In the production process, and sometimes there will be a shortage of the haggard fire hardness. This is a common defect in the heat treatment and quenching 'process. "Hardness" Sometimes performance for the entire workpiece hardness value, and sometimes the local hardness is not enough or soft point. Quenching insufficient hardness of many reasons, and raw materials, heating process, the cooling medium, cooling methods, as well as the tempering temperature, etc. are closely related. Once the production of this must be specifically analyzed before for the title, the right to be addressed. Below only in respect of factories often appear to talk about my views.
1, furnace or into the cooling tank and improper reasons for cause, should be amended to the process temperature maintenance check temperature control system, installed furnace, the workpiece interval placed reasonably uniform, dispersed into the groove, prohibit the accumulation of bundles into the slot cooling.
2, the quenching temperature is too high, which is the set temperature improper temperature control system error caused by the process, should be amended process temperature maintenance check temperature control system.
3, after tempering, which is the tempering temperature is set too high, the temperature control system failure error or furnace temperature is too high into the furnace caused the process temperature should be amended, maintenance check temperature control system, furnace installed not higher than the set entry.
Improper cooling, because the pre-cooling time is too long, inappropriate choice of cooling medium, temperature of quenching medium is getting high cooling performance dropped, stirring bad or the slot temperature, the faster measures: released into the tank; grasp the quenching medium cooling characteristics; oil temperature of 60 to 80 ℃, the water temperature below 30 ℃, when the quenching large amount leaving the cooling medium temperature, should be added to the cooling and quenching medium, or to switch to other cooling slot cooling; strengthen the mixing of the coolant; in Ms +50 ℃ when removed.
5, decarburization, which is caused by the raw material residues decarburized layer or quenching the precautionary measures for the controlled atmosphere is heated, the salt bath is heating, vacuum furnace, box furnace packing protection or oxidation coating; machining I the amount of increase of 2 ~ 3mm.
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