DE1810883C3 - Process for the production of molded parts with high density - Google Patents

Description

From the German patent specification 889 454 is already a method for producing. Sintered steel

The following is the method according to the invention

bodies known which are pre-sintered at temperatures between 700 ° C and 1000 ° C using exemplary embodiments and at temperatures between
see 1200 and 1300 ^c C are fully sintered. the

Sintered steel bodies mainly consist of example 1

Iron powder with additives of carbon, graphite and possibly alloy elements. With the known In each case, sintering takes place in the process.

It has already been proposed that pre-pressed bodies consisting predominantly of iron powder be increased to 800 to HOO ⁰ C without sintering

50 / -> / 0 From a powder hybrid of electrolytic iron with "chromium, 59% nickel and 26% molybdenum was under a pressure of 6 t / cm ^2, a compact forth provided, this is heated to 85O ° C and in an at 35O ⁰ C preheated and held tool with

heat and press in a preheated to 300 to 350 ° C, 25 a pressure of 8 t / cm ² . The mold part, kept at a constant temperature, had a density of after this treatment

8.51 g / cm ³ . The molded part was then ^{annealed for 4 hours at 1250 °} C. in a vacuum. After the annealing, the molding had a tensile strength of

to repress. Such iron moldings are characterized by a comparatively high density of 7.4 to 7.8 g / cm ³ . It is essential that the production of such high-density parts from a pre-30 48 kp / mm ^s .

pressed bodies without the usual time-dependent sintering Example 2

takes place, namely by simply heating the pre-pressing

body to 800 to 1100 ° C and subsequent post-From a powder mixture of electrolyte iron with

pressing the same in a tool pre-heated to 300 to 350 ° C, 16 ° / ₀ chromium, 57% nickel, 17 ° / ₀ molybdenum and 4% heated tool, the gradient between the 35 ^{° tungsten with a pressure of 6 t / cm 2} a tool and the pressed body temperature about kon- pressed body produced. This was still vorstant to 850 ⁰ C. The constant temperature relationship between the pressed body and the tool during repressing always leads to the same recrystallization conditions.

and heated in a 35O ⁰ C to the preheated and held tool with a molding pressure of 8 t / cm ² coined warm. After glowing for ^ '/ j hours at

especially in mass production 40 1250 ⁰ C in a vacuum, the body had a density of

have a decisive effect, in which the pre-compression in -sin and the same tool is redensified in rapid succession will.

It has now emerged that what was mentioned in the introduction Process for the production of molded parts of high density not only for the most part made of iron powder moldings, but also in an excellent manner for moldings made of not or alloys that are difficult to forgive

45 8.78 g / cm ³ , a tensile strength of 39 kp / mm ² , an elongation at break of 6.4% and a Brinell hardness of 120.

Example 3

From a powder mixture of electrolytic iron with 1% chromium, 65% nickel and 30% molybdenum * a compact was produced at a pressure of (3 t / cm, heated to 85O ° C and in a 350 ³ C

and even at a low mold temperature 50 preheated and held mold under one

let carry out. It is therefore in accordance with the invention suggested for the pre-press body a made of hochlcgierlen, to use non-forgeable or difficult to forgive materials The temperature of the work is increased to 150 to 35O ° C - 55 4%.

to deliver.

The molding, which has been pre-pressed in a known manner with a pressure of about 6 l / cm ^{1, is re} -pressed under a pressure of 8 t / cm ³ .

Pressing pressure of 8 t / cm * re-pressed. After annealing for 4 1/2 hours at 1250 ° C. in vacuo, the pressed body had a tensile strength of 57 kp / mm * and an elongation at break of ^{8.35 g / cm 3}

Example 4

Made from a powder mix of 20% fine-grained Chromium, 79% carbonyl nickel and 1% titanium carbide

The Aufrcchlerhallung the preheating temperature of the 60 was produced with a pressing pressure of 6 t / cm * a pressing tool during the post-pressing is carried out by body. This was then heated to 850 ° C. and held in a tool preheated to 350 ° C. with a pressure of 8 t / cm ¹

regulated cooling.

The procedure according to the application provides to a certain extent a "powder forging" that in comparison

In relation to the conventional forging processes, for example 65,150 ° C. in a vacuum, the pressed body had a density, as in the die forging, tiic production of 7.6 g / cin ¹ . Its tensile strength was 30 moldings made of either impossible or difficult to forge
Factory si open with good \ esligkeitseigenschaflen enable

na '-. pressed. After a 4 ^I / _J annealing at stündigcn

kp / mm ¹ , its elongation at break 16.5% and its Brinell hardness 105.

Claims (2)

i 810 883 Patent claims: ! A process for the production of high-density sun f-'ormteile by recompaction or re- (οτίΐζΓι ch.Ci. crhi.'zten pre-price grains in a »preheated tool, characterized in that a powder mixture consisting of high-alloyed, non-malleable or difficult to forge meiaücn according to the Press without sintering on HOO his! HX) ³ C he him and in a preheated to IMt to 350'C, while de-. N.iehpre «-: ens at constant temperature tapped tool n.icligepreOt vvirJ. 2. The method according to claim 1, characterized in that the repressing is about 4 to 5 hours annealing of the molded part * at! 250 C connects in a vacuum.