SU1678890A1 - Wear resistant cast iron - Google Patents

Description

The invention relates to metallurgy, in particular, to the development of compositions of white wear-resistant cast irons, with increased microhardness of carbides for working under conditions of impact-abrasive wear.

The purpose of the invention is to increase the shock and abrasion resistance.

The content of the main components, wt.%: Carbon 2.58-2.76; silicon 0.51-0.88; Manganese 0.85-1.65 determined the basis of the practice of production of white cast irons for wear-resistant castings operating under shock loads. By reducing the carbon content (less than 2.58 wt.%) And silicon (less than 0.51 wt.%) And increasing the manganese concentration (more than 1.65 wt.%), Casting properties, impact strength, crack resistance, liquation increase and stability decrease. structures, impact-abrasive wear resistance, operational properties With a bopee carbon concentration of 2.76 wt.% silicon more than 0.88 May% and manganese less than 0.85

wt.% The structure in the castings becomes coarse, the microhardness of the carbides and the matrix, their wear resistance and the stability of the toughness and mechanical properties in the castings decrease, which reduces the performance properties.

The introduction of boron in the amount of 0.03-0.11% by weight of aluminum and in the amount of 0.006-0.03 wt.% Deoxidizes cast iron, crushes the structure, increases the crack resistance, hardness and wear resistance of the matrix, hardenability, microhardness of carbides, matrix stability in castings, what provides decrease in abrasive wear and increase in operational firmness and mechanical properties. The aluminum content is based on a concentration of 0.006 wt.%, And boron from 0.03 wt.%, When the grinding of the structure and an increase in hardness and wear resistance in castings are noted and limited to a concentration of 0.03 and 0.11 wt.%, Respectively, above which a decrease in the homogeneity of the structure and

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the appearance of nonmetallic inclusions, traces, oxides in a metal base and a decrease in the dynamic strength and stability of the structure and properties of cast iron, which leads to a decrease in impact-abrasive wear resistance and operational properties.

Nickel is a scarce and expensive component that reduces the stability of the structure and does not provide a significant increase in impact-abrasive wear resistance and performance properties; therefore, it is excluded from the composition of cast iron. The introduction of vanadium nitrides in an amount of 0.11-0.3 wt.% Dopes a metal mandrel, grinds carbides, increases the hardness and wear resistance of cast iron, which provides a significant increase in impact-abrasive and operational durability. Their content is based on a concentration of 0.11 wt.% in which there is an increase in hardness, impact-abrasive wear resistance and service resistance, and is limited to a concentration of 0.3 wt.% above which decreases the impact strength and crack resistance.

Yttrium in the amount of 0.07-0.13 wt.% Crushes and micro-alloyes the structure of cast iron in castings, increases the stability of the matrix and the elastic-plastic properties, which increases the operational durability. The microalloying and stabilizing effect of yttrium at a concentration of up to 0.07% wt.% Is not enough, and the performance properties of cast iron are low, and with an increase in the content of yttrium (more than 0 gs wt.%) impact abrasive wear resistance and performance properties of cast iron in cast products.

Chromium in the amount of 18.1-19.6 wt.% Provides the necessary hardening of the matrix, high characteristics of hardness and wear resistance, which leads to an increase in operational durability. With an increase in chromium content (more than 19.6 wt.%) Carbides grow larger, plastic and operational properties decrease, and with a decrease in chromium concentration (less than 18.1 wt.%), An insufficient amount of carbides in the structure decreases, a decrease in hardness, wear resistance and operational resistance to abrasive wear.

Sulfur and phosphorus contaminate the metal and reduce crack resistance, wear resistance and service resistance; therefore, they are excluded from the composition of cast iron.

Example. The smelting of cast iron is carried out in open induction furnaces with the main

lining and overheating of melts up to 1480-1520 ° С. The raw materials used are cast iron LK5, pig iron M1 and M2, steel and iron scrap, ferrochrome FH800. ferrovanadium FVdZN, ferromolybdenum FMO2. ferroboron and ferromanganese. Nitrided

ferrovanadium is introduced into the foundry ladle at

the release of the melt from the induction furnace.

The metal is poured into dry liquid-glass foundry molds at 1430-1450 ° C.

After normalization from a temperature of 850 ± 10 ° С, mechanical properties, impact-abrasive wear resistance, performance properties and microhardness of carbides on the PMT-3 device are determined. Impact strength is determined on samples of 10 x 10 x 10 mm of the type GOST 9454-78, and the relative wear resistance of the pU according to GOST

23.212-82.

In tab. 1 shows the chemical compositions of wear-resistant cast irons of the experimental heats; in tab. 2 - data on mechanical and operational properties and microhardness

carbides.

As follows from the table. 1 and 2, the addition of cobalt and boron, as well as nitrogen and vanadium in the form of vanadium nitrides to the composition of the proposed pig iron, allows to increase

shock-abrasive resistance 1.9-2.1 times.

Claims (1)

Claims of wear-resistant cast iron containing carbon, silicon, manganese, chromium, molybdenum, aluminum, yttrium and iron, characterized in that, in order to increase the impact-abrasion resistance, it additionally contains cobalt, boron, vanadium nitrides in the following ratio 5 components, wt.%: Carbon Silicon Manganese 0 Chrome Molybdenum Aluminum Yttrium Vanadium nitride 5 Cobalt Boron Iron 2.58-20.76 0.51-0.88 0.85-1.65 18.1-19.6 1.11-1.68 0.006-0.03 0.07-0.18 0.011-0.3 0.03-0.27 0.03-0.11 Else Table 1 Known cast iron contains 0.05 wt.% Nitrogen and 0.6 May. % vanadium. table 2