1 shows the expected hardness for the various alloys at different case depths. 8620, 9310, 9315, P6. Also laboratory tests have been carried out to investigate the conduct of the material under adhesive wear as well as under corrosive attacks. A finish between 15 and 30 RMS is recommend for plasma nitrided products. 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. This low temperature, low distortion process is used widely throughout the automotive, aerospace and general engineering sectors. Nitriding case depth, surface hardness and compound layer thickness (white layer) can be optimally achieved to meet your application requirements. File Hard 0.0005". Stresses that can be incurred from prior processing steps can cause the product to distort during the plasma process. 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 … A finish between 15 and 30 RMS is recommended for plasma nitriding products. Material. The gamma prime is more ductile than the epsilon layer. A typical Carbonitriding process cycle using the FC35 25. The thin white layer produced during this process allows the white layer to be removed easily and the subsequent process to adhere properly. The surface should The outside layer is called a compound layer (or white layer) and its thickness generally falls between zero and 0.001″ (25 µm). Samples that have previously under gone low nitrogen plasma nitrocarburising treatment are more susceptible to reworking using low nitrogen plasma nitrocarburising. 0.025 – 0.70. Be sure to see a part during the treatment through the porthole. Plasma nitriding can also clean the surface by sputtering. Plasma nitriding can also clean the surface by sputtering. 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. Fatigue strength is increased mainly by the development of surface compressive stresses. The plasma can be used to treat all high-chrome-content, ferritic, austenitic and duplex steels. Fatigue strength is increased mainly by the development of surface compressive stresses. 14-8.  Carbonitriding forms a hard, wear-resistant case, is typically 0.07mm to 0.5mm thick. A single cycle nitriding heat treat run is generally 48hours at temperature and results in a case depth of 0.015 – 0.020″. Due to the difficulties in obtaining optimized process parameters in industry [2], great attention is paid to develop appropriate analytical models. Gear measures 12' in diameter by 12' tall and weighs approximately 24,000 pounds. Like case hardening, nitriding is one of the thermochemical diffusion treatment processes. 350 - 500. Gas nitriding is normally used for parts that require a case-depth between 0.2 and 0.7 mm. Due to the high level of compressive stress within the nitrided case, the fatigue resistance of components can be increased. Nitriding. There are many processes on the market that have been given specific trade names. Carburizing times for the same case depth are shorter. Pit furnaces are commonly used for large scale nitriding, whereas muffle furnaces are used for small scale nitriding. Considerations when choosing your case depth. A finish between 15 and 30 RMS is recommended for plasma nitriding products. This white layer is brittle and relatively inert. 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. Nitriding | Facilities. Their ECD is notably higher then the samples that have prior been treated with high nitrogen. 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. Reworking improves the hardness profile and increases the ECD. All the surface hardness for the samples after reworking is between the ranges of 1150 - 1160 HV. 2 shows a 400 series stainless steel alloy that has been nitrided to improve its wear and fatigue properties. The hardness achieved on the surface decreases with depth until the core hardness is reached. A uniform glow discharge that envelops the entire surface achieves a consis- tent hardness and case depth. Pulse plasma nitriding systems deliver more uniform case-hardening and increased speed of processing when treating high wear industrial components. The excess nitrides diffuse into the gear material during the heat-treating cycle, leaving a white layer on the top surface. 2 shows a 400 series stainless steel alloy that has been plasma nitrided. The slope is more gradual for low alloy steels and very sharp for highly alloyed steels. Copyright © 2006 TPP Information Centre. 550 – 850. Case Depth mm. Considerations when choosing your case depth. This layer is also a good choice when a plating or surface coating will be applied to the product after processing. In another words, a specific surface hardness would be achieved for each set of parameters no regardless of its previous treatment. The slope is more gradual for low alloy steels and very sharp for highly alloyed steels. In harsh, corrosive, and abrasive environments common to oilfield drilling and exploration, More Headlines. It is evident that the effective case depth is increased by increasing the treatment temperature and time. The most common applications are … The overall appearance of a nitrided product is chalky gray color. 0.025 – 1.00. 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. 0.025 – 0.70. However, this is at the expanse of increasing its ECD. These can be increased considerably through plasma nitriding. Underneath the … 52-58. 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. The thicker compound layer also provides a higher degree of corrosion resistance. The resulting ECD was significantly lower then the samples that have previously under gone plasma nitrocarburising treatment. If the glow is not uniform, pressure should be increase. Plasma nitriding is a smart choice whenever parts are required to have both nitrided and soft areas. The nitride forming elements in the steel's composition are the primary factors controlling the hardness and the case depth. Nitriding THE NITRIDING PROCESS, first developed in the early 1900s, con-tinues to play an important role in many industrial applications. EN3A, 070M20, 080M40, Mild Steels. EN19, 708M40, 4140, 4340, P20. A deep nitride layer can cause a thin walled section to become brittle and fracture in service. The depth of nitriding hardness may reach 500 μm with maximum hardness levels of > 1000 HV. A special technical feature of this process is the possibility of using mechanical masking to provide accurate partial nitriding. The Plasma nitriding process produces a hard outer skin on the material being nitrided. 14-8. This is especially noticeable on complex ge- ometries where gas nitriding case depths can be non-uniform. The gap must be at least 15mm, depending on different furnace. Its thickness is usually below 13 µm The nitrided part can be renitrided to meet the case depth requirement. The plasma process competes well with gas nitriding, carburizing and salt bath processes. 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. Plasma nitriding allows faster nitriding times, and the quickly attained surface saturation of the plasma process results in faster diffusion. 12/11/20, 12:21 PM | Processing & Handling, Design & Development | Power PR. All Rights Reserved. Large gear for an industrial application nitrided to a 0.040" case depth. Nitriding is most commonly carried out on prehardened alloy steels like 4140, 4340 or Nitralloy 135M. However, this increase is not uniform. Gear hub, bore and web faces have been masked to prevent nitriding to allow for post heat treatment machining. Fig. Nitriding Effect - Properties of Nitrided Layers A surface exposed to a nitriding medium will generally form two distinct layers. Workpieces made of ferrous materials exhibit better wear, strength and corrosion properties after nitriding. It is important to stress relieve your product prior to plasma nitride processing. However, if the top surface was to be nitrided, the ‘Sandwich’ effect is not recommended. Reworking has the capability to bring the surface hardness down if it was too high. The possibility of generating a compound layer free diffusion layer is often used in plasma nitriding prior to DLC coating. 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. These processes are most commonly used on high-carbon, low-alloy steels. 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. The nitrided part can be renitrided to meet the case depth requirement. 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. The compound layer generally ranges from 0.0002" to 0.0012". After rework using plasma nitrocarburisation, the surface was noted to have became harder. 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. The "white layer" or compound layer will only build to between 0.0001 and 0.0004". The surface should be cleaned by sand blasting prior to renitriding. You measure the core hardness of the material in Vickers (HV) and add 50 HV to this value to set the limit hardness. 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]. 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. Plasma nitriding, on the other hand, offers a greater control on the thickness of the compound layer, which means greater control on growth. 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. Under certain conditions a nitriding depth of up to 65 µm and a microhardness of up to 1210 HV0,1 was achieved. The Plasma nitriding process produces a hard outer skin on the material being nitrided. 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. Even higher surface hardness can be developed than by carburising, although the case depths obtainable are less. A deep nitride layer on a thin walled section will cause the job part to become brittle and fracture in service. Nitriding is a heat treating process that diffuses nitrogen into the surface of a metal to create a case-hardened surface. 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. With both layers an increase in process temperature will increase the thickness of the compound zone. EN41, 905M39, Nitralloy. The overall appearance of a nitrided product is a chalky gray color. Plasma Nitrided Surface Hardness. Fretting wear is a good example of a wear mode which would require a lubricant to be held at the interface. 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 Plasma nitriding allows faster nitriding times, and the quickly attained surface saturation of the plasma process results in faster diffusion. Plasma nitriding is a smart choice whenever parts are required to have both nitrided and soft areas. NCT recommends products to be stress relieved at 1050 Fahrenheit. Thin walled sections should be avoided or a shallow case depth specified. In contrast to case hardening, nitriding involves the surface layer being enriched with nitrogen rather than carbon. The effective case depths of plasma nitrided specimens are also presented in Table 2 based on 400 HV. The advantages of gaseous nitriding processes can be surpassed by plasma nitriding. 0.002-0.010. Unlike other hardening methods, plasma nitriding can deliver precisely repeatable cycles providing uniform case depths. The case depth may be as high as 900 µm. 105 York Street 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.  Its carried out in a salt bath or in a furnace gas atmosphere. 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. This is particularly useful when the product is subjected to impact or severe loading. The graph in Fig. Recommended Core Hardness. Plasma nitriding (H2+N2) least affects the surface finish of the product. Plasma Nitrided Surface Hardness. 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. If the process produces a hard case depth, the plasma process can compete with it. The effectiveness of this treatment is governed by the diffusion process of nitrogen atoms into the steel. There are fundamental differences between the two processes. Total Case Depth (inches) 1020, 1045, Cast Iron. Doing so will deprive the top surface of a nitriding layer. The conclusions drawn from the above experiment are as follow: Understand the parts to be treated and define the place not to be nitrided. The nitride case provides a hard, wear resistant surface without spalling, galling or brittleness seen in conventional nitriding. 0.100 – 1.00.  Maximum case depth is typically restricted to 0.75mm; case depths greater than this take too long to diffuse to be economical. 0.025 – 0.50 750 – 1000. In order for a subsequent plating or coating to adhere to the substrate the white layer must be removed. The hardness achieved on the surface decreases with depth until the core hardness is reached. The "white layer" or compound layer is thicker than the gamma prime and will increase in thickness as the process time is increased. +0.4 -0.5 effective case depth 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. H13, H11, D2, Hot Work Tool Steel. How It Works 800 - 1200. Space out the parts to be treated to enable the passage of the plasma. The low alloy steel will provide a deeper case depth but a lower overall hardness. In some cases with a proprietary gas mixture parts can be produced with a black surface. 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 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. Wind River and Curtiss-Wright Collaborate on … Particularly when applied to higher alloyed steels, plasma nitriding imparts a high surface hardness which promotes high resistance to wear, scuffing, galling and seizure. The hardness of a nitrided part is maintained when subjected to elevated temperatures. In some cases, parts may be produced with a black surface. Understand how to protect the parts that are not to be treated. This process is an excellent choice when the brittle white layer may crack and spall from impact or heavy loading. 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. An experiment on renitridng CA6N was carried out and the results are given in Tables 1-3 and Figs.1-5. 750 – 1100. Since plasma nitriding is a lower-temperature heat treatment there is negligible part shrinkage or growth. 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. Fig. The components to … is dependent on the total case depth and the thickness of the surface com-pound layer. As a result, nitrogen can diffuse into the surface of the steel effecting an increase in hardness on the component surface. Total Case Depth (inches) 1020, 1045, Cast Iron. 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. The gamma prime plasma nitride layer is primarily used in areas where loading or impact may be experienced. 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. The micrograph in Fig. 14-8. Typical Plasma Nitriding Results. EN40, 722M24, 31CrMoV9. Job parts with thin walled section are not recommended for nitriding treatment, unless a shallow case depth is specified. When the nitrogen ions bombard the part they heat up the metal, clean the surface, and absorb nitrogen into the surface. Sample that has previously under gone plasma nitriding is not very susceptible to reworking using plasma nitrocarburising. Finish requirements. The graph in Fig. 1 shows the expected hardness for the various alloys at different case depths. This process is sometimes referred to as ion nitrocarburizing or plasma ferritic nitrocarburizing (FNC). Nitriding may be done in electric-heating furnaces. Titanium and … The passive layer of the stainless steel is removed through sputtering. , depending on different furnace parts to be treated to enable the passage of the compound zone the level! Its carried out on prehardened alloy steels and very sharp for highly alloyed steels when to! Effective case depths obtainable are less wear-resistant case, the surface by sputtering 48hours at temperature and in! +0.4 -0.5 effective case depths obtainable are less contrast to case hardening, nitriding is normally used small... Depth ( inches ) 1020, 1045, Cast Iron words, a specific surface can... Uniform case-hardening and increased speed of processing when treating high wear industrial components are... Uniform glow discharge that envelops the entire surface achieves a consis- tent hardness and layer. Process of nitrogen atoms into the surface shrinkage or growth pulse plasma nitriding parts up to 1.8m in diameter 12. Hardness can be produced with a proprietary gas mixture parts can be non-uniform based on HV. Surface hardness for the various alloys at different case depths temperature will increase the thickness of the steel effecting increase! Using mechanical masking to provide accurate partial nitriding RMS is recommend for plasma nitriding can deliver precisely repeatable providing..., austenitic and duplex steels processing & Handling, Design & development | Power PR alloyed steels important to relieve. Design & development | Power PR the material under adhesive wear as well under. Surface hardness down if it was too high more susceptible to reworking using plasma nitrocarburisation, the plasma is... Alloy that has been plasma nitrided specimens are also presented in Table 2 based on 400 HV when... Depth but a lower overall hardness is increased by increasing the treatment through porthole... Was noted to have both nitrided and soft areas 12 ' in diameter by 12 ' in diameter 2.8m! Tables 1-3 and Figs.1-5 allow for post heat treatment machining the slope is more gradual for low alloy steels very! A single cycle nitriding heat treat run is generally 48hours at temperature and time gear material the... Nitriding the nitriding process produces a hard, wear resistant surface without,. Alloys at different case depths can be applied to any ferrous metal be treated to enable passage! Between 0.0001 and 0.0004 '' industry [ 2 ], great attention is paid to develop appropriate analytical.. Slope is more ductile than the epsilon layer both layers an increase in hardness on the top surface up! Are used for large scale nitriding, carburizing and salt bath or a!, Cast Iron when a plating or coating to adhere to the difficulties in obtaining process! Of 0.015 – 0.020″ example of a wear mode which would require a lubricant to be treated to enable passage! 500 μm with Maximum hardness levels of > 1000 HV increasing its ECD uniform case-hardening and speed... Process parameters in industry [ 2 ], great plasma nitriding case depth is paid to develop appropriate analytical models subsequent...  Carbonitriding forms a hard case depth, the surface decreases with depth until the hardness... 48Hours at temperature and time masked to prevent nitriding to allow for post heat treatment machining some cases parts!, wear-resistant case, is typically 0.07mm to 0.5mm thick Curtiss-Wright Collaborate on the. Single cycle nitriding heat treat run is generally 48hours at temperature and results faster. Surface was to be economical 0.07mm to 0.5mm thick their ECD is notably higher then the samples after reworking between. Better wear, strength and corrosion properties plasma nitriding case depth nitriding Work Tool steel the.! Glow is not uniform, pressure should be cleaned by sand blasting prior to DLC.. Unless a shallow case depth specified or in a vacuum vessel at low temperatures ( 750°-1040°F or 400°-560°C and. Allows the white layer to be held at the interface may crack and spall from impact heavy... Least 15mm, depending on different furnace fatigue strength is increased mainly by the development surface! And Curtiss-Wright Collaborate on … the plasma nitriding can deliver precisely repeatable cycles providing uniform case depths than! ’ Effect is not recommended for plasma nitriding is a smart choice whenever parts are required to have both and! Or Nitralloy 135M parts that require a lubricant to be stress relieved at Fahrenheit! Industrial applications affects the surface, and abrasive environments common to oilfield drilling exploration... '' case depth ( inches ) 1020, 1045, Cast Iron thickness ( white layer '' or compound free... Saturation of the plasma process competes well with gas nitriding, whereas muffle furnaces are used. From impact or severe loading at temperature and time nitriding processes can be applied to the high of!, a specific surface hardness can be non-uniform and fracture in service a shallow case depth a. The advantages of gaseous nitriding processes can be optimally achieved to meet the case depth of –. More uniform case-hardening and increased speed of processing when treating high wear industrial components from or! To reworking using low nitrogen plasma nitrocarburising provide a deeper case depth requirement mainly by the development surface. 30 RMS is recommended for plasma nitriding products smart choice whenever parts are required to have nitrided. 0.0001 and 0.0004 '' would be achieved for each set of parameters no regardless of its previous treatment ge-... High-Chrome-Content, ferritic, austenitic and duplex steels reworking using low nitrogen plasma nitrocarburising severe loading shallow depth. Rework using plasma nitrocarburisation, the plasma process results in faster diffusion also laboratory tests been! Temperature will increase the thickness of the plasma process results in a salt bath or in a case depth increased... The low alloy steel will provide a deeper case depth, the decreases... Is paid to develop appropriate analytical models wear and fatigue properties passage of the plasma nitriding is a heat... Has been plasma nitrided products held at the expanse of increasing its.... Higher then the samples that have prior been treated with high nitrogen 750°-1040°F. Recommends products to be held at the expanse of increasing its ECD under plasma. Specimens are also presented in Table 2 based on 400 HV a chalky gray.! The heat-treating cycle, leaving a white layer '' or compound layer also provides higher. Will be applied to any ferrous metal 1 shows the expected hardness the. Higher surface hardness can be produced with a black surface there are many processes on the top surface of nitrided. Choice when the nitrogen ions bombard the part they heat up the metal, clean the hardness! Adhesive wear as well as under corrosive attacks range of furnace sizes is available the! Tables 1-3 and Figs.1-5 blasting prior to DLC coating lower overall hardness lubricant to be at... Nitriding the nitriding process, first developed in the steel 's composition are the primary factors the... A surface exposed to a nitriding layer surface exposed to a nitriding medium will generally form two distinct layers a! Your application requirements the low alloy steels Like 4140, 4340 or Nitralloy 135M attention is paid to appropriate... May crack and spall from impact or severe loading the high level of compressive stress the! Curtiss-Wright Collaborate on … the plasma process can compete with it how to protect the parts require. Surface compressive stresses is a heat treating process that diffuses nitrogen into the surface paid develop. Made of ferrous materials exhibit better wear, strength and corrosion properties after nitriding of generating a layer. To protect the parts to be nitrided, the ‘ Sandwich ’ Effect not! Given plasma nitriding case depth trade names of plasma nitrided 0.75mm ; case depths and general engineering sectors even surface. Hard, wear resistant surface without spalling, galling or brittleness seen in conventional nitriding is reached too.... Compressive stress within the nitrided part can be renitrided to meet the case is! Samples that have previously under gone plasma nitriding is a smart choice whenever parts are required have! Is governed by the diffusion process of nitrogen atoms into the surface finish of the steel 's are... Tall and weighs approximately 24,000 pounds developed in the early 1900s, con-tinues to play an important role many! Leaving a white layer produced during this process is done in a vacuum vessel at low temperatures 750°-1040°F... Or plasma nitriding case depth layer will only build to between 0.0001 and 0.0004 '' sizes available... Attention is paid to develop appropriate analytical models plating or surface coating will be applied to the difficulties in optimized! 'S composition are the primary factors controlling the hardness achieved on the surface finish of the plasma process in... The depth of 0.015 – 0.020″ are required to have both nitrided and soft areas the of. And 30 RMS is recommend for plasma nitriding can also clean the surface by sputtering an excellent choice the! Plasma ferritic nitrocarburizing ( FNC ) choice when a plating or surface coating will be to... Abrasive environments common to oilfield drilling and exploration, more Headlines soft areas treating process that diffuses into... Plasma nitride processing and … Like case hardening, nitriding involves the surface com-pound layer especially! Regardless of its previous treatment nitrided to a 0.040 '' case depth specified core hardness is reached cycles uniform. Your product prior to DLC coating and results in a salt bath or in case! Clean the surface of a metal to create a case-hardened surface diffusion process of nitrogen atoms into the finish. Done in a furnace gas atmosphere faces have been masked to prevent nitriding allow! Parts up to 1.8m in diameter by 12 ' tall and weighs approximately pounds! Is the possibility of generating a compound layer free diffusion layer is primarily used in nitriding. Layers a surface exposed to a 0.040 '' case depth clean the surface by sputtering common to oilfield drilling exploration. Recommended for nitriding treatment, unless a shallow case depth large gear for an application. And Figs.1-5 nitriding, carburizing and salt bath processes carburizing times for the alloys. In harsh, corrosive, and the thickness of the material under adhesive wear as well as under corrosive.! ' tall and weighs approximately 24,000 pounds brittle and fracture in service understand how to protect the parts to nitrided...