Super-thick hot-rolled high-alloy hot-work die steel and preparation method thereof

Abstract

The invention provides a super-thick hot-rolled high-alloy hot-work die steel and a preparation method thereof. The die steel comprises the following components of, in percentage by weight, 0.24%-0.30% of C, 0.36%-0.40% of Si, less than or equal to 0.010% of P, less than or equal to 0.005% of S, 0.45%-0.55% of Mn, 0.90%-1.20% of Cr, 0.55%-0.95% of Ni, 0.50%-1.00% of Cu, 0.30%-0.50% of W, 0.015%-0.030% of Als, 0.0005%-0.0035% of B, and the balance Fe and inevitable impurities. The preparation method comprises the following steps of smelting, large slab continuous casting, blank pretreatment, vacuum assembly, welding seam local modification, reheating, high-direction module rolling, module post-treatment and heat treatment. The hot-work die steel produced by the method has high polishing degree, high internal quality and high-direction performance.

Description

technical field [0001] The invention belongs to the technical field of metal material production, in particular to a method for preparing an extra-thick hot-rolled high-alloy hot work die steel. Background technique [0002] The future trend of the mold manufacturing industry is to develop in the direction of large-scale, precision, long life, and high efficiency. The development of more new production models and mold steels with excellent performance, more efficient, and greener short processes will become an important research direction in the future. . [0003] The mold industry is called the mother of the manufacturing industry. It can be said that the improvement of the manufacturing level is closely related to the quality and technological innovation of the mold steel. Countries around the world mainly adopt three methods to improve the quality of die steel, one is to optimize the composition of die steel and develop new steel types, the other is to improve the produc...

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Problems solved by technology

[0005] The patent application number 201510789402.9 is a production method of extra-thick carbon mold steel plate, which adopts a more pure and more regular continuous casting billet. This method is used to produce 45#, 50 with a carbon content of about 0.4-0.5%. #Steel, unable to meet the billet assembly of high-alloy products

The patent application number 201210264180.5 is a production method of steel plates for 150-400mm plastic molds. It introduces a composite billet and a combination of multiple welding methods. The process is complicated, but it still cannot meet the needs of molds with higher carbon and higher alloys. Steel billets

[0006] The patent of application number 201711079372.8 is a 200-350mm thick and high flaw detection requirement medium carbon alloy mold steel plate and its manufacturing method. It adopts composite blanking but does not provide a composite process, and the manufacturing method is similar to 201210264180.5. It is only applicable to the above-mentioned medium carbon Alloy steel, and the heating and compounding method adopted can easily cause the billet to oxidize, which is unfavorable for mold products that require high homogeneity

[0007] In addition, the above-mentioned patents all need to optimize the blank and increase the compression ratio to improve the flaw detection quality of the product, but on the one hand, this method is not easy to implement for continuous production, because the blank used for compounding often has a large unit weight. However, the internal quality of continuous casting slabs varies greatly at different continuous casting stages. In addition, the steel plate produced with a compression ratio of more than three times can only reach the level of φ3mm in flaw detection, which is far from enough for precision molds and can only be used for general mold bases. processing, and there is a risk of defects such as trachoma

In addition, for materials with high isotropic requirements, there is no solution using composite technology

[0008] The patent of application number 201711299296.1 is a method for continuous casting slab forging to produce high-quality plastic mold steel forgings. The production method of plastic extra-thick mold steel is carried out by 400mm continuous casting slab forging, but for higher alloy precision mold steel continuous Casting - production, and the lack of solutions for the production of continuous cast slabs with high isotropic properties

[0009] To sum up, in the face of the development of large-scale precision die steel, the cost of the existing process is extremely high. The above-mentioned problems can be solved by using the continuous casting process, but the development of large slabs is limited due to the characteristics of high-carbon and high-alloy materials.

In addition, die steels at home and abroad generally have problems such as high cost, long process, and complicated processes, and are affected by the original solidification structure such as die casting materials, resulting in poor performance reliability and stability. There is no good solution. In addition, the internal quality of the existing composite mold can only reach the level of φ3mm, which is far from the requirements of precision molds. For the extra-thick and high-alloy products produced by composite blanks, there is currently no high-grade material. Technical solutions

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