Usually, after the initial machining of the part, the manufacturer heats the surface of the part, thereby changing the properties of the metal material used in the part to meet the special needs of the customer, or to facilitate further processing of the metal.

If you still don’t know what heat treatment is, let us help you! In this article, we will introduce you to the definition and use of heat treatment, as well as its advantages and disadvantages.

What is heat treatment?

Heat treatment is a metalworking process. The metal or alloy workpiece is placed in a certain medium, heated to a suitable temperature, and kept at this temperature for a certain period of time, and then controlled to cool in different media at different speeds.
According to the use process, it can be divided into three categories: integral heat treatment, surface heat treatment and chemical heat treatment. According to the different heating medium, heating temperature and cooling method, each type can be divided into several different heat treatment processes.
Finishing heat treatment is a metal heat treatment process in which the workpiece is heated as a whole and then cooled at an appropriate rate to change its overall mechanical properties. The overall heat treatment generally has four basic processes: annealing, normalizing, quenching and tempering.
Surface heat treatment is a metal heat treatment process that only heats the surface of the workpiece to change the mechanical properties of the surface. In order to only heat the surface layer of the workpiece without allowing too much heat to pass into the inside of the workpiece, the heat source used must have a high energy density, that is, a larger amount of heat energy is given to the workpiece per unit area, so that the surface layer or local area of ​​the workpiece can be short-term or instantaneous. reach high temperature. The main methods of surface heat treatment are flame quenching and induction heating heat treatment. Commonly used heat sources are flames such as oxyacetylene or oxypropane, induced current, laser and electron beam.
Chemical heat treatment is a metal heat treatment process that changes the chemical composition, structure and properties of the workpiece surface. The difference between chemical heat treatment and surface heat treatment is that the latter changes the chemical composition of the workpiece surface. Chemical heat treatment is to heat the workpiece in a medium (gas, liquid, solid) containing carbon, nitrogen or other alloying elements for a long time, so that the surface of the workpiece is infiltrated with elements such as carbon, nitrogen, boron and chromium. After infiltration of elements, other heat treatment processes such as quenching and tempering are sometimes carried out. The main methods of chemical heat treatment are carburizing, nitriding, and metalizing.
The same metal, through different heat treatment processes, can obtain different structures and therefore have different properties.

Uses of heat treatment

Heat treatment can change the microstructure on the surface or inside of the metal material by heating and cooling, so as to change the physical or chemical properties of the metal, so as to control the performance of the part without changing the shape of the workpiece. Many common effects can be accomplished using heat treatment, such as increased ductility and toughness and increased wear and corrosion resistance.

Why use heat treatment?

Heat treatment is one of the important steps in the manufacturing of mechanical parts and tools, helping the parts obtain the required mechanical and chemical properties to reduce stress and prevent the parts from deforming after being put into service. Generally speaking, it can ensure and improve various properties of the workpiece, such as wear resistance, corrosion resistance, etc. It can also improve the structure and stress state of the blank to facilitate various cold and hot processing.
For example, after long-term annealing treatment of white cast iron, malleable cast iron can be obtained, which improves plasticity; the gear adopts the correct heat treatment process, and the service life can be doubled or dozens of times longer than that of the gear without heat treatment; These alloying elements have some expensive alloy steel properties and can replace some heat-resistant steels and stainless steels; almost all tools and dies need to be heat treated before they can be used.

Hope the above content can help you.