The role of thermal treatment is to improve the material performance of the steel pipe and precision steel pipes, eliminate residual stress, and improve the cutting processing performance of steel pipe metals.According to different purposes, thermal treatment process can be divided into two categories: preparing heat treatment and final thermal treatment.
1. Prepare heat treatment
The purpose of preparing heat treatment is to improve processing performance, eliminate internal stress, and prepare good gold -phase tissue for final thermal treatment.Its thermal treatment technology includes annealing, positive fire, timeliness, and quality adjustment.
(1) Antuction and positive fire
Antuction and positive fire are used to rough through heat processing.Carbon steel and alloy steel with a carbon content greater than 0.5%. In order to reduce its hardness and easy cutting, annealing treatment is often used; carbon -containing carbon steel and alloy steel with less than 0.5%, to avoid the knife when the hardness is too low.And use positive fire treatment.The annealing and torch can still refine the grains and uniformly organize it to prepare for future thermal treatment.Antuction and fire are often arranged after rough manufacturing and before rough processing.
(2) Time processing
The time processing is mainly used to eliminate the internal stress generated in rough manufacturing and mechanical processing.
In order to avoid excessive transportation workloads, for parts with general accuracy, it can be arranged once before refinement processing.However, parts with higher accuracy (such as the box of the benchmarking bed, etc.) should be arranged twice or the timeliness processing process twice or several times.Simple parts generally do not have timely processing.
In addition to the casting, for some precision parts (such as precision screws) with poor rigidity, in order to eliminate the internal stress generated in processing, stabilize the processing accuracy of the parts, and often arrange multiple timeliness between rough processing and semi -precision processing.Some axis parts are processed, and timely processing must be arranged after the school direct process.
(3) Restamination
The quality adjustment means that high temperature recovery treatment is performed after quenching. It can obtain a uniform and detailed recovery cable -generated tissue, which is prepared for subsequent surface quenching and nitrogen seepage treatment. Therefore, the quality adjustment can also be used as preparation of heat treatment.
Because the comprehensive mechanical properties of the parts are good, parts that require high hardness and abrasion -resistant parts can also be used as the final thermal treatment process.
2. Final thermal treatment
The purpose of the ultimate heat treatment is to improve mechanical properties such as hardness, abrasion resistance and strength.
(1) quenching
The quenching has surface quenching and overall quenching.The surface quenching is widely used due to deformation, oxidation and decarburization, and the surface quenching also has the advantages of high external strength and good abrasion resistance, while the internal maintains good toughness and strong anti -impact.In order to improve the mechanical properties of surface quenching parts, heat treatment such as quality adjustment or positive fire is often required as preparation of heat treatment.The general process route is: feeding-forging-forward fire (annealing)-Rough processing-quality adjustment-semi-precision processing-surface quenching-precision processing.
(2) Carburizing quenching
Crystal carburizing quenching is suitable for low -carbon steel and low alloy steel. First increase the carbon content of the surface layer of the parts. After quenching, the surface layer obtains high hardness, and the heart is still maintaining a certain strength and high toughness and plasticity.Carbilide is divided into overall carburizing and local carburizing.When a local carburization, anti -seepage measures should be taken (copper plating or anti -seepage material).Because the carburizing quenching deformation is large, and the depth of carburizing is generally between 0.5 and 2mm, the carburizing process is generally arranged between semi -essence and precision processing.
Its process route is generally: feeding-forging-forward fire-thick, semi-essence processing-carburizing quenching-precision processing.
After the non -carburizing part of the local carburizing part is increased, the process of the excess carbon layer should be arranged when the excess carburizing layer is removed when the excess carburizing layer is removed.
(3) Nitrogen seepage treatment
Nitrogen is a treatment method for nitrogen atoms into the metal surface to obtain a layer of nitrogen -containing compound.The nitrogen seepage layer can improve the hardness, abrasion resistance, fatigue strength and corrosionability of the surface of the part.Due to the low temperature of the nitrogen seepage, the deformed deformation, and the relatively thin nitrogen seepage layer (generally no more than 0.6 ~ 0.7mm), the nitrogen seepage process should be arranged as much as possible.Create the high temperature recovery of stress.
