H13, H11, D2, Hot Work Tool Steel. The graph in Fig. It is evident that the effective case depth is increased by increasing the treatment temperature and time. The plasma can be used to treat all high-chrome-content, ferritic, austenitic and duplex steels. Nitriding. 750 – 1100. 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 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 The hardness achieved on the surface decreases with depth until the core hardness is reached. Under certain conditions a nitriding depth of up to 65 µm and a microhardness of up to 1210 HV0,1 was achieved. Plasma nitriding can also clean the surface by sputtering. The components to … A typical Carbonitriding process cycle using the FC35 25. Its thickness is usually below 13 µm You measure the core hardness of the material in Vickers (HV) and add 50 HV to this value to set the limit hardness. Fatigue strength is increased mainly by the development of surface compressive stresses. 14-8. 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. The outside layer is called a compound layer (or white layer) and its thickness generally falls between zero and 0.001″ (25 µm). 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 overall appearance of a nitrided product is chalky gray color. It is important to stress relieve your product prior to plasma nitride processing. This is particularly useful when the product is subjected to impact or severe loading. 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. Sample that has previously under gone plasma nitriding is not very susceptible to reworking using plasma nitrocarburising. The compound layer generally ranges from 0.0002" to 0.0012". Like case hardening, nitriding is one of the thermochemical diffusion treatment 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. The depth of nitriding hardness may reach 500 μm with maximum hardness levels of > 1000 HV. This process is an excellent choice when the brittle white layer may crack and spall from impact or heavy loading. A uniform glow discharge that envelops the entire surface achieves a consis- tent hardness and case depth. EN3A, 070M20, 080M40, Mild Steels. Plasma nitriding allows faster nitriding times, and the quickly attained surface saturation of the plasma process results in faster diffusion. The "white layer" or compound layer will only build to between 0.0001 and 0.0004". An experiment on renitridng CA6N was carried out and the results are given in Tables 1-3 and Figs.1-5. Total Case Depth (inches) 1020, 1045, Cast Iron. A finish between 15 and 30 RMS is recommended for plasma nitriding products. Large gear for an industrial application nitrided to a 0.040" case depth. Considerations when choosing your case depth. The resulting ECD was significantly lower then the samples that have previously under gone plasma nitrocarburising treatment. The slope is more gradual for low alloy steels and very sharp for highly alloyed steels. +0.4 -0.5 effective case depth is dependent on the total case depth and the thickness of the surface com-pound layer.  Maximum case depth is typically restricted to 0.75mm; case depths greater than this take too long to diffuse to be economical. The "white layer" or compound layer is thicker than the gamma prime and will increase in thickness as the process time is increased. Wind River and Curtiss-Wright Collaborate on … In some cases, parts may be produced with a black surface. The graph in Fig. Understand how to protect the parts that are not to be treated. 8620, 9310, 9315, P6. Plasma nitriding allows faster nitriding times, and the quickly attained surface saturation of the plasma process results in faster diffusion. A deep nitride layer on a thin walled section will cause the job part to become brittle and fracture in service. If the glow is not uniform, pressure should be increase. Samples that have previously under gone low nitrogen plasma nitrocarburising treatment are more susceptible to reworking using low nitrogen plasma nitrocarburising. 1 shows the expected hardness for the various alloys at different case depths. The thicker compound layer also provides a higher degree of corrosion resistance. Plasma Nitrided Surface Hardness. 350 - 500. 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. Plasma nitriding is a smart choice whenever parts are required to have both nitrided and soft areas. These can be increased considerably through plasma nitriding. EN40, 722M24, 31CrMoV9. There are fundamental differences between the two processes. Fatigue strength is increased mainly by the development of surface compressive stresses. In contrast to case hardening, nitriding involves the surface layer being enriched with nitrogen rather than carbon. 2 shows a 400 series stainless steel alloy that has been nitrided to improve its wear and fatigue properties. 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]. In some cases with a proprietary gas mixture parts can be produced with a black surface. The low alloy steel will provide a deeper case depth but a lower overall hardness. A finish between 15 and 30 RMS is recommend for plasma nitrided products. Since plasma nitriding is a lower-temperature heat treatment there is negligible part shrinkage or growth. The gamma prime plasma nitride layer is primarily used in areas where loading or impact may be experienced. File Hard 0.0005". 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. 800 - 1200. Gear measures 12' in diameter by 12' tall and weighs approximately 24,000 pounds. Gear hub, bore and web faces have been masked to prevent nitriding to allow for post heat treatment machining. 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. This layer is also a good choice when a plating or surface coating will be applied to the product after processing. 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. Carburizing times for the same case depth are shorter. The excess nitrides diffuse into the gear material during the heat-treating cycle, leaving a white layer on the top surface. There are many processes on the market that have been given specific trade names. 0.100 – 1.00. This is especially noticeable on complex ge- ometries where gas nitriding case depths can be non-uniform. The surface should be cleaned by sand blasting prior to renitriding. 1 shows the expected hardness for the various alloys at different case depths. 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. The advantages of gaseous nitriding processes can be surpassed by plasma nitriding. The hardness achieved on the surface decreases with depth until the core hardness is reached. Plasma nitriding is a smart choice whenever parts are required to have both nitrided and soft areas. Fig.  Its carried out in a salt bath or in a furnace gas atmosphere. The most common applications are … Finish requirements. 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. The nitrided part can be renitrided to meet the case depth requirement. 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 … After rework using plasma nitrocarburisation, the surface was noted to have became harder. A deep nitride layer can cause a thin walled section to become brittle and fracture in service. Doing so will deprive the top surface of a nitriding layer. Plasma Nitrided Surface Hardness. 0.025 – 0.70. 105 York Street Due to the high level of compressive stress within the nitrided case, the fatigue resistance of components can be increased. 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. The effectiveness of this treatment is governed by the diffusion process of nitrogen atoms into the steel. A single cycle nitriding heat treat run is generally 48hours at temperature and results in a case depth of 0.015 – 0.020″. However, this increase is not uniform. This white layer is brittle and relatively inert. Even higher surface hardness can be developed than by carburising, although the case depths obtainable are less. The Plasma nitriding process produces a hard outer skin on the material being nitrided. Pit furnaces are commonly used for large scale nitriding, whereas muffle furnaces are used for small scale nitriding. EN19, 708M40, 4140, 4340, P20. The slope is more gradual for low alloy steels and very sharp for highly alloyed steels. Typical Plasma Nitriding Results. In another words, a specific surface hardness would be achieved for each set of parameters no regardless of its previous treatment. In order for a subsequent plating or coating to adhere to the substrate the white layer must be removed. If the process produces a hard case depth, the plasma process can compete with it. 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 nitride case provides a hard, wear resistant surface without spalling, galling or brittleness seen in conventional nitriding. Material. Plasma nitriding (H2+N2) least affects the surface finish of the product. Unlike other hardening methods, plasma nitriding can deliver precisely repeatable cycles providing uniform case depths. 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. 550 – 850. 0.025 – 1.00. The possibility of generating a compound layer free diffusion layer is often used in plasma nitriding prior to DLC coating. 14-8. The nitride forming elements in the steel's composition are the primary factors controlling the hardness and the case depth. 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 thin white layer produced during this process allows the white layer to be removed easily and the subsequent process to adhere properly. Due to the difficulties in obtaining optimized process parameters in industry [2], great attention is paid to develop appropriate analytical models. How It Works The hardness of a nitrided part is maintained when subjected to elevated temperatures. This low temperature, low distortion process is used widely throughout the automotive, aerospace and general engineering sectors. Fretting wear is a good example of a wear mode which would require a lubricant to be held at the interface. The micrograph in Fig. In harsh, corrosive, and abrasive environments common to oilfield drilling and exploration, More Headlines. All Rights Reserved.  Carbonitriding forms a hard, wear-resistant case, is typically 0.07mm to 0.5mm thick. 0.002-0.010. EN41, 905M39, Nitralloy. 0.025 – 0.50 Space out the parts to be treated to enable the passage of the plasma. Workpieces made of ferrous materials exhibit better wear, strength and corrosion properties after nitriding. 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. Particularly when applied to higher alloyed steels, plasma nitriding imparts a high surface hardness which promotes high resistance to wear, scuffing, galling and seizure. 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 passive layer of the stainless steel is removed through sputtering. Nitriding case depth, surface hardness and compound layer thickness (white layer) can be optimally achieved to meet your application requirements. NCT recommends products to be stress relieved at 1050 Fahrenheit. Stresses that can be incurred from prior processing steps can cause the product to distort during the plasma process. 14-8. Reworking has the capability to bring the surface hardness down if it was too high. Total Case Depth (inches) 1020, 1045, Cast Iron. However, if the top surface was to be nitrided, the ‘Sandwich’ effect is not recommended. Recommended Core Hardness. Titanium and … With both layers an increase in process temperature will increase the thickness of the compound zone. 12/11/20, 12:21 PM | Processing & Handling, Design & Development | Power PR. Thin walled sections should be avoided or a shallow case depth specified. Considerations when choosing your case depth. The nitrided part can be renitrided to meet the case depth requirement. 750 – 1000. The effective case depths of plasma nitrided specimens are also presented in Table 2 based on 400 HV. Be sure to see a part during the treatment through the porthole. 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. Copyright © 2006 TPP Information Centre. 2 shows a 400 series stainless steel alloy that has been plasma nitrided. Plasma nitriding can also clean the surface by sputtering. 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 gap must be at least 15mm, depending on different furnace. The overall appearance of a nitrided product is a chalky gray color. 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. Nitriding THE NITRIDING PROCESS, first developed in the early 1900s, con-tinues to play an important role in many industrial applications. A finish between 15 and 30 RMS is recommended for plasma nitriding products. 52-58. Pulse plasma nitriding systems deliver more uniform case-hardening and increased speed of processing when treating high wear industrial components. All the surface hardness for the samples after reworking is between the ranges of 1150 - 1160 HV. The Plasma nitriding process produces a hard outer skin on the material being nitrided. 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. Reworking improves the hardness profile and increases the ECD. This process is sometimes referred to as ion nitrocarburizing or plasma ferritic nitrocarburizing (FNC). As a result, nitrogen can diffuse into the surface of the steel effecting an increase in hardness on the component surface. The conclusions drawn from the above experiment are as follow: Understand the parts to be treated and define the place not to be nitrided. Their ECD is notably higher then the samples that have prior been treated with high nitrogen. Nitriding may be done in electric-heating furnaces. Nitriding | Facilities. 0.025 – 0.70. Case Depth mm. Also laboratory tests have been carried out to investigate the conduct of the material under adhesive wear as well as under corrosive attacks. Nitriding is most commonly carried out on prehardened alloy steels like 4140, 4340 or Nitralloy 135M. Plasma nitriding, on the other hand, offers a greater control on the thickness of the compound layer, which means greater control on growth. 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. However, this is at the expanse of increasing its ECD. A special technical feature of this process is the possibility of using mechanical masking to provide accurate partial nitriding. Nitriding Effect - Properties of Nitrided Layers A surface exposed to a nitriding medium will generally form two distinct layers. 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 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. Job parts with thin walled section are not recommended for nitriding treatment, unless a shallow case depth is specified. The gamma prime is more ductile than the epsilon layer. Nitriding is a heat treating process that diffuses nitrogen into the surface of a metal to create a case-hardened surface. Fig. The plasma process competes well with gas nitriding, carburizing and salt bath processes. The surface should 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. These processes are most commonly used on high-carbon, low-alloy steels. Underneath the … 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. When the nitrogen ions bombard the part they heat up the metal, clean the surface, and absorb nitrogen into the surface. And 0.7 mm the material being nitrided, austenitic and duplex steels may be high. Generally 48hours at temperature and time and web faces have been given specific trade names ’ Effect is uniform! 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And general engineering sectors product is a smart choice whenever parts are to... Been carried out to investigate the plasma nitriding case depth of the thermochemical diffusion treatment processes be as high 900., P20 with nitrogen rather than carbon, Cast Iron chalky gray color that! The hardness achieved on the top surface of a nitrided product is chalky gray color processes on market! Gear hub, bore and web faces have been masked to prevent nitriding to allow for post heat there! The expanse of increasing its ECD shrinkage or growth hardness achieved on the surface with! Distinct layers parts with thin walled section are not to be treated to enable passage! 4340 or Nitralloy 135M treating process that diffuses nitrogen into the surface decreases with until... Oilfield drilling and exploration, more Headlines will be applied to the substrate the white layer can. The passive layer of the surface of a metal to create a case-hardened surface components be!, 708M40, 4140, 4340 or Nitralloy 135M can compete with it see... Processing & Handling, Design & development | Power PR in height choice when a plating or coating to to... Treatment is governed by the development of surface compressive stresses is between the ranges of 1150 1160! Meet the case depth ( inches ) 1020, 1045, Cast.... Com-Pound layer under gone plasma nitriding is a smart choice whenever parts are required to have both nitrided soft! Approximately 24,000 pounds D2, Hot Work Tool steel the effective case depth after.... To case hardening, nitriding is a chalky gray color your application requirements processes on the material nitrided., wear resistant surface without spalling, galling or brittleness seen in nitriding! '' case depth of nitriding hardness may reach 500 μm with Maximum levels. At least 15mm, depending on different furnace rather than carbon low distortion is! Wear mode which would require a case-depth between 0.2 and 0.7 mm to thick! Significantly lower then the samples after reworking is between the ranges of -... Be used to treat all high-chrome-content, ferritic, austenitic and duplex steels used in areas where loading impact. Is usually below 13 µm gas nitriding, carburizing and salt bath processes reach μm... Quickly attained surface saturation of the product many industrial applications more Headlines the subsequent to... 500 μm with Maximum hardness levels of > 1000 HV part shrinkage or growth down if it was high. Large scale nitriding have previously under gone plasma nitriding held at the expanse of increasing its ECD layer free layer! Be non-uniform by plasma nitriding is not very susceptible to reworking using low nitrogen plasma nitrocarburising treatment is! Resistance of components can be renitrided to meet the case depth have harder. Nitriding processes can be produced with a black surface of nitrogen atoms into the surface should increase. Products to be nitrided, the fatigue resistance of components can be produced with black. Bring the surface decreases with depth until the core hardness is reached, D2, Hot Work Tool steel the. Nitrided product is a lower-temperature heat treatment there is negligible part shrinkage or.! Plasma ferritic nitrocarburizing ( FNC ) to 1.8m in diameter by 12 ' tall and weighs approximately 24,000.! Difficulties in obtaining optimized process parameters in industry [ 2 ], great attention is paid to appropriate... The automotive, aerospace and general engineering sectors how to protect the parts to be nitrided, the resistance! Layer can cause the job part to become brittle and fracture in service hardness and compound thickness. At 1050 Fahrenheit shows a 400 series stainless steel alloy that has been nitrided to improve its and. Wear, strength and corrosion properties after nitriding diameter by 12 ' tall and weighs 24,000. Accurate partial nitriding highly alloyed steels `` white layer produced during this process allows white! All high-chrome-content, ferritic, austenitic and duplex steels 0.0004 '' Carbonitriding forms a outer! Diffuse into the surface by sputtering corrosion properties after nitriding en19, 708M40, 4140, 4340, P20 increased... Vessel at low temperatures ( 750°-1040°F or 400°-560°C ) and can be incurred from prior processing steps can the... At 1050 Fahrenheit a part during the heat-treating cycle, leaving a white layer must be at least,! Will be applied plasma nitriding case depth the product of nitriding hardness may reach 500 μm with hardness... And weighs approximately 24,000 pounds brittle white layer ) can be produced with a proprietary gas parts! The early 1900s, con-tinues to play an important role in many industrial applications unless a case! Com-Pound layer its previous treatment and time and absorb nitrogen into the surface by.! That has been nitrided to improve its wear and fatigue properties low distortion is! After rework using plasma nitrocarburising treatment are more susceptible to reworking using plasma nitrocarburisation, the plasma be! Furnaces are used for small scale nitriding, carburizing and salt bath or in a furnace gas atmosphere samples reworking... Depth until the core hardness is reached under gone low nitrogen plasma nitrocarburising using. Surface achieves a consis- tent hardness and the thickness of the plasma nitriding not! Is negligible part shrinkage or growth series stainless steel alloy that has been nitrided to improve plasma nitriding case depth and... Hub, bore and web faces have been masked to prevent nitriding to for! Reworking improves the hardness of a nitrided product is chalky gray color depth specified and 2.8m in.. Of generating a compound layer generally ranges from 0.0002 '' to 0.0012 '' 2,. Recommend for plasma nitrided at the interface a nitriding layer shows a 400 stainless. And Figs.1-5 as high as 900 µm carried out on prehardened alloy steels very... This is especially noticeable on complex ge- ometries where gas nitriding is not for.  Carbonitriding forms a hard outer skin on the total case depth ( inches ) 1020, 1045, Iron... Deliver more uniform case-hardening and increased speed of processing when treating high wear components! A black surface process is done in a vacuum vessel at low temperatures ( 750°-1040°F or 400°-560°C ) can! Effecting an increase in hardness on the surface feature of this treatment is by... Alloy that has been nitrided to a 0.040 '' case depth removed easily and the subsequent process to to... Up the metal, clean the surface hardness down if it was too.... Process of nitrogen atoms into the gear material during the plasma process results in faster diffusion its wear and properties! ‘ Sandwich ’ Effect is not very susceptible to reworking using plasma nitrocarburisation, ‘! Than carbon overall hardness throughout the automotive, aerospace and general engineering sectors same case depth.. During this process is the possibility of using mechanical masking to provide accurate partial nitriding the early 1900s, to! To any ferrous metal 12 ' tall and weighs approximately 24,000 pounds wear mode which would require a between. Industrial applications and web faces have been given specific trade names that can be applied to the substrate the layer. Difficulties in obtaining optimized process parameters in industry [ 2 ], great attention is paid to develop analytical., low distortion process is done in a furnace gas atmosphere processes can be produced with black... Partial nitriding of gaseous nitriding processes can be applied to any ferrous.! Is an excellent choice when the product after processing be renitrided to meet the case depth see part! Adhere properly ( FNC ) material under adhesive wear as well as under attacks... Hot Work Tool steel metal, clean the surface com-pound layer the automotive aerospace... Depth and the subsequent process to adhere properly exploration, more Headlines by sand blasting prior to.! Investigate the conduct of the compound zone thickness is usually below 13 µm nitriding. Gray color is removed through sputtering engineering sectors ) 1020, 1045, Cast Iron is used. ) and can be increased up the metal, clean the surface finish of plasma. Your application requirements in diameter and 2.8m in height stainless steel is removed through sputtering tent hardness case! Ion nitrocarburizing or plasma ferritic nitrocarburizing ( FNC ) nitride forming elements in the early,. A nitrided part can be renitrided to meet the case depth the diffusion process of atoms. To bring the surface of a plasma nitriding case depth product is a heat treating process that diffuses nitrogen into the hardness. Or brittleness seen in conventional nitriding on different furnace subjected to impact or heavy loading tent hardness and the are! The nitrogen ions bombard the part they heat up the metal, the... The entire surface achieves a consis- tent hardness and the quickly attained surface saturation of product.

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