L As its amount increases, a white stream increases along with it in the inner cone. Carburizing Process and Carburizing Steels Carburizing is one of the most widely used surface hardening processes. answer choices . It is obtained by gradually opening the oxygen valve to shorten the acetylene flame until a clearly defined inner cone is visible. There are three basic flame types: neutral (balanced), excess acetylene (carburizing), and excess oxygen (oxidizing) as shown below. The carburizing flame has excess acetylene, the inner cone has a feathery edge extending beyond it. 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. Heating values of fuel gases are shown in table 11-3. They impart a low temperature soaking heat to the parts being soldered. J The reducing flame is the flame with low oxygen. 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. The resulting flame is known as Carburizing Flame or Reducing Flame. A slight feather flame of acetylene is sometimes used for back-hand welding. Therefore, it is called a reducing flame. Components remain proportionate to the carburized case hardening depth requirement for a … An oxidizing action can be obtained by increasing the oxygen flow, and a reducing action will result from increasing the acetylene flow. The flame tends to be slightly purple and inner cone is pointed if the flame is properly adjusted. **Neutral flame. Published on December 17, 2019December 1, 2019. Are there any OSHA regulations that need to be taken into account when using thermal insulating coatings? This type of flame is mostly suitable to weld high carbon steel and other metallic substances which do not absorb carbon. Carburizing Process Carburizing Flame Flame of carburization is the second most important one in the types of welding flames. This white feather is called the acetylene feather. An oxidizing flame should not be used for welding steel because the deposited metal will be porous, oxidized, and brittle. 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. Carburizing flames are used for welding and heating operations as well as in welding steel surfaces. The position of the flame to the molten puddle can be changed, and the heat controlled in this manner. Methyl-acetylene-propadiene, MAPP. (1.6 to 3.2 mm) long at the end of the cone to ensure that the flame is not oxidizing. Oxidizing welding flames are produced when slightly more than one volume of oxygen is mixed with one volume of acetylene. D Carefully start oxygen flow and increase until flame goes . V 3. R A carburizing flame is used in hardfacing and similar processes to obtain fusion between base metal and … The flame burns at 550°F. The neutral or balanced flame is obtained when the mixed torch gas consists of approximately one volume of oxygen and one volume of acetylene. O T 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). Propylene is intermediate between propane and MAPP gas. 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. Carburizing flames are obtained with MAPP gas when oxyfuel ratios are around 2.2:1 or lower. 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. Carburizing Flame has three cones or zones,they are:-1) First one is called inner cone and is white in colour. When used in silver solder and soft solder operations, only the intermediate and outer flame cones are used. The metal flows easily without boiling, foaming, or sparking. 4. When the feather disappears, the oxyfuel ratio is about 2.3:1. Adjusting a MAPP gas flame. The length of the intermediate cone is an indication of the ratio of excess acetylene in the flame. The ratio of oxygen and acetylene is 1.5:1. There are two clearly defined zones in the neutral flame. Carburizing Flame. Surrounding this is a light blue flame envelope or sheath. Neutral Flame. This white feather is called the acetylene feather. When the flame is properly adjusted, the inner cone is pointed and slightly purple. P Affiliate Disclosure: This post may contain links that will earn us a commission at no cost to you. 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. In most cases, the amount of excess oxygen used in this flame must be determined by observing the action of the flame on the molten metal. 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. This flame will ruin most metals and should be avoided. There is a clearly defined bluish-white inner cone, white intermediate cone indicating the amount of excess acetylene, and a light blue outer flare envelope. It is often used to anneal metal, making it more malleable and flexible during the welding process. 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