Method for producing hot-forming part with variable strength and lower die base of die

Abstract

The invention relates to the field of hot forming, and discloses a method for producing a hot-forming part with variable strength and a lower die base of a die. The method comprises the steps that a plate material which is fully austenitized is put into the die for producing the hot-forming part to be stamped; in the stamping process, the area, needing to be machined to be in high strength, of the plate material is rapidly cooled to the temperature less than T<3> DEG C under the condition that the cooling rate V<1> is larger than the critical quenching rate V of the plate material, and the high strength area only provided with martensite microstructures is obtained; the area, needing to be machined to be in low strength, of the plate material is cooled to be within the preset temperature ranging from T<4> DEG C to T<5> DEG C under the condition that the cooling rate V<2> is smaller than V, and the low strength area which is simultaneously provided with austenite, bainite and / or pearlite microstructures is obtained; after the pressure is kept for a preset time period t<2>, stamping is completed, and the hot forming part with the variable strength is obtained. Compared with the prior art, according to the method for producing the hot-forming part with the variable strength and the lower die base of the die, the temperature control over the areas with different strength requirements in the part is flexible and effective, a transition area is narrow, and the situation of scrapping of the part can be avoided as much as possible.

Description

technical field [0001] The invention relates to the field of thermoforming, in particular to a method for producing variable-strength thermoforming parts and a lower mold seat of a mould. Background technique [0002] Variable strength thermoformed parts refer to the existence of different strength regions in the same thermoformed part. For example, in some auto parts, it is hoped that in the same part, the tensile strength of some areas is greater than 1300MPa to achieve ultra-high strength; while the strength of another part of the area is less than 800MPa to achieve local area strength weakening, thereby achieving impact collapse and absorption impact energy. [0003] At present, a boron steel with a brand name of 22MnB5 is usually used as the raw material for hot forming production, with a tensile strength of about 600MPa and a microstructure of ferrite-pearlite. like figure 1 As shown, during production, the coiled material of the raw material is first punched out to...

AI Technical Summary

Problems solved by technology

Considering factors such as sheet heating, sheet transfer, stamping quenching and other factors in the thermoforming production process, and the cooling rate of the red-heated sheet raw material is about 10-15°C / S when exposed to the air, the temperature of the sheet raw material exposed to the air Uniform cooling during the process and the expected material properties cannot be obtained

[0006] Although there are many methods to control the cooling rate of the local area of ​​the sheet material, most of them cannot be accurately controlled and the effect is not good.

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