What is meant by decarburisation during heating of forgings?

Release time:

2024-01-19 09:35

Forging to pay attention to a lot of things, but not every item to pay strict attention to, forging heating process decarburisation is what it means? The following article is mainly to tell you.

Steel in the heating, the surface of the carbon and furnace gas in some of the oxidising gases in the chemical reaction, resulting in the surface of the steel, the carbon content of the phenomenon known as decarburisation. Decarburisation is also the result of diffusion, on the one hand, the oxygen in the furnace gas to the steel diffusion, on the other hand, the carbon in the furnace gas to the outer surface diffusion, so that the steel in the surface of the formation of a low carbon content decarburisation layer. From the whole process, the decarburisation layer can only be formed when the decarburisation rate exceeds the oxidation rate. Factors affecting decarburisation are the same as oxidation, and are mainly affected by the chemical composition of steel, furnace gas composition, heating temperature, heating time and other factors.

The higher the carbon content of the steel, the greater the tendency to decarburisation. Certain alloying elements increase the tendency of decarburisation, such as c, w, Si, A1, etc.. Some alloying elements prevent decarburisation, such as Cr and Mn. And Ni and V have little effect on decarburisation. Furnace gas composition in the decarburisation of the strongest medium is water vapour, followed by co2 and 02, and finally H2, and increase the amount of CO can reduce the tendency to decarburisation. In the neutral medium or weak oxidising medium heating can reduce the decarburisation tendency. The higher the heating temperature and the longer the heating time, the more serious the decarburisation. When the heating temperature is higher than 1000℃, the decarburisation is weak due to strong oxidation. At higher temperatures, due to the loss of protective effect of the oxide skin off, decarburisation will occur dramatically.

Decarburisation makes the forging surface carbon crucible reduce, reduce the strength and wear resistance, decarburisation layer thickness is less than the machining allowance, on the forging performance does not have an impact, on the contrary, it will affect the quality of forging though. General measures to prevent oxidation can also prevent decarburisation.

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Processing of forgings in a forging plant

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Matters to be noted when polishing forgings

A good polishing surface for forgings should be clean, bright and flat. However, poor polishing often results in a number of polishing defects, the common ones being: pockmarks, contamination spots, scratches, trailing and shedding of non-metallic inclusions. If such defects occur, it is necessary to re-polish the sample.

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Forging plant forging products are plastically deformed through forging processing, forging processing is the use of external forces to produce plastic deformation of the raw material forging, to obtain the required size, shape and performance of the forging blanks or parts of the processing method.

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Mainly to improve their mechanical properties (strength, plasticity, toughness, fatigue strength) and reliability. This requires better application of the theory of plastic deformation of metals; application of materials with better intrinsic quality, such as vacuum-treated and vacuum-smelted steel;

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The existence of forging defects, some will affect the quality of subsequent processes or processing quality, some seriously affect the performance and use of forgings, and even greatly reduce the service life of manufactured parts, endangering safety.

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Usually the heat treatment of large forgings is combined with the cooling of the forgings with each other, due to the large cross-section size of large forgings and the complexity of the production process.

What is meant by decarburisation during heating of forgings?

Forging to pay attention to a lot of things, but not every item to pay strict attention to, forging heating process decarburisation is what it means? The following article is mainly to tell you.