SU773119A1 - Master alloy - Google Patents

Description

The invention relates to the field of ferrous metallurgy, in particular, to the change of high-performance ligatures and modifiers for the production of high-strength cast iron with an increased level of mechanical and operational properties.

Known ligature, which contains, wt%: magnesium 3-12, calcium 69, 5, silicon 2-15, iron 2-15, REM 10 1.5-6, carbon 0.15-0.45, aluminum the rest ( one .

The disadvantage of this ligature is the increased content of magnesium, calcium HI iron, which not only increases its cost, but also makes it difficult to produce high-strength cast iron.

Closest to the invention according to the technical essence and the achieved effect is a ligature of the following composition 2}, wt.%:

Magnesium 5-10

Calcium 3-20 25

Rare earth

yatally20-40

Aluminum0,1-10

Iron2-19

Silicon Else.

A significant disadvantage of such a ligature is that it does not provide an increase in the scaling resistance, high stability of high-strength cast iron, and the operational durability of the castings made from it.

These deficiencies are mainly due to the low content of aluminum. Therefore, treatment with this cast iron modifier does not provide it with the necessary aluminum content for scaling resistance, high stability, and other important properties. In a certain modifier, an increased amount of magnesium and calcium is contained in the modifier, which causes a significant pyroelectric effect and, in some cases, the release of metal, reduces the relative absorption of magnesium, leads to slagging and the appearance of more refractory slag. All of these factors make it extremely difficult to produce castings from nodular nodular cast iron. The high content of REN in the modifier significantly increases its cost.

The purpose of the invention is to increase the scale of resistance, high stability of cast iron and exploitation 7

Noah resistance made from it castings.

The goal is achieved by the fact that the proposed ligature contains xc components in the following ratio, wt.%:

Magnesium0.3-2.9

Calcium 0.01-2.9

REM0, OD-10

Aluminum 60-98

Silicon0,1-15

IronErest

The selected contents of magnesium, calcium and rare-earth metals in the proposed ligature are determined by the technological features of the production, scaled high-strength cast iron under production conditions and the following factors. Typically, cast iron is melted in cupolas and, during the casting process, the ladle is modified with modifiers or ligatures. The magnesium content in the ligature above the upper limit of -2.9% causes a pyro effect, accompanied by the release of a liquid metal. At the same time, the relative absorption of magnesium by cast iron is reduced. A lower magnesium content below the lower limit, 0.3%, does not ensure the formation of nodular graphite in the iron and, accordingly, its high properties. In relation to calcium, the main factor in its content above the upper limit of 2.9% is intensive slagging, accompanied by the formation of refractory slag. When it is contained in a ligature in an amount of 0.01 wt.% And more stable, its positive effect is manifested in the performance of the refining capacity of the ligature, as well as the improvement of the shape of graphite.

Similarly, calcium, when the content of rare-earth metals in a ligature of 0.01 wt4% and above, the latter begin to have a modifying effect on the cast iron and improve

in it is a form of graphite. However, when the content of rare-earth metals in ligature exceeds 10 weight in the processed iron due to an excessive amount of rare-earth metals, the tendency to chill increases, brittleness appears, the spheroidizing effect disappears.

The increase in the content of aluminum in the ligature, as compared with the known modifier, is due to the fact that the proposed ligature is intended for scale-resistant, life-resistant high-strength nodular nodular cast iron. In the process of modifying the cast iron when it is released from the furnace, by adjusting the amount of the ligature introduced and its aluminum content, it is possible to produce cast iron with different aluminum contents from 2 to 23%, for example No. 41-04Ш, ЖЧ1-02ХШ, ЖЧ10605, ЖЧ1-022Ш and others In this case, the optimum aluminum content is determined by the range of 60-98 wt.%. A lower content of it, below the lower limit, requires a significant amount of the ligature introduced into the cast iron, which reduces the temperature of the melt. More, above the upper limit is impractical because the content of calcium in calcium, magnesium and rare-earth metals decreases.

The silicon content in the proposed ligature should be in the range of 0.1-15 wt.%, Since its greater content (over 15 wt.%) In the treated iron appears an excess amount of silicon - over 2%, which is not allowed by GOST , and at less than 0.1 wt.% silicon, the ligature loses its processability

To determine the optimal composition of the proposed alloy, experimental melts of high-strength cast irons of the type KCH1-04Sh and ZHCH1-022Sh (chugal,

/ GOST 7763-76).

Experimental compositions of the ligatures are given in table. one.

Table 1

Known composition

10.3

6.2

18,223.4

Rest

The iron is smelted in an 8 t cupola. Equal addition of 6% of ligatures increases in heated to bOO-800 with a kae 11iveny Koaia. Such an additive in all variants modify 2 tons of liquid iron.

In the process of research, the scaling resistance, the growth resistance of the scaling resistance (weight gain of samples, g / m)

Rotational stability (thickness of the flange - casting, mm mm)

Operational stability of castings, months Note:

From the above results, it follows that the proposed master alloy of compositions No. 2-6 provides, in comparison with the known modifier, a significant increase in the whole complex: the studied properties. At the same time, when iBec samples on scintillability is reduced from 0.19 to 0.10. i.e. almost doubled. After 3 months of testing, the thickness of the flanges of castings modified with a ligature of compositions 2-6, from 40 mm increases by only 2-3 mm or remains constant.

Castings modified with a known modifier are intensely oxidized, have a flange thickness of 75 mm and are crushed during the 4th month of testing. This testifies to the high cost-effectiveness of castings modified with the proposed ligature.

High scale resistance and high durability of castings provide castings with a significant increase in operational durability. Thus, castings modified with a known modifier are destroyed in the fourth month of continuous round-the-clock tests, while castings modified by the proposed ligature of compounds 2-6 are idle without destroying more than 6 months of production.

Similar results were obtained with the additional tests of the testing and operational durability of cast iron castings modified by experimental compositions of ligatures.

The results of testing samples and castings on iron type ХЧ1-04Ш are given in table. 2

a b and c

ODO 0.12 0.12 0.11 0.16 0.15

42 48

40

47 48

45 58 61

other specimens and castings from another cast iron grade ЖЧ1-022Ш. Under the condition that the proposed ligature of compositions 2-6 is modified, the weight of the samples on the scale will be -. The resistance is 0.15-0.18 g / m L1, an increase in the size of the flanges of the castings is not observed after 6 months of trial, and their service life is increased by 1.5-2 times. When modifying with a known modifier, the scaling resistance is 0.22.

Thus, the proposed ligature is universal, since

5 makes it possible to produce cast irons with different aluminum contents and with a high level of metallic resistance and high stability. An increase in these properties ultimately provides a noticeable increase in the operational durability of the castings. The proposed ligature can be recommended for widespread use in the manufacture of castings of supports for boilers, lids, and other of them from 5 chemical instruments, as well as for chills, roller tables, roller table furnaces, etc. The increase in the service life of these castings by 1.5–2 times provides a noticeable increase in labor productivity by 5–6% due to a decrease in just one day per month. changeover time.

Claims (2)

1. USSR author's certificate No. 464645, cl. C 22 C 35/00, 1975. 2. USSR author's certificate number 490860, cl. C 22 C 35/00, 1975.