What is Heat Treatment?
Heat treatment is a process in which I change the internal microstructure of a workpiece or change the chemical composition of the surface of a workpiece to improve its performance.
When is heat treatment needed?
After the customer places the order, the sawing workshop cuts the size of the mold steel according to the customer's demand, and then goes to the machining for a series of grinding or machine milling work.
According to the demand or rough molding mold returned to the factory heat treatment, according to different material requirements, choose different processes for heat treatment.
Heat treatment process classification
Heat treatment process contains: quenching, tempering, nitriding, deep cooling, oxidation and other processes. So what do these processes mean?
First, quenching
1, what is quenching?
Steel austenitization after cooling at an appropriate cooling rate, so that the workpiece in the cross-section of all or a certain range of unstable tissue structure such as martensite transformation of the heat treatment process.
2, the purpose of quenching?
(1) to improve the mechanical properties of the metal into material or parts. For example: to improve the hardness and wear resistance of tools, bearings, etc., to improve the elastic limit of the spring, to improve the overall mechanical properties of shaft parts.
(2) improve the material properties or chemical properties of some special steel. Such as improving the corrosion resistance of stainless steel, increase the permanent magnetism of magnetic steel.
Second, tempering
1, what is tempering?
After quenching the workpiece heated to the critical point of AC1 below the appropriate temperature for a certain period of time, followed by cooling with the required method to obtain the desired organization and properties of the heat treatment process.
2, the purpose of tempering?
(1) to reduce internal stress and reduce brittleness, quenched parts there is a great deal of stress and brittleness, such as no timely tempering often produce deformation or even cracking.
(2) adjust the mechanical properties of the workpiece, workpiece quenching, high hardness, brittleness, in order to meet the different performance requirements of a variety of workpieces can be adjusted by tempering, hardness, strength, plasticity and toughness.
(3) Stabilize the size of the workpiece. Through the tempering can make the metallurgical organization tends to stabilize, in order to ensure that no further deformation in the future use of the process.
4) Improve the cutting performance of certain alloy steels.
Third, nitriding
1, what is nitriding?
Nitriding treatment refers to a certain medium at a certain temperature so that nitrogen atoms penetrate the surface of the workpiece chemical heat treatment process.
2, the purpose of nitriding?
To make products with excellent wear resistance, fatigue resistance, corrosion resistance and high temperature resistance. Nitriding treatment refers to a certain temperature in a certain medium so that nitrogen atoms penetrate into the surface layer of the workpiece chemical heat treatment process.
Deep cooling
1, what is deep cooling?
Deep cooling treatment is the metal in -160 ° C below the treatment, so that the soft residual austenite almost all converted to high-strength martensite.
2, the purpose of deep cooling?
Elimination of residual austenite (quenching and tempering residual austenite in 8-20% or so, due to austenite is very unstable, when subjected to external forces or environmental temperature change, easy to transform into martensite, and the volume of martensite is greater than the austenite, which will result in irregular expansion of the material, reducing the dimensional accuracy of the workpiece) deep cooling residual austenite is reduced to 2% or less, to reduce the residual stresses, so that the metal matrix is more stable, make the Strength of metal materials, toughness increase, red hardness significantly improve.
V. Oxidation
What is oxidation?
Steel parts through the oxidation process on the surface to generate a dense, protective oxide film, the main component is magnetic iron oxide (Fe3O4), with the role of anti-bonding, surface sulfide obtained FeS film can be both abrasion and anti-bonding effect. At the same time can improve corrosion resistance and high temperature oxidation resistance.
