Analysis and treatment methods of carbon enhancement mechanism in carbon potential protection atmosphere annealing
Local carbonization occurred during annealing treatment of diameter 34 mm 45 steel wire using STC furnace,re-sulting in subsequent cold heading cracking.By analyzing process,equipment,and raw materials,the reasons for carbon increase have been determined.When heating up from 630 ℃ in sixth stage of process to 670 ℃ in preheating stage,the process factor PF value did not reach preset value,resulting in a longer actual execution time than preset time.After shot blasting,raw materials are roughly pulled into STC furnace.Due to incomplete blowing of material surface after shot blas-ting,there is black powder.The black powder reacts with CO in furnace gas,causing analyzer to detect high CO2 content and low CO content,resulting in decrease in PF value.This causes gas generator to continuously introduce natural gas cracking gas into furnace.Due to air inlet being located on the top of furnace,materials near the top of furnace have a high carbon potential in local atmosphere,resulting in carbon increase.Corrections have been made to materials used for carbon enhancement,and preventive measures have been developed for subsequent production processes to ensure product quality.
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