- Renew or change your cookie consent, Flange Corrosion Repair & Protection: Isolating the Sealing Face, Top Corrosion Mitigation Technologies to Watch for in 2021, The Impact of Minimum & Maximum DFT Values on Coating Performance, An Intro to Pipeline Corrosion and Protection Methods, Innovative Coating Solutions for Oil Sands Equipment, Troubleshooting Cathodic Protection Systems and Function Systems. Carburizing flames are used for welding and heating operations as well as in welding steel surfaces. Carburizing Heat Treatment Process The carburizing heat treatment process for machined parts and stampings starts with austenitizing the heat-treat load in a controlled, carbon-rich atmosphere. The neutral flame should have the ratios at zero, while the amount of oxygen in the oxidizing flame can be as much as 2.5 times that of the acetylene. U    When used in silver solder and soft solder operations, only the intermediate and outer flame cones are used. Therefore, it is called a reducing flame. N    In the most primitive form of this process, the carbon source is so rich that the solubility limit of carbon in austenite is reached at the surface of the steel and some carbides may form at the surface. When the flame is properly adjusted, the inner cone is pointed and slightly purple. It obtains additional oxygen from the air and provides complete combustion. ... Carburizing flame. L    Carburizing Flame Flame of carburization is the second most important one in the types of welding flames. An oxidizing action can be obtained by increasing the oxygen flow, and a reducing action will result from increasing the acetylene flow. C    The neutral flame has a clear, well-defined, or luminous cone indicating that combustion is complete. The excess fuel decomposes to carbon and hydrogen, and the flame temperature is not as great. This flame adjustment is used for most welding operations and for preheating during cutting operations. A carburizing flame burns in three shades of blue—a light blue conical-shaped flame at the tip of the nozzle is surrounded by a darker blue flame, and both of these are enclosed by a layer of even darker blue. **Neutral flame. Affiliate Disclosure: This post may contain links that will earn us a commission at no cost to you. He has always been interested in welding from an early age and has the cuts and bruises to prove it as he set out to work with a variety of metals. 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The correct torch tip to work distance must be maintained during cutting. This flame does not oxidize metal, as there is an insufficient stoichiometric level of oxygen in this flame to consume the acetylene gas. M    The carburizing flame may add carbon to the weld metal. B    For most welding operations, this streamer should be no more than half the length of the inner cone. This type of flare burns with a coarse rushing sound. Along with induction hardening and nitriding, carburizing has become one of the most popular manufacturing processes. Carburizing Flame. Between the inner cone and the outer envelope there will be a feather which generates due to the combustion of carbon containing element. Excess fuel produces a carburizing flame. Neutral Flame. Welding Flames: Neutral, Carburizing & Oxidizing - Weld Guru Report an issue . This flame is obtained by first adjusting to neutral and then slowly opening the acetylene valve until an acetylene streamer or “feather” is at the end of the inner cone. Flame adjustment is the most important factor for successful welding or brazing with MAPP gas. When used in silver solder and soft solder operations, only the intermediate and outer flame cones are used. Carburizing flame is used in medium carbon steel, nickel, etc. answer choices . The metal flows easily without boiling, foaming, or sparking. Carburizing Flame Has Three Zones. A reducing oxyfuel gas flame in which there is an excess of fuel gas, resulting in a carbon rich zone extending around and beyond the cone. Heating values of fuel gases are shown in table 11-3. As oxygen is increased, or the fuel is turned down, the carburizing feather pulls off and disappears. As its amount increases, a white stream increases along with it in the inner cone. 3. The carburizing flame may add carbon to the weld metal. The slow opening of the gas fuel increases the ratio of it. Increasing the oxygen flame produces a lighter blue flame, a longer inner cone, and a louder burning sound. A higher ratio, such as 1.5:1, produces an oxidizing flame, which is hotter than the neutral flame but similar in appearance. 2) The intermediate one is called acetylene feather and is red in colour. For a strictly neutral flame, no whitish streamers should be present at the end of the cone. This flame will ruin most metals and should be avoided. Oxygen valve will then be increase until the inner core is shortened to about one-tenth of its original length. Carburizing pre-heat flame “Walking Up” the Flame. The reducing flame is also called the carburizing flame, since it tends to introduce carbon into the molten metal.. With certain exceptions such as welding or brazing copper and copper alloys, an oxidizing flame is the worst possible flame setting, whatever the fuel gas used. While this mode of carburizing is still practiced in parts of the world in which resources are limited, the goal of current practice in modern manufacturing plants is to control the carbon content of furnace atmospheres so th… SURVEY . This flame does not oxidize metal, as there is an insufficient stoichiometric level of oxygen in this flame to consume the acetylene gas. The flow of oxygen is then increased until the inner cone is shortened to about one-tenth of its original length. Increase fuel flow to maintain carburizing flame. Tags: Question 9 . There are three basic flame types: neutral (balanced), excess acetylene (carburizing), and excess oxygen (oxidizing) as shown below. A carburizing flame is one in which there is an excess of acetylene; This flame has three zones: The sharply defined inner cone, An intermediate cone of whitish colour, and; The bluish outer cone. Z, Copyright © 2021 Corrosionpedia Inc. - because of the short supply of oxygen, the flame has to travel for larger distances to completely burn. This kind of flame is used for welding materials that do not absorb carbon. The position of the flame to the molten puddle can be changed, and the heat controlled in this manner. For combustion of acetylene in oxygen, the stoichiometric oxygen-fuel ratio is 13.26 : 1 (based on mass) or 11.92 : 1 (based on volume). 6. Which of the following flames contains too much oxygen? X    Carburizing flames are obtained with MAPP gas when oxyfuel ratios are around 2.2:1 or lower. In oxy-acetylene welding, a carburizing flame is one with little oxygen, which produces a sooty, lower-temperature flame. Viewed 4k times 0 $\begingroup$ The problem is stated as follows: The surface of a steel gear made of 1022 steel (0.22 wt% C) is to be gas-carburized at $927$ °C. Oxidizing welding flames are produced when slightly more than one volume of oxygen is mixed with one volume of acetylene. #    37).Plain and butt welds can be used for sheets having thickness approximately _____ Ans: 25 mm. A    This is the neutral MAPP gas flame for welding, shown in figure 11-3. They impart a low temperature soaking heat to the parts being soldered. It indicates that 13.26 kg of oxygen is required for complete combustion of 1 kg of acetylene. 120 seconds . In the neutral flame, the temperature at the inner cone tip is approximately 5850ºF (3232ºC), while at the end of the outer sheath or envelope the temperature drops to approximately 2300ºF (1260ºC). Instruments such as dew point analyzers monitor the H 2 O/H 2 ratio of this equation while infrared analyzers and oxygen probes look at the CO/CO 2 ratio. To get a carburizing flame it is first necessary to create a neutral flame. The pierce height, preheat time and pierce time must be set. D    Published on December 17, 2019December 1, 2019. Many large gears were flame hardened, nitrided, or through hardened (hardness around 300 BHN) using medium carbon alloy steels, such as 4140, to avoid higher distortions related to the carburizing and hardening process. Carefully start oxygen flow and increase until flame goes . A stronger oxidizing flame is used in the welding of brass or bronze. If the acetylene feather is twice as long as the inner cone it is known as a 2X flame, which is a way of expressing the amount of excess acetylene. The coupling distance between the work and the flame is not nearly as critical with MAPP gas as it is with other fuels. If the acetylene feather is twice as long as the inner cone it is known as a 2X flame, which is … Carburizing Flame. Jeff Grill hails from Long Island, a 118 mile stretch of land that starts just off the coast of Manhattan and stretches deep into the Atlantic ocean. 5. It is generally preferred for welding. This flame is also known by its clear hissing sound. Neutral Flame. F    Q    The reducing flame is the flame with low oxygen. ... Oxidizing Flame. The steel, which is absorbing carbon from the flame, gives off heat. A carburizing flame is used in hardfacing and similar processes to obtain fusion between base metal and … G    S    The flame burns at 550°F. A carburizing flame is produced when there is an excess of acetylene gas for the amount of oxygen being consumed in an oxy-acetylene mixture, producing an acetylene-rich gas. It is often used to anneal metal, making it more malleable and flexible during the welding process. The flame zones of the carburizing flame can be divided into 3 parts. 4. An operator experience with acetylene will immediately adjust the MAPP gas flame to look like the short, intense blue flame typical of the neutral acetylene flame setting. in the control of the atmosphere carburizing process. Tags: Question 4 . To create a carburizing flame, I first achieve a neutral flame. The carburizing flame has excess acetylene, the inner cone has a feathery edge extending beyond it. The cutting speed must be set according to the cut chart. The preheat flames (low and high) must adjusted to the proper ratio of oxygen to the fuel gas. E    36).Oxygen to acetylene ratio in case of carburizing flame is _____ Ans: 0.9:1. Reducing or carburizing welding flames are obtained when slightly less than one volume of oxygen is mixed with one volume of acetylene. More of your questions answered by our Experts, An Understanding of Today's Wet Abrasive Blasting Equipment, Proper Pipeline Joint Isolation - History of Design, Flanges, and the Best Available Design, Bituminous Coatings: When and How to Use Them, A Guide to Flash Rust Prevention and Protection (free PDF). As with any other fuel gas, there are three basic MAPP gas flames: carburizing, neutral, and oxidizing (fig. Save my name, email, and website in this browser for the next time I comment. The carburizing flame has three separate flame zones. Preheating the cast iron is crucial to cut through it, and this is done by setting the cutting torch so that it produces a carburizing flame, instead of a neutral flame, and with the highest possible temperature. They impart a low temperature soaking heat to the parts being soldered. I then slowly open the acetylene valve to increase the ratio of acetylene to oxygen. K    When the feather disappears, the oxyfuel ratio is about 2.3:1. It has been in use for a long time. This causes the metal to boil. Usage of Neutral Flame welding: - Mild Steel - Stainless steel - Cast iron - Copper - Aluminum CARBURISING: The Carburizing, its s reducing flame that created when the proportion of acetylene in the mixture is higher than that required to produce the neutral flame. For tips Size 10 and above, alternately repeat steps 3 and . (1.6 to 3.2 mm) long at the end of the cone to ensure that the flame is not oxidizing. Q. There are two clearly defined zones in the neutral flame. Carburizing Flame. Trim flame to proper ratio by appearance (see guide for fuel . Carburizing process is also referred to as case hardening or case carburizing process. When the flow of acetylene is decreased or the flow of oxygen increased the feather will tend to disappear. This variation within the flame permits some temperature control when making a weld. Carburizing Flame. Y    O    Active 6 years, 3 months ago. This helps keep Weldguru a free resource for our readers. A carburizing flame is also known as a reducing flame. The length of the intermediate cone is an indication of the ratio of excess acetylene in the flame. The neutral flame is the principal setting for welding or brazing steel. An oxidizing flame can also be recognized by its distinct hissing sound. It has a temperature of approximately 5700ºF (3149ºC) at the inner cone tips. In some cases, it is desirable to leave a slight acetylene streamer or “feather” 1/16 to 1/8 in. Disclaimer: Weldguru.com is based on information from multiple sources including U.S. Army Operator Circulars, O.S.H.A and our own first hand experience with welding. The oxidizing flame, which has an excess of oxygen, has a shorter envelope and a small pointed white cone. To obtain this type of flame, the torch should first be adjusted to a neutral flame. A carburizing flame is advantageous for welding high carbon steel and hard facing such nonferrous alloys as nickel and Monel. Oxidizing Flame. A neutral MAPP gas flame has a primary flame cone abut 1-1/2 to 2 times as long as the primary acetylene flame cone. V    Carburizing Calculation. It is obtained by gradually opening the oxygen valve to shorten the acetylene flame until a clearly defined inner cone is visible. It will be hotter than the neutral frame because of excess amount of oxygen combination to acetylene, So it … Oxidizing Flame. Gas carburizing is normally carried out at a temperature within the range of 900 to 950 °C. Hence, the heat lost by convection and radiation will become considerable. It has a yellow or yellowish color due to carbon or hydrocarbons which bind with (or reduce) the oxygen contained in the materials processed with the flame. Q. MAPP gas has a high heat release in the primary flame, and a high heat release in the secondary. Same with MAPP gas flame carefully start oxygen flow and increase until flame goes a lighter blue flame or! Obtained when the flow of acetylene important one in the primary flame cone does oxidize. The flow of oxygen is then increased until the inner cone is shortened to about one-tenth of original... The slow opening of the flame is 3:2 of fuel gas, there are two clearly defined cone! 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