SU1247163A1 - Method of producing sintered articles - Google Patents

Description

The invention relates to powder metallurgy, in particular, to methods for making sintered articles by hot isostatic pressing and powder material.

The purpose of the invention is the expansion of technological capabilities by obtaining high-quality bimetallic products and increasing the productivity of the process. I

FIG. Figure 1 shows the temperature distribution over the section of the compact when the HDF container is heated; in fig. 2 - the same, with. simultaneous heating of the HDC container and the core. According to FIG. 1, the heating of the core 1 occurs through the layer of the powder material 2 when the high-frequency filter of the container 3 is heated, surrounded by loose thermal insulation 4 and an airtight elastic shell 5 placed in the indicator 6.

FIG. 1 The following notation is used: T, T, Tjn, Tsts. - intermediate temperatures in the process of heating the high-frequency hermetic shell, metal container, surface and center of the core, respectively; t, t,, final temperatures in the process of heating the high-frequency metal container, the surface and center of the core, respectively; dTm is the temperature gradient in the powder layer at the end of heating. According to FIG. The heating of the metallic powder layer, which does not heat up from the alternating magnetic polarizer, is carried out by applying heat from both the core side and the container side.

FIG. 2 Accept the following notation: T,, And, T.r || , Tsts- intermediate temperatures of the hermetic shell, metal container, surface and center of the core, respectively, while heating; TD, T, T | 1, the final temperatures of the hermetic shell, metal container, surface and center of the core, respectively, while heating AT, is the temperature gradient in the powder layer at the end of heating.

The depth of penetration of the current into the hot container material is selected from the relationship:

VOP (. T

1 -G

where p is the electrical resistance of the container material, f is the frequency of the inductor current. Example. Core and 160 mm

has a wall thickness of 6 mm, which is 0.3 times the depth of current penetration into the hot material of the container.

Current penetration depth (i-oo) into hot material at current frequency.

1000 Hz generator with a power of 150 kW is 18 mm (for material St1-StZ, temperature 1150 C).

 After installing the core in the container, the powder was poured and closed

5 container lid. After that, the container with the core and the powder placed in it was placed in an electric hermetic enclosure with a heat-insulating medium 150 mm thick

0 with its vacuuming. The elastic shell with the heat-insulating medium and the container was transferred to the inductor and at the same time the HDTV container and the core with

5 by simultaneous vacuuming of the hermetic shell and its cooling (for example, water). Then, isostatic pressing was carried out in an isostat at a pressure of 1000-1100 kg / cm.

The table shows data on the heating speeds of TBCh compacts with a 200 mm container of StZ steel, a core of 150-160 mm of K 1Sh steel at a current frequency of 1000 Hz, as well as temperatures gradients in the powder layer and the presence of delaminations of the pressed layer from the core surface depending on the ratio of the thickness-) НЫ of the wall (S) of the container and the depth

Q penetration (AGOR) into the hot metal container.

It follows from the table that high-quality pressing of the powder layer made of high-speed steels corresponds to a wall thickness of 0.2-0.5 of the depth of current penetration into the hot metal of the container, i.e. optimal distribution of heating energy between the container and the core while simultaneously heating the HDTV. Thus, the proposed method allows to obtain high quality bimetallic billets of any size, eliminating the use of an intermediate layer of powder of the core material. At the same time, the heating rate is reduced by 2-4 times, which significantly increases the productivity of the process.

0

five

five

50

0.1

0.2

Warm-up time of the layer of powder and core to 1150 С, h

Temperature gradient in the powder layer after 2 h of high-frequency heating, С

The detachment of the powder layer from the surface of the core

2,32,12,02,0 2,1 2,52,8-3 3-3,5

60-70 20-25 15-20 15-20 25 30-4550-70 100-200

Yes No No No No Yes Yes Yes

0.4

0.5

0.6

0.7

0.8

Editor A. Ogar

Compiled by T, Sheveleva Tehred I.Popovich

Order 4054/13 Circulation 757 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, Projecto st., 4

FIG. 2

Proofreader S. Shekmar

Claims (1)

METHOD FOR PRODUCING SINTERED PRODUCTS, including loading the container with the material of the obtained product, placing the container in an airtight shell with heat insulation / = (0.2-0.5) 4 _Г0Р , where δ _mountains is the depth of current penetration into the hot material of the container. <put.1 • 1247163