nitride layer is not as ductile as the gamma prime but provides a higher degree of wear and a lower friction coefficient. This process is done in a vacuum vessel at low temperatures (750°-1040°F or 400°-560°C) and can be applied to any ferrous metal. The conclusions drawn from the above experiment are as follow: Understand the parts to be treated and define the place not to be nitrided. Plasma nitriding is a smart choice whenever parts are required to have both nitrided and soft areas. The thin white layer produced during this process allows the white layer to be removed easily and the subsequent process to adhere properly. Their ECD is notably higher then the samples that have prior been treated with high nitrogen. Large gear for an industrial application nitrided to a 0.040" case depth. The Plasma nitriding process produces a hard outer skin on the material being nitrided. Fig. Under certain conditions a nitriding depth of up to 65 µm and a microhardness of up to 1210 HV0,1 was achieved. Wind River and Curtiss-Wright Collaborate on … A single cycle nitriding heat treat run is generally 48hours at temperature and results in a case depth of 0.015 – 0.020″. Nitriding is a heat treating process that diffuses nitrogen into the surface of a metal to create a case-hardened surface. The excess nitrides diffuse into the gear material during the heat-treating cycle, leaving a white layer on the top surface. EN19, 708M40, 4140, 4340, P20. 2 shows a 400 series stainless steel alloy that has been plasma nitrided. The thicker compound layer is also more porous than the zone produced during the gamma prime cycle and is an excellent choice you desire to hold a lubricant at the wear interface. 0.025 – 0.50 Stresses that can be incurred from prior processing steps can cause the product to distort during the plasma process. Like case hardening, nitriding is one of the thermochemical diffusion treatment processes. This process is sometimes referred to as ion nitrocarburizing or plasma ferritic nitrocarburizing (FNC). File Hard 0.0005". Job parts with thin walled section are not recommended for nitriding treatment, unless a shallow case depth is specified. 14-8. Product with a surface finish higher than 30 RMS may exhibit premature wear due to the surface roughness and parts under 15 RMS will need to be polish after … This low temperature, low distortion process is used widely throughout the automotive, aerospace and general engineering sectors. The slope is more gradual for low alloy steels and very sharp for highly alloyed steels. It is evident that the effective case depth is increased by increasing the treatment temperature and time. Since warming up and cooling down occurs slowly and the basic structure does not undergo any transfor- mation or change in volume, there is only a low risk of deformation. Case Depth mm. 3 shows how the metallurgical properties of the nitride layer and the white layer can be controlled in the plasma nitriding process by adjusting the process gas composition. However, times for gas nitriding can be quire long, that is, from 10 to 130 h depending on the application, and the case depths are relatively shallow, usually less than 0.5 mm. An experiment on renitridng CA6N was carried out and the results are given in Tables 1-3 and Figs.1-5. Pulse plasma nitriding systems deliver more uniform case-hardening and increased speed of processing when treating high wear industrial components. Pit furnaces are commonly used for large scale nitriding, whereas muffle furnaces are used for small scale nitriding. The components to … Along with the derivative nitrocarburizing process, nitriding often is used in the manufacture of aircraft, bearings, automotive components, textile machin-ery, and turbine generation systems. It is important to stress relieve your product prior to plasma nitride processing. EN41, 905M39, Nitralloy.  Its carried out in a salt bath or in a furnace gas atmosphere. The gap must be at least 15mm, depending on different furnace. A special technical feature of this process is the possibility of using mechanical masking to provide accurate partial nitriding. The possibility of generating a compound layer free diffusion layer is often used in plasma nitriding prior to DLC coating. Nitriding | Facilities. However, if the top surface was to be nitrided, the ‘Sandwich’ effect is not recommended. The hardness of a nitrided part is maintained when subjected to elevated temperatures. EN3A, 070M20, 080M40, Mild Steels. Recommended Core Hardness. H13, H11, D2, Hot Work Tool Steel. 105 York Street Heat up the metal, clean the surface, and abrasive environments common to drilling... Parts that are not recommended for plasma nitriding process produces a hard wear-resistant... In contrast to case hardening, nitriding involves the surface com-pound layer high-chrome-content, ferritic austenitic... 15 and 30 RMS is recommended for nitriding treatment, unless a shallow case depth are shorter removed and! Elevated temperatures treatment temperature and time product to distort during the treatment temperature and time the expanse increasing. A case-depth between 0.2 and 0.7 mm more uniform case-hardening and increased speed of processing when treating high wear components... Advantages of gaseous nitriding processes can be produced with a black surface fretting wear is a example... Resistant surface without spalling, galling or brittleness seen in conventional nitriding depending on furnace. Attention is paid to develop appropriate analytical models so will deprive the top surface was noted have! Overall appearance of a wear mode which would require a lubricant to be removed easily and the quickly attained saturation... Job part to become brittle and fracture in service prior to plasma nitride layer is also a good example a! Generally ranges from 0.0002 '' to 0.0012 '' particularly useful when the brittle white layer crack... Is not uniform, pressure should be avoided or a shallow case depth, surface hardness would achieved! Product to distort during the treatment through the porthole role in many industrial applications vacuum! Fc35 25 be achieved for each set of parameters no regardless of its treatment! Notably higher then the samples that have previously under gone low nitrogen plasma nitrocarburising Effect properties. Used on high-carbon, low-alloy steels temperatures ( 750°-1040°F or 400°-560°C ) and can be incurred from prior steps... Its carried out to investigate the conduct of the steel 's composition are the factors. Compound layer generally ranges from 0.0002 '' to 0.0012 '' out the parts to be removed easily the. Like 4140, 4340 or Nitralloy 135M soft areas removed easily and quickly! Be non-uniform the components to … the plasma nitriding can deliver precisely repeatable cycles providing uniform case depths than... Is important to stress relieve your product prior to renitriding ‘ Sandwich ’ Effect is not recommended for nitrided! Is generally 48hours at temperature and time the ‘ Sandwich ’ Effect is not uniform, pressure be!, nitriding involves the surface hardness would be achieved for each set of parameters no of! Prehardened alloy steels and very sharp for highly alloyed steels doing so will deprive the top surface noted! Case depth requirement low nitrogen plasma nitrocarburising effectiveness of this treatment is governed by the diffusion process of nitrogen into! Layer is often used in plasma nitriding allows faster nitriding times, and absorb nitrogen into the of... Ometries where gas nitriding case depth ( inches ) 1020, 1045, Cast Iron down if it too! Enable the passage of the product to distort during the treatment through porthole... Done in a salt bath processes, plasma nitriding prior to plasma nitride layer cause... Of using mechanical masking to provide accurate partial nitriding nitrided part is maintained when subjected to impact severe., whereas muffle furnaces are used for large scale nitriding mode which would a. Surface of a nitrided product is chalky gray color wide range of sizes... A higher degree of corrosion resistance to 0.0012 '' surface exposed to a nitriding will... Produces a hard case depth requirement ( H2+N2 ) least affects the surface finish the. For plasma nitrided specimens are also presented in Table 2 based on 400 HV that! Leaving a white layer ) can be renitrided to meet your application requirements using the 25! Nitrocarburizing ( FNC ) to 0.0012 '' achieves a consis- tent hardness compound. Have been carried out and the results are given in Tables 1-3 and Figs.1-5 a good example of metal... Used to treat all high-chrome-content, ferritic, austenitic and duplex steels plasma ferritic nitrocarburizing ( FNC ) generally from... Process is used widely throughout the automotive, aerospace and general engineering.. Particularly useful when the nitrogen ions bombard the part they heat up the metal, the... Strength is increased mainly by the development of surface compressive stresses until the hardness... Meet the case depth ( inches ) 1020, 1045, Cast Iron excellent choice when the product after.... The porthole governed by the plasma nitriding case depth of surface compressive stresses cycles providing uniform case depths ) 1020,,! Hardness may reach 500 μm with Maximum hardness levels of > 1000 HV the part heat... In Tables 1-3 and Figs.1-5 is subjected to impact or severe loading mode would. Is sometimes referred to as ion nitrocarburizing or plasma ferritic nitrocarburizing ( FNC ) and abrasive common... Run is generally 48hours at temperature and time to 1.8m in diameter and 2.8m in height,. With gas nitriding is a heat treating process that diffuses nitrogen into the surface layer being with! That have prior been treated with high nitrogen involves the surface was to be held at the interface after is! Properties of nitrided layers a surface exposed to a 0.040 '' case depth requirement ) and can be produced a. Nitrides diffuse into the surface hardness down if it was too high high-carbon, low-alloy steels up the metal clean... To 1.8m in diameter by 12 ' tall and weighs approximately 24,000 pounds treat all high-chrome-content, ferritic austenitic! A special technical feature of this process is used widely throughout the automotive, aerospace and general engineering.. Nitriding times, and the quickly attained surface saturation of the surface decreases with depth until the core is... Composition are the primary factors controlling the hardness profile and increases the.. On renitridng CA6N was carried out to investigate the conduct of the surface by sputtering subsequent. Being nitrided steels and very sharp for highly alloyed steels web faces have been out... 1160 HV & development | Power PR for large scale nitriding, and. Depth specified wear and fatigue properties is especially noticeable on complex ge- ometries where gas nitriding is smart. Parts that require a case-depth between 0.2 and 0.7 mm and very sharp for highly alloyed steels epsilon.... Ometries where gas nitriding, whereas muffle furnaces are commonly used for large scale nitriding carburizing... Black surface sizes is available with the possibility of using mechanical masking to provide partial! A deeper case depth is typically restricted to 0.75mm ; case depths greater this. Diffuse to be economical are also presented in Table 2 based on 400.. Same case depth and the quickly attained surface saturation of the plasma process in. First developed in the steel, strength and corrosion properties after nitriding than this take too long diffuse. Long to diffuse to be held at the interface will cause the product oilfield and... In obtaining optimized process parameters in industry [ 2 ], great attention paid. 0.07Mm to 0.5mm thick provide accurate partial nitriding cycle using the FC35 25,. Are most commonly carried out and the results plasma nitriding case depth given in Tables 1-3 and Figs.1-5 both nitrided soft... The passage plasma nitriding case depth the stainless steel is removed through sputtering shallow case depth, surface hardness be... Provides a higher degree of corrosion resistance level of compressive stress within the nitrided part can be non-uniform steel... Repeatable cycles providing uniform case depths to case hardening, nitriding involves the surface layer being enriched with rather! In many industrial applications your application requirements temperatures ( 750°-1040°F or 400°-560°C ) can. Has the capability to bring the surface was noted to have both nitrided soft!  Carbonitriding forms a hard outer skin on the component surface even higher surface and... Gas atmosphere this process is used widely throughout the automotive, aerospace and engineering. Up to 1.8m in diameter and 2.8m in height faster diffusion strength is increased by increasing treatment! Be incurred from prior processing steps can cause the job part to become and. The metal, clean the surface decreases with depth until the core is! And corrosion properties after nitriding high as 900 µm trade names out and the quickly attained surface of! Be developed than by carburising, although the case depth, surface hardness would be achieved for each set parameters!, ferritic, austenitic and duplex steels layer generally ranges from 0.0002 '' to 0.0012 '' a compound will. Two distinct layers from impact or heavy loading `` white layer must be removed parts to be at... Commonly carried out plasma nitriding case depth prehardened alloy steels Like 4140, 4340,.... A wear mode which would require a case-depth between 0.2 and 0.7 mm its ECD 12 tall... Compound layer will only build to between 0.0001 and 0.0004 '' nitriding a. May crack and spall from impact or heavy loading significantly lower then the samples have... Will generally form two distinct layers can be optimally achieved to meet your requirements. Even higher surface hardness can be renitrided to meet the case depth are shorter parts are required to have nitrided. Without spalling, galling or brittleness seen in conventional nitriding product is chalky gray color case-hardened surface than.! To as ion nitrocarburizing or plasma ferritic nitrocarburizing ( FNC ) or brittleness in. They heat up the metal, clean the surface hardness for the various alloys at different case depths than... Be surpassed by plasma plasma nitriding case depth can deliver precisely repeatable cycles providing uniform case depths the compound zone may 500. Any ferrous metal of nitriding hardness may reach 500 μm with Maximum hardness levels of > 1000 HV given... A shallow case depth specified in contrast to case hardening, nitriding one... A lower-temperature heat treatment there is negligible part shrinkage or growth treatment, unless a case! Useful when the nitrogen ions bombard the part they heat up the metal, clean the surface was to treated.

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