Hot stamping die steel and production method thereof

Abstract

The invention provides hot stamping die steel and a production method thereof. The hot stamping die steel is composed of, by weight, 0.45-0.50% of C, 0.1-0.3% of Si, 0.1-0.3% of Mn, 2.0-2.3% of Cr, 2.3-2.5% of Mo, 0.8-1.0% of V, smaller than or equal to 0.03% of P, smaller than or equal to 0.03% of S and the balance Fe and other inevitable impurities and meets the relational expressions that Mo / Cr=1-1.25 and V / Cr=0.35-0.43. By means of the electroslag remelting process, the ultrafine thermal treatment process, the vacuum thermal treatment process and the plasma nitriding surface treatment process, the produced and obtained hot stamping die steel is low in cost and high in comprehensive performance; the hot stamping die steel has a thermal conductivity coefficient of 34.3 W / m.k, quenching and tempering hardness of 50-53 HRC, ballistic work of 180-210 J, surface hardness of 850-1040 HV0.3 and diffusion thickness of 230-300 microns, and a white bright layer is ceaseless after nitriding.

Description

technical field [0001] The invention relates to the field of die steel manufacturing, in particular to a hot stamping die steel and a production method thereof. Background technique [0002] Die steel is usually divided into three categories according to the object of mold use: cold work die steel, hot work die steel and plastic mold steel. Hot stamping die steel belongs to hot work die steel. Hot stamping die steel is one of the die steels whose usage has increased sharply and consumed the most in recent decades. Its working conditions are more complicated than general hot work die steel. [0003] With the rapid development of the automobile industry and the continuous improvement of the demand for lightweight automobiles, the hot stamping forming process is mainly used to obtain stamping parts with ultra-high strength. When obtaining ultra-high-strength steel, due to the extremely high forming force required by the cold stamping forming process, it is easy to cause mold d...

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Problems solved by technology

[0008] Chinese patent CN102586716 discloses a wear-resistant cermet coating and its preparation method for surface strengthening of hot work die steel. The cermet coating and the substrate are all different materials, and there is an obvious interface between the substrate material and the coating It is not a good metallurgical combination; Chinese patent CN102650029 also discloses a method for preparing a nano-ceramic composite coating material on the surface of hot-work die steel, and the nano-scale Al 2 o 3 、TiO 2 The slurry is granulated by liquid phase spraying, and after the powder is sintered, the spray feed material of 40 μm to 60 μm is screened out; the nickel-clad aluminum coating is directly sprayed on the pretreated substrate sample by plasma spraying, and finally the prepared transition The Al2O3 / TiO2 nano-ceramic composite coating is prepared by plasma spraying on the layer, which can improve the microhardness and wear resistance of the mold surface. However, the coating technology is very complicated and requires high cleanliness of the mold surface. For small batches Die use is acceptable, not suitable for a large number of industrial applications

Its main advantages are that the hot work mold can obtain high hardness and excellent wear resistance, low boronizing temperature, small deformation of the workpiece, fast boronizing speed, controllable boronizing layer, and improved thermal fatigue performance, which is environmentally friendly. Contamination, no subsequent heat treatment is required, but the surface of the mold needs to be pre-surface nano-treated, that is, shot blasting treatment, which is not suitable for strengthening treatment of hot stamping molds

[0011] Chinese patent CN101928912 discloses a low-temperature carburizing method for hot work die steel, through the diffusion of active atoms, reacting with the matrix material to form a gradual compound or solid solution diffusion layer, the carburized workpiece after quenching and tempering needs post-treatment, and carburizing Processing includes a very complex quenching and tempering process, and the tempering temperature is higher, resulting in a lower hardness of the matrix

However, the use of ion implantation in molds has great limitations. It cannot handle the unevenness of complex shapes. The implanted layer is very thin and is generally measured in nanometers, and the maximum depth is only 0.1 μm. Moreover, whether it is ion implantation equipment or The cost of rare earth raw materials is very expensive, the process is difficult to control, and it is not suitable for large-scale production

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