SU1682210A1 - Method of manufacture of hollow articles with inner relief - Google Patents

Abstract

The invention relates to the field of metal forming, in particular, to methods for producing hollow parts with relief. The purpose of the invention is to improve the quality of products obtained from steel with metastable austenite. When the core of the assembled set, consisting of a hollow billet and a shaping core having a shape memory effect, is heated, the design of the relief surface of the part is regulated. 4 ill., 1 tabl

Description

The invention relates to metallurgy, in particular to the processing of metals by pressure, and can be used in the manufacture of hollow products with a relief on the inner surface of steel or alloys with metastable austenite with a regulated level of mechanical properties.

The aim of the invention is to improve the quality of steel products with metastable austenite.

FIG. 1 shows a device j for implementing the proposed method in the initial position; in fig. 2 is a section of Al on FIG. one; in fig. 3 shows a device for implementing the method in the final position; in fig. 4 is a section BB in FIG. 3

The method is carried out as follows.

The core 1 (Fig. 1), which has a memory effect of a grinder, is preliminarily deformed at a temperature corresponding to an intezap4 development of martensitic transformation in steel under the influence of deformation, and the composition of the shape memory alloy is chosen so that deformation for steel was within the temperature range of the reverse martensitic transformation of the alloy and corresponded to the condition

Met "cp, gpn / cn" spl / / ln -An-i, s ... i, O / An-A /, (1J

where Mnst is the temperature of the onset of the martensitic transformation in steel;

Ansp / 1 and Akspl are the temperatures of the beginning and end of the reverse martensitic transformation in a shape memory alloy.

After that, the blank 2 is placed between the core 1 and the container 3 and the assembled set is heated to the deformation temperature of the blank material.

During the heating of the set to the temperature interval (1), the return deformation initiates martisite transformation of metastable austenite in steel. The deformation of the product in the specified temperature range causes C

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deformation of the martensite structure of deformation, which provides an increase in the complex mechanical properties of the deformed billet.

Example. The method was tested to deform the Fe-0.06C-14, 3Cr-7.6Ni-1, 6Mo maraging steel with metastable austenite. The core material used is an alloy TI-Nl-Fe, for which Anzpl -131 ° C, Axpl-60 ° C, the return deformation value from 10%. The temperature of the beginning of the martensitic transformation in steel is -70 ° C.

The preliminary deformation of the core is carried out by stretching at -196 ° C, i.e. at the temperature of the direct martensitic transformation; core diameter varies within (8.20 ± 0.05) (7.85 ± 0.05) mm, and a thermopress was collected at this temperature (Fig. 1)

The billet 2 is put on the core - a bushing with an inner diameter of 7.90 ± 0.005 mm and a wall thickness of 0.8 ± 0.005 mm and container 3, which prevents the relief being underdeveloped during stamping

During the heating of the heat press, the core 1 restores its original shape (as a result of martensitic transformation) and, by deforming the blank 2 and causing the transformation of a metastable austenite, creates a relief on its inner surface. The steel structure becomes fully martensitic.

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Mechanical properties of steel Fe-0, 06С-14. ZSg-7, bmy.bmo. deformed according to the conditions of the known and proposed methods are given in the table.

To release the preform, the press is cooled to -196 ° C, the core 1 is again stretched and the preform 2 is removed.

Claims (1)

Invention Formula The method of obtaining hollow articles with internal relief, which consists in pre-deforming the relief-forming core, having a shape memory effect, placing a hollow billet on it and then shaping it when the core is heated, in order to improve the quality of steel products with - with austable austenite, the deformation of the core is carried out at a temperature corresponding to the beginning of the direct martensitic transformation of its material under the influence of deformation, while as a mat The rial of the core uses an alloy with a temperature interval of the reverse martensitic transformation, covering the optimum temperature for deforming the material of the workpiece, determined from the condition Mnst Ansl-0,5 ... 0.8 / Anspl-Akspl /, where Mnst is the temperature of the martensitic transformation in steel; Anspl and Akspl, respectively, the temperatures of the beginning and end of the reverse martensitic transformation in an alloy with a shape memory effect. g 3 i 1 Aa FIG. 2 Fy