Alloy tool steel (GB 1299-85) (2)

Alloy tool steels (GB 1299-85)

Alloy tool steel is an important industrial material that is widely used in the production and processing of various cutting tools, forming tools and measuring tools. GB 1299-85 is Chinas national standard on alloy tool steels and specifies its chemical composition, mechanical properties, heat treatment processes and tests.

1. Chemical composition

According to GB 1299-85, the chemical composition of alloy tool steel consists of carbon, manganese, silicon, vanadium, molybdenum, chromium, tungsten, nickel, phosphorus and sulfur. The elements in the main ingredients are determined and specified according to the types of each steel.

2. Mechanical Properties

The mechanical properties of alloy tool steel are determined by its tensile strength, yield strength, elongation, hardness and impact toughness. According to GB 1299-85, the permissible tensile strength range of steel of different types is different. Generally, the higher the carbon content, the higher the tensile strength and yield strength.

3. Heat Treatment Processes

The heat treatment processes of alloy tool steel include annealing, normalizing, quenching and tempering. All these processes can increase the strength, toughness and wear-resistance of alloy tool steel.

Annealing: Annealing is used to reduce hardness and increase toughness, and can be divided into two types: full annealing and diffuse annealing. The full annealing process is used to obtain an appropriate structure and properties.

Normalizing: Normalizing is used to reduce the hardness of the alloy tool steel, and can obtain a uniform structure.

Quenching: This process is used to obtain a higher strength and hardenability of alloy tool steel, which is a lot higher than that of normalizing.

Tempering: Tempering is used after quenching to reduce the hardness and strength of alloy tool steel and obtain the desired properties.

4. Tests

The tests for alloy tool steel are used to determine the quality of the steel and include hardness, impact, tensile and microstructural tests.

The hardness test is used to determine the hardness of the steel. The impact test is used to determine the impact strength of the steel. The tensile test is used to determine the tensile strength, yield strength, and elongation of the steel. The microstructural test is used to determine the microstructure of the steel.

Alloy tool steels are widely used in various industries and are essential industrial materials. GB 1299-85 is a national standard for the manufacture of these steels, and specifies its chemical composition, mechanical properties, heat treatment processes and tests.

Alloy Tool Steel (GB 1299-85)

Alloy tool steel is one of the important varieties of steel in China. With the development and progress of science and technology, the application of alloy tool steel is becoming more and more extensive, and its performance requirements are also becoming more and more strict. According to the state GB 1299-85 regulation, there are 5 major alloy tool steels: high speed steel (HSS), medium-temperature alloy steel (MTA), low-temperature alloy steel (LTA), stainless steel (SS), and wear-resistant alloy steel (WRS).

The high-speed steels, HSS, belong to hot-rolled alloy tool steels, and their hardness reaches HRC62-64 or even higher. HSS is widely used for cutting and milling tools on general-purpose machines and for cutting tools on high-speed and super-high-speed machines.

Medium temperature alloy tool steel (MTA) is a type of heat-treated alloyed tool steel with wear resistance and toughness that is suitable for medium to high temperature applications. The hardness of MTA reaches 50-62 HRC and its typical use is for die-forming tools such as cold-forming dies, extrusion dies and hot-press molds.

Low temperature alloy tool steel (LTA) is a type of heat-treated alloyed tool steel with relatively low hardness that is suitable for low temperature applications. The hardness of LTA reaches 40-50 HRC and its typical use is for cold working tools such as cold heading dies, punches and small molds.

Stainless steel (SS) is a type of alloy tool steel that is corrosion-resistant and heat-resistant. It has good weldability and low-temperature toughness. The hardness of SS reaches 40~50HRC and its typical applications are in marine environments, chemical processing and food processing.

Wear-resistant alloy steel (WRS) is a type of alloy tool steel that is wear-resistant and heat-resistant. Its hardness reaches 50-63HRC and its typical use is for die molds and tools used in rough environments such as abrasion and erosion.

In conclusion, alloy tool steel is a prevalent type of steel used in a wide variety of manufacturing applications. Its performance is characterized by wear resistance, toughness and hardness varying from type to type. With the guidance and regulation of GB 1299-85, alloy tool steel is increasingly playing a significant role in China’s industrialized production.