Heat Treatment of Steel

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  • Topic: Steel, Austenite, Carbon steel
  • Pages : 3 (982 words )
  • Download(s) : 68
  • Published : February 27, 2013
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Introduction:
In early 60’s a historical survey of metallurgical research where bainite was discovered. This microstructure was named by Bian’s colleageus at the United States Steel Corportion. At first microstructure of martensite and bainite seem similar, which had many aspects on their transformation of mechanisms. Microstructure of bainite seems to be darker than the mastenisite under a microscope. The reason behind bainite structure became useful was because of its hardness. There are few Heat treatments that steel can be tested by such as Annealing, quenching Harderning, and Normalizing.

Body
Bainite is A combination of ferrite and cementite in ferrous metals that is harder than pearlite. Bainite contains needlelike grain structures, and it requires an initial rapid cooling followed by gradual cooling.IT is also a micrstrucutre that is another form of steels at certain temperatures from 250-550°C. “Pearlite formation is found from the eutectoid temperature (727°C) down to 400°C. Below 400°C, the pearlite microstructure is no longer formed.” (TEXTBOOK). Annealing is a type of heat treatment to specific steels. Purpose of using annealing is to soften steel machining and to remove all strains. Temperature that is required for annealing should be above a critical point which can varies different steels. Some steels such as low carbon and high carbon steel are annealed roughly about 1400 to 1600 degree F. Temperature should be maintain to fully heat the specimen. It is very important to care about how you follow the procedure of heating steel to a specific temperature cause we don’t want to make steel to reach above hardening point or Decalescence. If steel is heated above a critical point, then it should be cool down slowly because the grain of annealed steel is coarseness. “Process annealing is done by raising temperature just below the Ferrite-Austenite region line A1 on diagram.” Annealing is also used to hardened parts which are made out of...
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