Cast iron platform heat treatment process

Heat treatment process of cast iron platform: cast iron platform (also known as cast iron plate) and bed casting products as a large casting must be heat treated to improve its performance and improve the intrinsic quality of cast iron plate. Metal heat treatment is one of the important processes in mechanical manufacturing. Compared with other processing methods, heat treatment generally does not change the shape of the workpiece and the overall chemical composition, but changes the microstructure inside the workpiece or changes the chemical composition of the surface of the workpiece. , to give or improve the performance of the workpiece. It is characterized by improved internal quality of the workpiece.
In order to make the metal workpiece have the required mechanical properties, physical properties and chemical properties, in addition to the rational selection of materials and various forming processes, heat treatment processes are often essential. Steel is the most widely used material in the machinery industry. The microstructure of steel is complex and can be controlled by heat treatment. Therefore, the heat treatment of steel is the main content of metal heat treatment. In addition, aluminum, copper, magnesium, titanium, and the like can also be modified by heat treatment to obtain different mechanical properties, physical properties, and chemical properties.
The overall heat treatment is a metal heat treatment process that heats the workpiece as a whole and then cools it at an appropriate speed to change its overall mechanical properties. The overall heat treatment of steel has four basic processes: annealing, normalizing, quenching and tempering.
1: Annealing type of annealing heat treatment: Common annealing processes include: recrystallization annealing, stress relief annealing, spheroidizing annealing, and complete annealing. The purpose of annealing: mainly to reduce the hardness of metal materials, improve plasticity, to facilitate cutting or pressure processing, reduce residual stress, improve the homogenization of tissue and composition, or prepare the tissue for the subsequent heat treatment.
Complete annealing and isothermal annealing Complete annealing, also known as recrystallization annealing, is generally referred to as annealing. This annealing is mainly used for casting, forging and hot-rolled profiles of various carbon steels and alloy steels with sub-eutectoid compositions, and sometimes for welding. structure. It is often used as a final heat treatment for some non-heavy workpieces or as a pre-heat treatment for certain workpieces.
Spheroidizing annealing Spheroidizing annealing is mainly used for hypereutectoid carbon steel and alloy tool steel (such as steel cutting tools, measuring tools, and steels used in molds). Its main purpose is to reduce hardness, improve machinability, and prepare for later quenching.
Stress relief annealing stress relief annealing, also known as low temperature annealing (or high temperature tempering), is mainly used to eliminate residual stresses in castings, forgings, welded parts, hot rolled parts, cold drawn parts, etc. If these stresses are not eliminated, it will cause deformation or cracking of the steel after a certain period of time or during subsequent cutting operations.
2. Quenching The most common cooling media we use for quenching are brine, water and oil. Brine-quenched workpieces are easy to obtain high hardness and smooth surface, and it is not easy to produce hard spots that are hard to quench, but it is easy to deform the workpiece seriously and even crack. The use of oil as a quenching medium is only suitable for the quenching of some alloy steels or small-sized carbon steel workpieces with relatively high stability of supercooled austenite.
3. The purpose of tempering and tempering is as follows:
1. Reduce brittleness, eliminate or reduce internal stress, there is great internal stress and brittleness after quenching steel. If it is not tempered in time, it will cause deformation or even cracking of steel.
2. Obtaining the mechanical properties required for the workpiece, the workpiece has high hardness and high brittleness after quenching. In order to meet the different performance requirements of various workpieces, the hardness can be adjusted by appropriate tempering to reduce the brittleness and obtain the required toughness. Plasticity.
3. Stabilize the workpiece size 4. For some alloy steels that are difficult to soften by annealing, high temperature tempering is often used after quenching (or normalizing) to properly aggregate the carbides in the steel and reduce the hardness to facilitate cutting.
4, the production of cast iron platform also needs heat treatment process of normalized steel parts - the heat treatment type of normalized steel is divided into two categories: overall heat treatment and surface heat treatment. Commonly used integral heat treatments include annealing, normalizing, quenching and tempering; surface heat treatment can be divided into surface quenching and chemical heat treatment.
Normalizing is the process of heating a steel piece to a critical temperature above 30-50 ° C. After a suitable time of cooling, the heat treatment process is cooled in still air. The main purpose of normalizing is to refine the structure, improve the performance of the steel, and obtain a tissue that is close to equilibrium.
Compared with the annealing process, the main difference is that the normalizing cooling rate is slightly faster, so the production cycle of the normalizing heat treatment is short. Therefore, when annealing and normalizing can also meet the performance requirements of parts, use normalizing as much as possible. Most of the medium and low carbon steel billets are generally normalized by heat treatment. Generally, alloy steel billets are often annealed. If normalized fire is used, the hardness is higher after normalizing, which is not suitable for cutting.
A qualified product must be strictly passed through each link, and the small differences in each link will ultimately affect the quality of the product. Our company specializes in manufacturing all kinds of cast iron flat plates, cast iron platforms, scribing platforms, scribing plates and other measuring tools, carefully making every detail and carefully crafting each product.

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