High-thermal-stability die-casting die steel and preparation method thereof

Abstract

The invention relates to the field of alloy steel manufacture, in particular to a high-thermal-stability die-casting die steel and a preparation and thermal treatment method thereof. The die-casting die steel is prepared from, by mass, 0.3-0.45% of C, 0.2-0.5% of Si, 0.30-0.60% of Mn, 2.00-4.00% of Cr, 1.80-3.00% of Mo, 0.40-0.80% of V, smaller than or equal to 0.005% of S, smaller than or equal to 0.02% of P and the balance Fe. The preparation method of the die-casting die steel comprises the steps of preparation, smelting, casting, electro slag remelting, high-temperature homogenization, forging, solid solution, balling, and quenching and tempering thermal treatment. Compared with common die-casting die steel of H13(4Cr5MoSiV1), DIEVAR(4Dr5Mo2V) and QRO90(4Cr3Mo2V1), the high toughness ratio of the die-casting die steel is guaranteed, and the die-casting die steel has superior thermal stability.

Description

technical field [0001] The invention belongs to the technical field of alloy steel manufacturing technology, and in particular relates to a die-casting die steel with high thermal stability and a preparation method thereof. Background technique [0002] In recent years, with the development of my country's automobile and other manufacturing products, the die steel industry has occupied an important position in my country, especially in the research of hot die casting die steel has made great progress. However, because the die-casting mold will be subjected to alternating cold and heat and continuous impact loads when it is in service, it will cause a lot of thermal damage, including thermal fatigue, thermal wear, and failures such as cracking, which will reduce the service life of the hot-working mold and cause economic losses. Therefore, it is required Hot work die casting die steel has strong red hardness, high temperature heat strength and good thermal stability. [0003...

AI Technical Summary

Problems solved by technology

However, because the die-casting mold will be subjected to alternating cold and heat and continuous impact loads when it is in service, it will cause a lot of thermal damage, including thermal fatigue, thermal wear, and failures such as cracking, which will reduce the service life of the hot-working mold and cause economic losses. Therefore, it is required Hot work die-casting die steel has strong red hardness, high temperature heat strength and good thermal stability, etc.

[0003] Traditional commonly used die-casting mold materials mainly include H series such as H13 (4Cr5MoSiV1), H11 (4Cr5MoSiV) steel grades with uniform carbides, good hardenability and high toughness, but poor temper softening resistance and high temperature heat strength. Insufficient and cannot meet the requirements of service under high temperature conditions; the new hot work die steel DIEVAR (4Cr5Mo2V) introduced by the Swedish Uddholm company through new technology and refining technology, while reducing the C and Si elements and increasing the content of the alloying element Mo, the steel is relatively Yu H13 has good wear resistance and cold and heat fatigue resistance, but when the temperature is higher than 620°C, its thermal fatigue performance will decrease significantly

[0004] The QRO series steel containing 3.0% Cr is a new type of die steel developed in Sweden, and has been widely used in the die industry, mainly represented by QRO45, QRO80, and QRO90. Considering that the Cr content in H13 steel is about 5%, due to Cr The ability to combine with carbon is strong, and the higher Cr content in the steel tends to form more M23C6 during tempering, which makes this type of carbide not only lower in hardness, but also easy to coarsen during the heat preservation process, making die steel reduced thermal stability

Although the binding force between V and C is stronger than that of Cr, and the carbides of V have higher resistance to temper softening, but the high content of Cr will hinder the precipitation and transformation of VC

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