Due to the development and improvement of the output and technical level of China’s iron and steel industry, the demand and standards in the steel market are also improving, which makes some high-quality iron and steel materials come into being. Compared with other materials, iron and steel materials are rich in resources. Because of their simple production and processing and controllable cost and performance, iron and steel materials are difficult to replace. In the development of economy and society, the needs of “good performance, low cost, easy processing, high precision and green” are put forward. It is urgent to develop advanced steel to meet the above needs.
Stainless steel usually refers to alloy steel with Cr content greater than 11.7% or Ni content greater than 8%. 2Crl3 is a typical martensitic stainless steel. Generally, martensitic stainless steel is used in the form of martensitic structure. According to different grades of steel and different mechanical property requirements, appropriate process specifications can be selected. Only after a suitable series of heat treatment can the required microstructure and properties be obtained. Under the heat treatment system, the classical process method based on quenching and tempering is also an important strengthening and initial means of martensitic stainless steel. After consulting relevant data, the appropriate quenching temperature should be selected according to the size and shape of parts and combined with the equipment conditions.
2Crl3 stainless steel has the advantages of strong corrosion resistance, excellent shock absorption and good hardenability. It is used in many aspects such as medical treatment, locomotive and military industry, which makes high-quality 2Crl3 steel a hot spot, and 2013 with high strength and super toughness has become a need and guarantee. However, the carbon content in 2013 is low. If you want to achieve good performance parameters, in addition to qualified chemical composition, you must also carry out appropriate heat treatment to obtain stable, fine and uniform structure. The strengthening process is mostly quenching and tempering treatment. First, quenching is carried out to obtain martensitic structure with high hardness, and then high-temperature tempering is carried out, The goal is to obtain fine tempered sorbite phase. Due to the change of microstructure after the influence of material itself and heat treatment temperature, the high-temperature quenched structure obtains martensite and avoids insoluble ferrite. Although the strength and hardness will become very high, if the heating temperature is too high, the microstructure phase is single and the size is coarse, the initial properties of steel will be affected, In order to obtain the characteristics of strengthening and toughening with good hardness and toughness, sub temperature quenching process is usually used, which is a new strengthening and primary heat treatment process.
The traditional heat treatment method of 2Crl3 generally recommends 1000 ° c-1050 ° C oil cooling or water cooling + 660 ° c-770 ° C oil cooling, water cooling or air cooling. Practice shows that too high AC3 point will lead to coarse grains of martensite structure and reduce the strength and initial properties of the material. When the temperature reaches 105ctc, quenching has little effect on strengthening and toughening. The hardness is basically unchanged and the toughness decreases. Although martensite is obtained by complete quenching to avoid insoluble ferrite, Thus, the strength and hardness are improved, but once the heating temperature is too high, the continuous growth and extension of grains leads to the coarse and uneven structure, which still has a bad impact on the demand for strengthening and toughening. The quenched martensite is “hard and brittle” and is difficult to be machined. Therefore, tempering is continued to improve the plastic toughness and machinability. Generally, tempering is carried out at 200 ° C-700 ° C. The microstructure and grain condition of 2Crl3 stainless steel after quenching and tempering determines its performance. However, heat treatment determines the microstructure type and grain size.