On 2018-08-08 14:48:54
Heat treatment in machining process position and function
Main machining steps of parts:
Blanking - annealing (braising), normalizing - Roughing - aging treatment (applicable to castings and weldments), quenching and tempering - semi finishing - surface quenching (carburizing, carburizing and quenching) - finishing - bluing (blackening) chromium plating, galvanizing, etc. - deburring - Inspection - packaging, etc.
1、 Function and arrangement of annealing and normalizing
1. Annealing is used for hot worked blanks. In order to reduce the hardness of metal and cut it easily, carbon steel and alloy steel with carbon content more than 0.5% are usually annealed.
2. Normalizing is used for the carbon steel or alloy steel whose carbon content is less than 0.5% after hot processing. In order to avoid the cutting with too low hardness is sticking to the cutter, normalizing is used.
After annealing and normalizing, the grains can be refined and the structure is even, which is good for the later heat treatment.
Annealing and normalizing are usually arranged after rough manufacturing and before rough machining.
2、 The function of aging treatment and the position of arrangement
Aging treatment is mainly used to eliminate the internal stress produced in the process of rough manufacturing and machining. It is better to arrange it after rough machining and before semi finishing. In order to avoid too much transportation work, for parts with low accuracy requirements, it is usually enough to arrange an aging treatment after rough machining. In addition to castings, for some precision parts with poor rigidity, in order to eliminate the internal stress generated in the processing, the processing accuracy of stable parts is often arranged multiple aging treatment between rough machining, semi finishing and finishing. Some shaft parts processing in the straightening process also requires the arrangement of aging treatment.
3、 The role and arrangement of tempering
Quenching and tempering means high temperature tempering treatment after quenching. It can obtain uniform and fine sorbite structure, which is prepared for reducing deformation during surface quenching and nitriding treatment. Therefore, quenching and tempering can be used as preparatory heat treatment.
Due to the better comprehensive mechanical properties of the parts after quenching and tempering, some hardness and wear resistance can also be used as the final heat treatment process.
Quenching and tempering treatment is usually arranged after roughing and before semi finishing.
4、 The function of surface quenching and its arrangement
Function: improve the hardness, wear resistance, strength and other mechanical properties of parts. The treatment process includes quenching, carburizing and quenching, nitriding, etc.