Carburizing is a procedure that hardens metal surfaces while letting the metal underneath remain soft. Equation (8.7) is an approximate solution of the diffusion problem. 2010 - 2022 Miheu d.o.o. In this research, the effects of carburizing process and notch stress concentration on fatigue performance were analyzed by bending fatigue tests. In solid or pack carburizing is a process in which carbon monoxide derived from a solid compound decomposes at the metal surface into nascent carbon and carbon dioxide. Because the process is void of oxygen, it makes the oxidation of steel alloys a near impossibility. Prohibited Content 3. The result is a wear-resistant layer that makes carburizing an ideal process in the production of strong, safe metals. rev2023.3.3.43278. carburizing time calculationthe renaissance apartments chicago. Carburizing is a case hardening process in which carbon diffuses into the surface layer of a steel part at a temperature high enough to change the steel grain structure. Plasma carburization is increasingly used to improve the surface characteristics (such as wear, corrosion resistance, hardness, load-bearing capacity, in addition to quality-based variables) of various metals, notably stainless steels. Carburised steel, after diffusion step and quenching containing around 1%C. What's the difference between a power rail and a signal line? Both of these mechanisms strengthen the surface of the metal, the former by forming pearlite or martensite, and the latter via the formation of carbides. Connect and share knowledge within a single location that is structured and easy to search. Carburizing Case Depth Calculation Formula. After the diffusion period, parts are quenched inside itself and then, these are removed. Thermodynamic calculations. The right side of the equation (8.4) gives the hatched area of Fig. Regal Rexnord is an Equal Opportunity and Affirmative Action Employer. It's simple:steel which has been carburizedwill have a very hard exterior. This does not apply to gears as rate of cooling of gear tooth is greater than of a solid shaft. Visit Frank Beck Chevrolet to check out this new 2023 Chevrolet Silverado 1500 in person. This differential equation (8.8) has been solved to give carbon content as a function of time and distance as. this website, certain cookies have already been set, which you may delete and Putting the value of J from equation (8.3) to equation (8.4), and rearranging gives. Thus, the properties of core also form the basis of mechanical properties while designing heavy duty gears etc. There were six batch integral-quench atmosphere furnaces (two 2-zone and four single-zone), one pusher atmosphere carburizer line with related washers and tempering furnaces. scissors or swords). The increase in carbon content at the surface must be high enough to result in a martensitic layer with sufficient hardness, typically 700 HV, to provide a wear-resistant surface. Both of these mechanisms strengthen the surface of the metal, the former by forming pearlite or martensite, and the latter via the formation of carbides. Use MathJax to format equations. Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account. This work focuses on the effects of the carburizing temperature and time on the mechanical properties of mild steel carburized with activated carbon, at 850, 900 and 950 C, soaked at the carburizing temperature for 15 and 30 minutes, quenched in oil, tempered at 550 C and held for 60 minutes. absorption of carbon takes place at first rapidly at the surface of the steel because there is large difference between carbon potential of the atmosphere and the carbon content of the steel surface. [4], Typically the materials that are carbonized are low-carbon and alloy steels with initial carbon content ranging from 0.2 to 0.3%. This is done by exposing the part to a Carbon rich atmosphere at an elevated temperature and allows diffusion to transfer the Carbon atoms into steel. Using indicator constraint with two variables, Bulk update symbol size units from mm to map units in rule-based symbology, How to handle a hobby that makes income in US. Structure and Properties 3. Why are physically impossible and logically impossible concepts considered separate in terms of probability? This process uses gaseous hydrocarbons such as methane. (c) Coolants- Water quenching gives greater depths particularly in thick sections, (d) Grade of steel- More highly alloyed steel gives greater DC for thick parts. Gas-carburising often shows oxidation of grain boundaries to a depth of 0.025 mm from surface. It depends on the time and temperature of carburising, the carbon potential of the medium and the composition of the steel. snoopy happy dance emoji 8959 norma pl west hollywood ca 90069 8959 norma pl west hollywood ca 90069 Elements like Cr. Calculate the time necessary to increase the carbon content to 0.30 wt% at 0.030 in below the surface of the gear. Some uncarburized steel alloys provide natural surface hardness. Theory 5. If the carbon remains in solid solution, the steel is then heat treated to harden it. The carbon content of the surface is controlled by the activity of the carbon in the surrounding medium (called carbon potential of the atmosphere), or the maximum solubility of carbon in austenite at the carburising temperature, whichever is less, but the depth of penetration of carbon is dependent on the temperature and time of the carburising (Fig. The main advantage of using higher carburising temperatures is to increase the absorption and the diffusion rates to reduce the carburising times. It ionises the carburising gas and very rapidly carbon equivalent to solubility limit in austenite at that carburising temperature is adsorbed at the surface of the component. Temperatures are typically 790 to 845 C for times of 2 to 36 hours. The depth of carburising as a function of time can be evaluated by using Ficks laws of diffusion for semi-infinite case of infinite source. This allows for high heats to be injected into the contained atmosphere, greatly expediting the carburization process. The diffusion coefficient for carbon in iron at this temperature is: 9 x10-8 cm2/s. A Full Guide, What is Corrosion? Carburising Furnaces. Although it is the fastest carburizing process, it is only suitable for small batch sizes. Show transcribed image text Expert Answer 100% (6 ratings) Transcribed image text: This is displayed in Figure 1. 8.8 (a) illustrates a free cutting steel. Learn more about Stack Overflow the company, and our products. The higher the carbon potential, higher is the carbon concentration at the steel surface, and deeper is the carburising depth. It only takes a minute to sign up. The increase in surface hardness results in enhanced wear and fatigue resistance. One of the most popular forms of case hardening, carburization can provide steel items with varying levels of hardness. Carburising,[1] carburizing (chiefly American English), or carburisation is a heat treatment process in which iron or steel absorbs carbon while the metal is heated in the presence of a carbon-bearing material, such as charcoal or carbon monoxide. Consider the gas carburizing of a gear of 1020 steel at 927 C. Calculate the time in minutes necessary to increase the carbon content to 0.40% at 0.5 mm below the surface. Why are non-Western countries siding with China in the UN? In the present study Ti(C, N) ceramic layer was synthesized on the surface of Ti-6Al-4V alloy by pack nitro-carburizing method to improve surface properties of this alloy. 8.4). He can be reached at, 2018 Media Solutions inc. All rights reserved, Carbon Diffusion and Carburizing Parameter Selection, IHEA rings in 2023 with some great events, Quench factor analysis: C-curve determination, Mark your calendars for these important conference dates, Premier Furnace Specialists Inc./BeaverMatic, Linear-elastic fracture toughness testing, Gear inspection methods from heat-treat simulation, Hybrid Forging: Advances in Open Die and Closed Die Forging, Single-Piece, High-Volume, and Low-Distortion Case Hardening of Gears. Do you have a need for carburized items? His focus centers around material selection, evaluation, and application in engineering and industry, including material strengthening and hardening, thermal processing and optimization, relationship between processing, microstructure and property, and failure analysis. Vacuum carburization [3, 7-9] (also referred to as low pressure carburizing) is performed by heating the part in a vacuum furnace to austenitization temperature and introducing a carburizing gas at low pressure into the chamber for a short period of time [1, 3, 10, 16]. The need for continuous control of the endothermic generated . carburizing time calculationc'est dans les moments difficiles citationc'est dans les moments difficiles citation Longer carburizing times and higher temperatures typically increase the depth of carbon diffusion. So, 2 amp current = 1 s. The parts are held at a temperature above Ac1 in a molten salt that introduces carbon and nitrogen, or carbon alone, into the metal. The effect of time and temperature on total case depth shows that the carburizing time decreases with increasing carburizing temperature. Steel Weight Calculator; Metal Weight Calculator; Sheet Metal Bending Calculator; K Factor Calculator; . Steels which have been liquid carburized typically possess high levels of carbon and low levels of nitrogen. The carburizing period is often referred to as the boost step. This has been proven by numerous carburizing test data of different steels. A high D C. voltage when applied ionises the gas into a glowing plasma. It can be safely assumed that the surface carbon content reaches the maximum value, Cs instantly and remains constant at this value during carburising. However changes are small compared to heat-treating operations. He presented his findings, which were published in metal progress august 1943. Surface Carbon Content: In the equation, c is the concentration of carbon, t is time, x is the position or depth below the surface of the part, and d is the diffusion coefficient. While metal alloy items are being submerged in this concoction, they come into contact with a collection of carbon molecules. What is the origin of the Quadratic factor in calculation of XRD peaks? There are different types of elements or materials that can be used to perform this process, but these mainly consist of high carbon content material. The process of carburising takes place in two steps: In the first-step, the free-carbon is added i.e. The intent is to make the metal harder. Facet Ability Stone Calculator . Case depth can range from as low as 0.010", to as deep as 0.200". The plasma utilised for case-carburising is the glow discharge having high density of electrons 1 x 1012/cm2 with an average energy in the range of 1 to 10 eV, which can effectively ionize and dissociate diatomic molecules. Furthermore, when temperature is too high, the grain growth will give rise to unexpected mechanical properties. Fig. Low pressure carburizing is a thermochemical process that aims to harden the surface of metals by increasing their carbon concentration. Effective case depth is based on the 50 hrc definition. Assume the carbon content at the surface is 1.45 % and that the nominal carbon content of the steel gear before carburizing is 0.18%. The amount of these changes varies based on the type of material that is used, the carburizing process that the material undergoes and the original size and shape of the work piece. Chemistry Stack Exchange is a question and answer site for scientists, academics, teachers, and students in the field of chemistry. amounts of carburizing gas at a temperature within the range of 900-1050 C. Non-treated steel is post-cured in this environment for the time required to obtain the desired carbon prole. All Rights Reserved BNP Media. If you're buying a steel alloy simply for its surface hardness, carburized steel is easily the most affordable option. Co-Cs We can determine that a value of Cx can be calculated whereby; Cx = 0.8019 (Co - Cs) + Cs Cx = 0.8019 (0.18 - 0.8) + 0.8 Cx = 0.8019 (-0.62) + 0.8 Cx = 0.8 - 0.4971 Cx = 0.3029 (0.303) As such, the carbon content of a 0.18wt% steel alloy cam shaft at 0.8mm after 6 hours in a carburising furnace with 0.8% atmospheric carbon at 930C is 0.303%. Here x is taken in mm and t, time in hours. Nope. [4], In general, pack carburizing equipment can accommodate larger workpieces than liquid or gas carburizing equipment, but liquid or gas carburizing methods are faster and lend themselves to mechanized material handling. It shows that measured, effective case depth of gear parts covering most of the industrial application range (0.020 inch to over 0.250 inch) was in good agreement with the calculation. By heating a steel item in a carbon-dense atmosphere, said item will allow carbon atoms to attach to its surface on a molecular level. In light of this analysis, . You can find us at 903 N BLUFF RD in COLLINSVILLE, IL 62234-5820, just a short drive away from St. Louis, MO, Belleville, and St. Charles. After a time (t > 0) of carburising, the variation of carbon concentration may be taken to vary linearly from Cs at the surface (x = 0) to C0 at a distance x, the carbon content equal to the original carbon content of the steel, where x is the case depth (Fig. The charge is These equations, then act as a guide and the actual time must be obtained for the case depth for actual operating conditions. 8.5 (b). is a metallurgist with a Ph.D. degree in Materials Science and Engineering. Feb 28, 2023 (CDN Newswire via Comtex) -- MarketQuest.biz has reported that a thorough study on Global Low Pressure Vacuum Carburizing Furnaces Market 2023. Depending on the amount of time and temperature, the affected area can vary in carbon content. Low carbon steel is in contact with a high-carbon gas, liquid or solid. The carburization process is much cheaper than the production of certain steel alloys. Calculate the time necessary to increase the carbon content to 0.30 wt% at 0.030 in below the surface of the gear. Broadly the carburising furnaces can be classified into two categories: (ii) Continuous type furnaces- These are normally preferred for carburising large tonnage of similar parts with total case depth of less than 2 mm. Visit our updated, Heat & Corrosion Resistant Materials / Composites, Commercial Heat Treat Capabilities Directory, Practical Heat Treating: Basic Principles. Operation method: Place the steel parts in a carburizing medium, heat it to a temperature between 900-950 degrees and hold it there. Carburization is achieved in around 5 to 10 hours using this process. Sheet metal fabrication is the process of creating metal structures and components by cutting, bending, and shaping metal sheets. For applications where great control over gas composition is desired, carburization may take place under very low pressures in a vacuum chamber. In such cases, core hardness can be decreased by decreasing the quenching temperature. Effective case depth is based on the 550 hv definition. Processing Carburizing: Time, temperature, and carbon potential relationship to case depth are well established. It is often used to anneal metal, making it more malleable and flexible during the welding process. This gas is a reducer of carbon, causing carbon to pull from the surface of the carbon-dense items which were placed in the furnace. This amount of carbon is supplied by the diffusion of carbon from the surface of steel in time, dt, which is equal to J.dt, and thus-. Sometimes, the core may have high hardness (may be the carbon is slightly more). This is one of the reasons that carburizing is processed in an austenitic region. That satisfies all chosen , Calculadora De Razon De Cambio . In the beginning, this diffusion rate is small as the carbon gradient (and thus, the driving force for diffusion) is small between the surface and the core. However, they don't provide the internal softness needed to be intricately shaped and formed. This is done by exposing it to an atmosphere which is dense in carbon. In this article we will discuss about:- 1. In the equation $C_x$ simply means the concentration at depth x. Besides, concentration cannot be linearly added. 7.11 Determine the carburizing time necessary to achieve a carbon concentration of 0.45 wt% at a position 2 mm into an iron-carbon alloy that initially contains 0.20 wt% C. The surface concentration is to be maintained at 1.30 wt% C, and the treatment is to be conducted at 1000 C. Use the diffusion data for -Fe in Table 7.2. Posted on june 3, 2022. Plasma carburising is basically a vacuum process in which carbon is imparted to the surface of the steel as carbon-bearing ions escaping from an ionised gas or plasma for subsequent diffusion below the surface. The problem is stated as follows: (LogOut/ Determine the carburizing time necessary to achieve a carbon concentration of 0.50 wt% at a position 1.2 mm into an iron-carbon alloy that initially contains 0.18 wt% C. The surface concentration is to be maintained at 1.1 wt% C, and the treatment is to be conducted at 1200C. 8.7 Hardness profit of case in case-handed steel DC is 1 mm. This is similar to temperature, although the effect of the former is not as remarkable as the latter. Also a positive furnace pressure is required so that air does not enter into the furnace which is possible in sealed-quench furnace. The workpiece surface must be free from contaminants, such as oil, oxides, or alkaline solutions, which prevent or impede the diffusion of carbon into the workpiece surface. This manufacturing process can be characterized by the following key points: It is applied to low-carbon workpieces; workpieces are in contact with a high-carbon gas, liquid or solid; it produces a hard workpiece surface; workpiece cores largely retain their toughness and ductility; and it produces case hardness depths of up to 0.25 inches (6.4mm). The frequency response of a l, Busbar Size Calculation Chart Pdf . In oxy-acetylene welding, a carburizing flame is one with little oxygen, which produces a sooty, lower-temperature flame. One of the most sophisticated and common forms of case hardening is carburizing. R.P. 8.27 (ii) compares the case depth of conventional gas, vacuum and plasma carburising. Here Dyc does vary with concentration, but making it constant gives simple solution to the equation which is quite applicable to practical problems. It gives high carburising rate. Thus, for such applications, alloy steels are used to have good core hardenability so that martensite forms throughout the part. With still higher surface carbon content, the case becomes very brittle due to coarse cementite network formed in it. Effective case depth is based on the 550 hv definition. If the level of residual methane in the furnace atmosphere continuously increases with carburizing time beyond the point of carbon potential stabilizing, the . Plasma carburising has many advantages. A schematic picture of plasma furnace is illustrated in Fig. The difference is that it doesn't necessitate the presence of carbon-dense items. This type of work, What is Welding? 3. Normal gas carburising profile at 900 for 240 minutes can be obtained in half the time in plasma carburising at the same temperature. Evaluation of the Depth of Carburisation through Ficks Law: The depth of carburisation is the distance below the surface to definite carbon content, or the total depth of carbon penetration. The volume to be carburized is cal-culated using the following equation: V = A s xD c (2) Next we calculate the total carbon . 60-60 x 1.5 = 51 HRc). By D. Scott MacKenzie, Ph.D., FASM - August 11, 2017 PDF Carburizing is the addition of carbon to the surface of low carbon steels. Calculated results with process control: (a) carburizing curve; (b) carbon concentration at surface and at 0.5 mm below surface as a function of time; (c) gradient of carbon concentration after carburizing. Plagiarism Prevention 5. Short story taking place on a toroidal planet or moon involving flying. Before lighting the furnace, make sure that air switches, exhaust fans, automatic shut-off valves, and other safety precautions are in place. Where D is the diffusion coefficient of Carbon in iron, stated above as 9 x10-8 cm2/s. It was concluded that the optimum combination of mechanical properties is achieved at the carburizing temperature of 950C soaked for 120 minutes followed by oil quenching and tempered at 500C. Normally, the desired surface carbon content is lower than the solubility limit, because having carbon content beyond 0.8% doesnt increase the hardness of martensite obtained on hardening, as more and more retained austenite is obtained, which is quite undesirable, as it leads to lower hardness values and is a potential source of dimensional and microstructural instability. As carburising proceeds, the amount of carbon atoms added per sec to the steel is given by Ficks first law as: where, J is the net carbon flux per unit area per second, Dcy is the diffusion coefficient of carbon in austenite. Fig. This is also called effective case depth. The presence of alloying elements has strong effects on the structure of the carburised layer, mechanism of its formation and the rate of diffusion. Carburizing is carried out at temperatures above the transformation of steel, so that quenching and tempering to develop the hardness in the case and core is required. When low carbon steel at high temperature is in contact with an atmosphere of high carbon activity, carbon is absorbed at the surface. It gives blind hole penetration. Assume the carbon content at the surface of the gear is 1.15 wt %. The temperature is typically 925 C and the carburizing times range from 2 hours for a housing with a depth of 1 mm to a maximum of 36 hours for a housing with a depth of 4 mm. Fig. Carburizing is typically performed after a part has been constructed to its final form. Surface hardness can be as high as 62 - 64 HRC. Gas carburizing. Welding is a fabrication process that joins two or more pieces of metal or thermoplastics together by heating the material to its, What is a Flat belt pulley? The equations 8.7 and 8.9 may not be strictly valid for the curved surfaces as these equations have been obtained for planar steel surfaces, (when carbon diffuses perpendicular to the surface), however for most practical carburising problems, it has been seen that these equations give results even with curved surfaces with not much error. Flat belt pulleys are used in transmission systems that are driven by flat belts, typically high-speed, low-power applications in, Cast iron is known for its high carbon content, brittle nature, ability to retain heat, good thermal conductivity, excellent castability and machinability, and good wear, Pulleys are simple machines that are used to change the direction of an applied force and to reduce the amount of force needed to move, Pulleys are commonly used in shipping and marine applications, as well as for industrial equipment and heavy machinery. ANSI/AGMA 2001-D04 "Fundamental Rating Factors and Calculation Methods for . Asking for help, clarification, or responding to other answers. Is it possible to create a concave light? When the iron or steel is cooled rapidly by quenching, the higher carbon content on the outer surface becomes hard due to the transformation from austenite to martensite, while the core remains soft and tough as a ferritic and/or pearlite microstructure.[2]. Carburising, [1] carburizing (chiefly American English), or carburisation is a heat treatment process in which iron or steel absorbs carbon while the metal is heated in the presence of a carbon-bearing material, such as charcoal or carbon monoxide. This vat is filled with a mixture of substances, typically including cyanide and salt. In pack carburizing, the workpiece and carbon are enclosed in a container to ensure that contact is maintained over as much surface area as possible. 13.4" diagonal Chevrolet Infotainment 3 Premium System with Google built-in, includes multi-touch display, AM/FM/SiriusXM 1 radio capable. Charcoal, molten salt, and carbon-containing gases such as natural gas and propane are used accordingly.if(typeof ez_ad_units!='undefined'){ez_ad_units.push([[728,90],'engineeringchoice_com-banner-1','ezslot_0',869,'0','0'])};__ez_fad_position('div-gpt-ad-engineeringchoice_com-banner-1-0'); There are three types of carburization that are commonly used: All three processes are based on the transformation of austenite into martensite during quenching. 0 5 10 15 20 25 30 35 40 45 Time, (min.) Carburising is achieved by keeping the low carbon steel in contact with solid, liquid or gaseous atmosphere of high carbon activity at high temperatures, i.e., in the austenitic range. Can the Spiritual Weapon spell be used as cover? By means of a carbonaceous medium (gas or salts) the outside layer of a carbon poor component is enriched with carbon by means of carbon diffusion. It leads to the development of a combination of high surface hardness as well as high toughness and impact strength due to core, as required for many engineering parts in service life such as heavy duty gears, cams, ball bearings, bushings, rock-drilling bits, etc. Content Filtration 6. K, and T is the absolute temperature (K). Carbonitriding is carried out on a similar section of steel, although the carbon content by mass can be 0.4-0.5%. Calculate the time necessary to increase the carbon content to 0.35% at 0.40 mm below the surface of the gear. Systems typically use multiple pulleys to increase, Metal cutting is a fundamental process in manufacturing, and having the right tools for the job is crucial for achieving accurate and efficient results. as 0.8%, (3.) Here components after carburising are discharged from the furnace into a vestibule which covers the oil-quench tank. . [3] Carburization can be used to increase the surface hardness of low carbon steel.[3]. Mn, Si, Ti intensify oxidation. Bluetooth 2 streaming audio for music and select phones. In this work, W skeletons were reacted with C by vacuum pulse carburization for different carburization times. Another major benefit of carburized steel is that it possesses a soft interior. This is done by supplying a carburizing gas in a furnace containing non-treated steel. There are several methods, and hotter isn't always better. Looking to benefit from the magic of carburizing? He presented his findings, which were published in Metal Progress August 1943. Contact ustoday to discuss your carburization needs! This is also called effective case depth. The process is environmentally friendly. Carburizing is a time/temperature process; the carburizing atmosphere is introduced into the furnace for the required time to ensure the correct case depth is achieved. Depending on the amount of time and temperature, the affected area can vary in carbon content. carburising equation. Carburization is the most cost-effective option. Applications which require high core strength to support the case in heavy duty conditions or, where the stress-gradients between the surface and the interior of a part in service are high to produce sub-surface cracks in un-hardened core, alloy steels are used with good core hardenability that form martensite throughout a carburised part. and cookie policy to learn more about the cookies we use and how we use your as 0.18wt%, (2.) It has been seen that case depth determined like this agrees well with the measurements done by metallographic test and represents normally a point about 0.04% carbon higher than the core carbon content. Steel, aluminum, brass, copper, or titanium, Sheet metal fabrication techniques are used to create a variety of intricate parts and components with the highest degree of accuracy. In fact, you might even be able to pull it off in a garage or home workshop. As metals are made up of atoms bound tightly into a metallic crystalline lattice, the carbon atoms diffuse into the crystal structure of the metal and either remain in solution (dissolved within the metal crystalline matrix this normally occurs at lower temperatures) or react with elements in the host metal to form carbides (normally at higher temperatures, due to the higher mobility of the host metal's atoms). Tue oct 22 11:19:16 2002 Case depth is typically measured as total or effective. How can we prove that the supernatural or paranormal doesn't exist? This makes it especially useful for when you're trying to manufacture intricate metal items with hard surfaces (ie. Image Guidelines 4. Reliable Vacuum Supply for Plasma Nitriding, Heat Treatments and Critical Quenching Ratesin Additively Manufactured AlSiMg Alloys, Heat treatment of PM parts by hot isostatic pressing, Titanium alloy microstructure fingerprint plots from in-process machining. Fig. Carbonitriding is a modification of gas carburizing in which ammonia is added to the methane or propane and is the source of nitrogen. After attaining the carburising temperature and when the charge has been uniformly heated, calculated amount of enriching gas (10 15% Natural gas) is added to get around a carbon potential of 1.3%. 8.5 (c) illustrates the curved line for actual carbon distribution in a carburised low carbon steel. help you have the best experience while on the site. Calculate the carbon level at a depth of 0.8mm after 6 hrs. The temperature is typically 925 C and the carburizing times range from 2 hours for a housing with a depth of 1 mm to a maximum of 36 hours for a housing with a depth of 4 mm. Carburising is done in the austenitic range (because the solid solubility of carbon in austenite is much higher than in ferrite, and which increases with the rise of temperature), usually between 850C to 950C, but commonly at 900 to 925C mainly not to decrease the life of furnace parts. paper calculates the effective case depth governed by carburizing temperature, time, carbon content of steel, and carbon potential of atmosphere.
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