Machinability
——Hot processing performance refers to thermoplasticity, processing temperature range, etc.;
Hot work die steel - cold workability, refers to cutting, grinding, polishing, cold drawing and other processing properties.
Most of the cold work die steels belong to hypereutectoid steel and lysitic steel, and the hot working and cold working properties are not very good. Therefore, the process parameters of hot working and cold working must be strictly controlled to avoid defects and waste. On the other hand, by increasing the purity of the steel, reducing the content of harmful impurities, improving the microstructure of the steel to improve the hot working and cold working properties of the steel, thereby reducing the production cost of the mold.
In order to improve the cold workability of die steel, since the 1930s, the development of various easy-to-cut processing elements such as S, Pb, Ca, Te, etc. into the mold steel or the elementalization of carbon in the die steel has been developed. Die steel is cut to further improve its cutting performance and grinding performance, reduce tool abrasive consumption and reduce costs.
Hardenability and hardenability
The hardenability depends mainly on the chemical composition of the steel and the original microstructure before quenching; the hardenability depends mainly on the carbon content in the steel. For most cold work die steels, hardenability is often one of the main considerations. For hot work die steel and plastic die steel, the general die size is large, especially for the manufacture of large molds, the hardenability is more important. In addition, for various molds with complicated shape and easy heat treatment deformation, in order to reduce the quenching deformation, it is often possible to use a quenching medium with a weak cooling capacity, such as air cooling, oil cooling or salt bath cooling, in order to obtain the required hardness and hardened layer. For depth, it is necessary to use a mold steel with better hardenability.
Quenching temperature and heat treatment deformation
In order to facilitate the production, the quenching temperature range of the mold steel is required to be as wide as possible. Especially when the mold is partially quenched by flame heating, it is difficult to accurately measure and control the temperature, and the mold steel is required to have a wider quenching temperature range.
When the mold is heat treated, especially during the quenching process, volume change, shape warpage, distortion, etc. are required. In order to ensure the quality of the mold, the heat treatment deformation of the mold steel is required to be small, especially for the precision mold with complicated shape, which is difficult to be trimmed after quenching. For the degree of heat treatment deformation is more demanding, it should be made of micro-deformed die steel.
Oxidation and decarburization sensitivity
In the heating process, if the oxidation and decarburization occur, the hardness, wear resistance, service performance and service life of the mold will be reduced; therefore, the mold steel is required to have good oxidation and decarburization sensitivity. For mold steels with higher molybdenum content, due to strong oxidation and decarburization sensitivity, special heat treatment, such as vacuum heat treatment, controlled atmosphere heat treatment, salt bath heat treatment, etc., is required.
other factors
In the selection of die steel, in addition to the performance and process performance must be considered, the versatility of the die steel and the price of the steel must also be considered. Die steel is generally used in small quantities. In order to facilitate material preparation, the versatility of steel should be considered as much as possible, and mass-produced general-purpose mold steel should be utilized as much as possible to facilitate procurement, material preparation and material management. In addition, a comprehensive analysis must be carried out economically, taking into account the manufacturing costs of the mold, the production batch of the workpiece, and the cost of the mold allocated to each workpiece. Comprehensive analysis from the technical and economic aspects to finally select a reasonable mold material.
Fiber Glass Tape Measure,Rubber Tape Measure,Steel Tape Measure,Mini Retractable Tape Measure
Yucheng County Ruiertuo Tools Co., Ltd. , https://www.ruiertuotools.com