SU1098971A1 - Cast iron - Google Patents

Abstract

CAST IRON containing carbon, silicon, manganese, chromium, nickel. molybdenum and iron, about t and ch and y with the fact that, in order to increase resistance to warping and cracking in the temperature range 273-673 K, it additionally contains vanadium in the following ratio of components, wt.%: Carbon3.0-3.5 Silicon1.6-2.2 Manganese0.7-1.0 Chrome0.55-0.8 Nickel0.3-1.0 Molybdenum 0.06-0.15 Vanadium0.02-0.1 IronErest

Description

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with

The invention relates to ferrous metallurgy, in particular, to cast iron compositions with enhanced heat resistance at temperatures of 273-673 K, which are used to make cast iron casting molds, for example, chill molds for casting aluminum or bronze casting.

Known cast iron for the manufacture of chill molds with a complex configuration l composition, wt.%:

Carbon -3.1-3.4 Silicon1.4-1.7

Manganese 0.8-1.2

Nickel0.25-0.35

Chrome, 1-0,2.

IronErest

However, such cast iron has insufficient wear resistance and is prone to thermal cracking, which negatively affects the durability (performance) of the chill mold.

The closest to the invention to the technical essence and achievable properties is cast iron 2J composition, wt.%:

Carbon3,2-3,8

Silicon1.8-2.6

Manganese 0.1-0.5

CHROM0,1-0,6

Nickel 0.5-3.5

Molybdenum 0.1-0.6

IronErest

The known cast iron has a low hardness (HB 200-220), a relatively high heat resistance, intended for the manufacture of thin-walled (up to 25 mm) chill molds, has a low ductility and resistance to warping and cracks. The aim of the invention is to increase resistance against warping and cracking in the temperature range 273-673 K.

This goal is achieved by the fact that cast iron containing carbon, silicon, manganese, chromium, nickel, molybdenum and iron additionally contains vanadium with the following ratio of components, wt.%:

CarbonV 3.0-3.5

Silicon1,6-2,2

. Manganese 0.7-1, 0

Chrome 0.55-0; 8

Nickel0.3-1.0

Molybdenum 0.06-0.15

Vanadium 0.02-0.1

IronErest

As an impurity, cast iron can contain up to 0.12% sulfur and up to 0.2% phosphorus.

Doping of cast iron with vanadium with molybdenum contributes to obtaining a fine-grained structure throughout the cross-section of a chill mold with a wall thickness of 15-60 mm. Vanadium interferes with grain growth, reduces solid fall

During tempering, it allows the use of high tempering temperatures, contributing to the production of cast iron with higher ductility. The fine-grained and homogeneous structure of cast iron, 5 containing vanadium, causes high mechanical properties. Cast iron with vanadium well overheats, which allows for heat treatment

0 at wider temperature ranges.

The effectiveness of the alloying of gray iron to reduce the tendency of castings to form

5 cracks and warping markedly increased (by 40-60%) during annealing (heating to a temperature of 8731013 K, exposure 1.5-4.0 hours with slow cooling in the furnace). Annealing

0 relieves foundry stresses and stabilizes the size of iron castings (chill molds). The purpose of annealing is the formation of dispersed phases. Annealing regulates the amount of carbide phase in cast iron

5 and the degree of alloying of the solid solution, which increases the ductility of cast iron. To improve the ductility of cast iron, it can be established that it is prone to cracking and warping.

 The combination of vanadium with molybdenum, chromium and nickel gives gray, cast iron after heat treatment (annealing) the most high resistance to cracking and warping under sudden temperature fluctuations than with other known combinations of alloying additives.

Nickel has little effect on the size of the iron grains, but increases the hardness

0 and strength, increases hardenability and increases strength at high temperatures. Since the chill tooling operates at temperatures not higher than 673 K, the nickel content in

5 cast iron is sufficient in the range of 0.3-0.1% to ensure high strength and hardness of the dies during operation.

The microstructure, which is formed from the vacuum of the gun castings after annealing, most fully satisfies the requirements that are imposed on the structures of the alloys, operating in the modes of heating, oxidation.

In order to obtain cast iron of the proposed composition, the metal is smelted in an ICTT-1M induction crucible furnace with acid lining. The alloying elements — chromium, bromide, nickel, and vanadium — are introduced as doped carbon in a liquid bath. Manganese - in the form of ferromanganese. Crushed ferrosilicon is introduced in 2-3 minutes before casting, the superheating temperature of cast iron is 17331763 K, the pouring temperature of the mold is 5 1613-1633 K.

In tab. 1 shows the proposed chemical compositions of cast iron, in table 2

their mechanical and service properties in the cast and heat-treated state.

Table 1

Table

Claims (1)

CAST IRON containing carbon, silicon, manganese, chromium, nickel, About f V “3 / and 1, 6-2,2 0.7-1.0 0.55-0.8 0.3-1.0 0.06-0.15 0.02-0.1 The rest is molybdenum and iron, with a l of a rata and th with the fact that, in order to increase the resistance to warping and the formation of cracks in the temperature range 273-673 K, it additionally contains vanadium in the following ratio of components, wt.%: Carbon Silicon Manganese Chrome Nickel Molybdenum Vanadium Iron for manufacturing configuration '3.1-3.4 1.4-1.7 0.8-1.2 0.25-0.35 0.1-0.2. Rest 3.2-3.8 1.8-2.6 0.1-0.5 0.1-0.6 0.5-3.5 0.1-0.6 The rest (HB = 200-220), heat resistance, manufacturing tons) chill molds, plasticity and