Aging treatment of castings

Why do machine tool bed castings need tempering treatment: Steel is the most widely used material in the machinery industry. The microstructure of steel is complex and can be controlled by heat treatment, so the heat treatment of steel is the main content of metal heat treatment.

Why do machine tool bed castings need tempering treatment: Steel is the most widely used material in the machinery industry. The microstructure of steel is complex and can be controlled by heat treatment, so the heat treatment of steel is the main content of metal heat treatment. In order to make the machine tool castings have the required mechanical properties, physical properties and chemical properties, in addition to the reasonable selection of materials and various forming processes, the heat treatment process is indispensable. In addition, aluminum, copper, magnesium, titanium, etc. and their alloys can also change their mechanical, physical and chemical properties through heat treatment to obtain different performance. Overall heat treatment is a metal heat treatment process that heats the cast iron plate, cast iron bent plate or machine tool bed casting as a whole, and then cools it at an appropriate rate to change the overall mechanical properties of the cast iron platform, plate, cast iron bent plate or machine tool bed casting.

Heat treatment of machine tool castings is an important process in mechanical manufacturing. Compared with other processing technologies, heat treatment generally does not change the shape and overall chemical composition of the workpiece, but rather changes the microstructure inside the workpiece or the chemical composition of the cast iron platform and the surface of the machine tool casting to give or improve the performance of the workpiece. Its characteristic is to improve the intrinsic quality of the cast iron platform and the machine tool bed casting. As a large casting, the machine tool bed casting must undergo aging treatment to improve its own performance and improve the intrinsic quality of the bed casting. There are four basic processes for the overall heat treatment of machine tool bed castings, bed columns, machine tool workbenches, etc., namely annealing, normalizing, quenching and tempering. The tempering process should be strictly followed when tempering the machine tool bed casting. Support ribs should be added to the parts with dense ribs or easy deformation to prevent deformation and fracture caused by the tempering temperature. A dedicated person should be in charge of the tempering furnace thermometer to control the temperature in time to prevent the temperature from being too high or too low, which will have a great impact on the tempering workpiece.

Several purposes of tempering castings

1. Reduce brittleness and eliminate or reduce internal stress. After quenching, steel parts have great internal stress and brittleness. If they are not tempered in time, they will often deform or even crack.

2. Obtain the mechanical properties required by the workpiece. After quenching, the workpiece has high hardness and high brittleness. In order to meet the requirements of different performances of various workpieces, the hardness can be adjusted by appropriate tempering, the brittleness can be reduced, and the required toughness and plasticity can be obtained.

3. Stabilize the size of the workpiece

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.