RU1772171C - Method for deoxidation and microalloying of low-alloyed low-carbon steel - Google Patents

Abstract

The invention can be used in metallurgy in the production of low-alloy mild steel. Essence: the minimum amount of niobium required for microalloying is determined depending on the total content of carbon, sulfur and phosphorus in the melt according to the formula: (% Nb) 0.04 + I (% C), (% S), (% P) 8K. where (% Nb) is the minimum amount of niobium required for microalloying, wt.%: 1 {% C), {% 5). (% P) is the total content of carbon, sulfur and phosphorus in the melt before deoxidation,%; K is an experimental coefficient taking into account the assimilation of niobium, equal to 0.85-0.95.

Description

The invention relates to ferrous metallurgy, in particular to a technology for the production of microalloyed steels.

A method is known for the deoxidation of structural low alloy steel microalloyed with titanium, in which process parameters are proposed to stabilize the absorption of titanium.

The disadvantage of this method is that it does not provide an increase in the cold resistance of steel

A method is known for deoxidizing mild steels, leading to a significant increase in the ductility of steel. The required ductility is achieved by microalloying with aluminum, consumption

which is determined by calculation, depending on the content of silicon and carbon in the steel. The disadvantage of this method is that it does not improve other properties of the steel, including cold resistance.

The closest in technical essence and the achieved result to the claimed method is the technology of microalloying niobium of low-carbon welded steel in order to increase the complex of mechanical properties. The technology provides for screening and determination of sulfur, phosphorus and carbon in the metal before deoxidation and addition to the melt, narc do with silicon. manganese and aluminum niobiumso Serge Ch 1

Yu

l

Xj

alloying materials after the introduction of aluminum. The consumption of niobium is determined by the grade of steel.

The disadvantage of this technology is that it does not take into account the combined effect of impurities present in the metal (sulfur, phosphorus, carbon) and niobium on the toughness of steel, including at low temperatures, and also does not realize the possibility of reducing the consumption of niobium with the right combination of these elements.

The aim of the invention is to increase the toughness of steel while reducing the consumption of niobium used for microalloying.

This goal is achieved in that in the known method for the oxidation and microalloying of low-alloy mild steel, including sampling and chemical analysis of the sample before oxidation, introducing silicon, manganese, aluminum and niobium into the metal, alloying is carried out with the minimum amount required for microalloying niobium, determined by the formula

go / Nhl 0 ..% 3.% RE

1/0 J8 K

where% Nb is the minimum amount of niobium required for microalloying, wt.%;

,% S, total content of carbon, sulfur and phosphorus in the melt before melting, wt.%;

K is an experimental coefficient that takes into account the absorption of niobium, equal to 0.85-0.95.

The essence of the claimed method of deoxidation and microalloying of low alloyed low-carbon steel is that a minimum amount of niobium sufficient for microalloying is placed in the bucket, the mass of which guaranteeing an increase in the toughness of steel is determined by calculation, depending on the total carbon, sulfur and phosphorus in a metal sample taken before deoxidation.

The relationship between the required amount of niobium introduced into the metal and the content of carbon, sulfur and phosphorus in the melt before oxidation has been experimentally established. The solution is applicable for steels with a carbon content of 0.06-0.18%, i.e. for mild weldable steels.

The table shows the test results of the metal of experimental melts and melts according to the prototype method. The melts were carried out in open-hearth furnaces with a capacity of 400 tons. After sampling and analysis of the metal sample before deoxidation, silicomanganese was introduced into the furnace based on the production of 1.5% Mn in finished steel and after 10 minutes the metal was discharged into the ladle. At the time of release, ferrosilicon was added to the ladle in the calculation of 0.25-0.27% silicon in the finished steel.

aluminum in the amount of 1 kg / t of steel and ferroniobium. The amount of niobium administered was determined by the proposed formula, i.e. depending on the content of carbon, sulfur and phosphorus in the melt before deoxidation. The metal of all the heats was rolled onto a 10 mm thick sheet. Impact strength tests (table) were carried out in accordance with GOST 9454-78 on samples cut across the rolling direction.

These tables confirm the possibility of increasing the toughness of steel with a minimum consumption of niobium for microalloying, taking into account the influence of carbon, sulfur and phosphorus present

in the melt.

Claims (1)

SUMMARY OF THE INVENTION A method for the deoxidation and microalloying of low-alloy mild steel, including sampling and chemical analysis of a sample before deoxidation, introducing silicon, manganese, aluminum and niobium into the metal, characterized in that, in order to increase the toughness of the steel while reducing the consumption of niobium, alloying the wire t the minimum amount required for microalloying niobium, determined by the formula% Nb 0 ..% S.% P where% Nb is the minimum amount of niobium required for microalloying, wt.%; . % S,% P - total content of carbon, sulfur and phosphorus in the melt before deoxidation, wt.%; K is an experimental coefficient that takes into account the absorption of niobium, equal to 0.85-0.95.