SU773116A1 - Modifier - Google Patents

Description

(5) MODIFIER

one

The invention relates to foundry, in particular, to the modification of cast iron with complex alloys.

Known modifier iron 5 of the following composition, wt.%:

Silicon 23-25

Iron -5-7

Aluminum Else

However, this modifier does not provide a high degree of graphitization of cast iron,

The closest to the offer in terms of composition and technical nature is modifier 2 of the following content: 15: tava, wt.%:

Silicon 10-16

Iron5-9

Aluminum Else

However, when using a given modifier composition for the processing of cast iron in the amount of 1-2%. From the consumption of liquid metal due to the high aluminum content in the cast iron microstructure, significant inclusions of cementite are observed, which leads to surface bleaching of castings and their deterioration. workability and reduction of physical and mechanical. properties of the metal, so danA is 30

By becoming more expedient to use for - castings, cooled at low speeds. In the production of thin-walled casting, this composition cannot ensure the production of castings without chill with high physicomechanical properties. In addition, the application of the known composition of the modifier does not lead to a noticeable improvement in the size and shape of graphite inclusions:

The purpose of the invention is the development of a modifier composition that provides a reduction in the size and improvement of the shape of graphite inclusions, the elimination of chill in thin-walled castings and the improvement of physical and mechanical properties.

The goal is achieved by the fact that the proposed modifier for cast iron additionally contains chromium and indium in the following ratio of components: weight:%:

Silicon 10-25

Iron10-15

Chrome 10-25

Indium 15-30

Aluminum Else

An increase in the composition of silicon and iron modifier up to 20-40% and an increase in the amount of aluminum carbide-forming element with an additional

the introduction of chromium and indium provides for obtaining thin-walled iron castings without chill and with high fizik-machianic properties.

The introduction of chromium and indium into the composition of the modifier allows grinding the grain, improves the shape of graphite inclusions, which positively affects both the increase in the mechanical properties of the iron and the decrease in its tendency to form and shrinkage, shrinkage porosity.

Indium in cast iron plays the role of a strong modifying element, while chromium plays the role of a perlite-stabilizing element.

The verification of the effectiveness of the modifier is carried out on base iron, containing, wt.% Jycarbon 3.5; silicon 1.6; manganese 0.5; sulfur O, 03; phosphorus 0.04; iron else.

The cast iron is melted in a 30 kg induction furnace. The temperature of the cast iron during the modification is in the range 13 ° -1380 ° C. The modification is carried out by immersing the modifier before the release of the cast iron to the bottom

The content in the silicon modifier in the range of 10-25% leads to the grinding of graphite, its uniform distribution, which contributes to the improvement of the mechanical properties of cast iron.

The iron content in the modifier is determined by the conditions for its smelting in industrial furnaces and the composition of the raw materials and, first of all, by the amount of ferroalloys in the mixture. The limits for iron content are established experimentally.

Example. In the laboratories and pilot production conditions, the modifier compositions given in Table 1 are manufactured and tested.

Table 1

Rest

bucket. The amount of modifier introduced is 1.5% by weight of the molten iron.

To study the structure and mechanical properties of cast iron modified with a known and proposed composition of 40, tretylate samples and samples with a diameter of 5.10 and 20 mm are poured.

In tab. 2 shows the mechanical properties and structure of the investigated

lk chugunov. „, -

5Table2.

The initial cast iron prior to the introduction of the modifier has a tensile strength of .18 kgf / mm, nipK bending strength 42 kgf / mm and a hardness of 180 HB.

The microstructure of cast iron, modified by the proposed modifier, in samples with a diameter of 5.10 and 20 mm is pearlitic with a content of up to 5% ferrite, there is no cementite in the structure.plate. In the cast irons of samples 5, 10 and 20 mm modified with a known modifier composition, there are inclusions of carbides up to 6% in the structure.

Verification of the proposed composition of the modifier shows its effectiveness in obtaining cast irons with enhanced physical and mechanical properties, pearlite structure and without bleaching9.

Claims (2)

1. Author's certificate of the USSR 422787, cl. C 22 C 35/00, 1972. 2. USSR author's certificate 0 No. 535368, class C 22 C 35/00, 1975.