SU1740481A1 - Powder material on ferrous base for caked articles production - Google Patents

Abstract

The invention relates to powder metallurgy, in particular to an iron-based powder material for the production of sintered articles. SUMMARY OF THE INVENTION: The iron-based powder material for producing sintered products containing carbon, silicon, manganese, and nitrogen contains components in the following ratio, wt%: carbon 0.001-0.05; silicon 0.6-0.9; manganese 0.3-0.45; nitrogen 0.003-0.005; iron is the rest, when the ratio of the content of silicon and manganese is 2-2.5. The oxygen content in the material decreases 3-4 times, and the strength of the sintered products increases from 285 to 330-360 MPa. 2 tab.

Description

The invention relates to powder metallurgy, in particular to the production of iron-based powders intended for the manufacture of extrusion and sintering products.

Among low-alloyed steel powders with high formability and compressibility, powder of composition is known, wt.%: Carbon is not more than 0.02; manganese 0.3-2.0; chromium 0.1-2.0; vanadium 0.03-0.5; niobium 0.05-0.5; Nickel 0.1-2.0; copper 0.2-2.0; iron else. However, the quality of the products of this material is lowered due to the presence of 0.20-0.35% by weight of oxygen in the powder, which transforms into powder particles during their cooling after spraying the melt.

Closest to the invention is powdered low alloy steel containing, in wt.%:

Less than 0.05 1.0-2.4 0.2-0.7 Less than 0.1 0.015 metals from the group

Carbon

Nickel

Copper

Silicon

Nitrogen

and one or more wt.%:

Manganese 0.1-0.5.

Chrome 0.1-0.7

Molybdenum 0,1-0,8

A disadvantage of the known iron-based powder material is a decrease in the strength of the sintered billet as a result of an increase in the oxygen content of the starting powder during the cooling process after spraying the melt. Thus, the tensile strength of sintered billets with an oxygen concentration of 0.057 wt.% Is 350 MPa, and at 0.415 wt.% Of oxygen, only 280 MPa.

ABOUT

oo

The aim of the invention is to increase the resistance of the material to oxidation and the strength of sintered products.

This goal is achieved by maintaining in the powder composition the ratio of the amount of silicon to manganese equal to 2.0-2.5 with the following content of components, wt.%:

Carbon0,001-0,050

Silicon 0.60-0.90

Manganese0.30-0.45

Nitro0,003-0,005

IronErest

The proposed composition was developed on the basis of the established dependence of the rate of high-temperature oxidation of the iron-based alloy on the ratio of silicon and manganese (some data are given in Table 1).

It can be seen that the oxidation rate of the iron-based alloy decreases with an increase in the ratio of silicon and manganese included in the composition of the alloy. At the same time, there is no need to use expensive, complicating processes of smelting and sputtering of elements that are known to make steel scaling, such as nickel, chromium, aluminum, titanium. In addition, when the listed alloying elements are present in the powder, its compressibility is impaired.

When the ratio of the silicon content in the material to the manganese content is more than 2.5, the melt viscosity increases and the process of its spraying becomes more complex.

For experimental verification of this composition 6 alloys were melted (see Table 2). The fusion of the pure components was carried out in an atmosphere of gels in corundum crucibles at 1880-1910 K for 40 minutes. The resulting alloys were sprayed in an atmosphere of gels in a laboratory electric pulse grinding unit, followed by cooling in water. After

extracting from water and drying, the powder was pressed (pressure 700-750 MPa, speed 2 mm / min) and sintered in an atmosphere of 80% gels and 20% hydrogen at 1380-1420 K for

half an hour. Pressing and sintering operations were repeated twice. The obtained blanks were tested for stretching on the UMM-5 machine according to the standard procedure.

The data presented confirm that the samples of the proposed composition with the specified ratio of silicon and manganese (NsNs 1, 2 and 3) contain a reduced amount of oxygen and have greater strength as compared to the prototype

(Kb 6), as well as with materials in which the content of components is beyond the limits of the application (Ns 4 and 5). Moreover, the magnitude of the oo increases from 285 (prototype) to 330-360 MPa (the claimed composition), or

15.8-26.3%, i.e. the reliability of products from low-alloyed iron-based powder material is improved, the economy is nickel, copper, chromium, molybdenum. In addition, the product of the powder of this composition in

less susceptible to corrosion during their operation.

Claims (1)

An iron-based powder material for obtaining sintered products containing carbon, silicon, manganese and nitrogen, characterized in that, in order to increase the oxidative stability of the material and the strength of the sintered products, it contains components in the following ratio, wt.%: Carbon0,001-0,05 Silicon0,6-0,9 Manganese 0.3-0.45 Nitro0,003-0,005 IronErest when the ratio of silicon to manganese is 2.0-2.5. The average specific strength of the oxidation of iron-carbon alloys at 10-73KV weakly oxidizing atmosphere for 2.5 hours Table 1 Chemical composition of powders and test results table 2