Technical Pages- Cored Wire Method

The cored wire injection Process

Cored wire injection has become increasingly popular since the 1980s due to its low cost and versatility.

SB Misra, Minex Metallurgical Company Limited

High productivity, precise quality oriented production processes such as secondary metallurgy are being increasingly used in steel melt shops. Steel treatment and composition adjustment methods used with secondary metallurgy process demand speed, high recovery, consistence, cleanliness, accuracy and flexibility.

Cored wire injection is an automated method of introducing metallurgical powder in molten steel which meets the above criteria at low investment.

One of the main problems, of secondary metallurgy is introducing metals and alloys with high reproducibility and recovery into the melt. These elements are more conveniently introduced by the wire injection process. Cored wire injection metallurgy introduces the metallurgical powder deep inside the melt at a critical depth through a sacrifical steel tube.

Cored Wire Manufacture

The cored wire is manufactured by encapsulating graded powder in steel sheaths and packaging the wire in variable sized coils. These coils are produced in sizes ranging from 100-3000 kgs. Wire diameters range from 5-18 mm. Injection of the wire is carried out in full ladle either in a ladle furnace, a ladle station or a tundish, using a specially designed wire feeder.

These feeders are designed for sequence or simultaneous injection and available in one to four standard configurations to feed a wide range of wire sizes in predetermined speeds and lengths. Many stations have been installed to operate with remote and computerised control. The simplicity of the design is a factor in the low capital investment.

Cored Wire Injection Applications

The principal impetus for cored wire injection was the increased use of calcium and its alloys in continuous casting, although it is now applied elsewhere. It is applied in the following metallurgical applications :

Calcium treatment : This is generally used for oxides and sulphides shape control, resulting in liquid lime aluminate and underformed sulphides. It guarantees cleanliness, castability and machinability.

Aluminium injection : This is used for deoxidisation and alloying in the steel industry. In bulk aluminium addition, optimisation of wire diameter and feeding rate are of vital importance from both the production and recovery point of view.

Its main advantages are reduced aluminium consumption, steel cleanliness, and improved control.

Desulphurisation of hot metal :Magnesium cored wire is economically suitable for desulphurisation of blast furnace hot metals. It involves low capital investment and high desulphurising efficiency.

Micro allying : Ferro titanium, ferro beron, ferro niobium, ferro vanadium, tellerium and selenium are all used for micro alloying.

Trimming addition : The progressively more stringent analysis requirement for carbon makes cored wire injection an attractive solution. The efficiency is close to 100 percent and extremely high accuracy is feasible.

The traditional resulphuring of steel produces machinability, but decreases mechanical property, due to improper modification of oxide and sulphide inclusion in rolled and forged material.

Tundish injection : The tundish metallurgy for control of temperature, trimming addition of calcium and other micro alloys is becoming an important tool for steel making and wire injection is increasingly used for this.

Foundry application : In recent years, the cored wire injection process has been accepted as the preferred process by many foundries for SG iron treatment. The foundry industry uses the wire injection process for desulphurisation, inoculation spherodising and alloying.

Non ferrous industries : Although the greater bulk of cored wire consumption is used in the steel industry in which steel sheath is desirable, there is also potential demand for copper and aluminium based wires.

Wire injection is a practical, cost effective way for increasing productivity and steel quality. It can be applied to aluminium bulk and trim alloying, calcium treatment, micro alloying, trim additions, and tundish metallurgy.

Biography
SB Misra is the managing director of Minex Metallurgical Company Limited, produces of speciality ferro alloys.