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Remelted steel by Rubiera
Acciaieria di Rubiera always pursues continuous improvement in the quality of steel products in order to meet the growing needs of its customers. In this context, Acciaieria di Rubiera has made numerous investments in recent years. It has expanded bottom casting facilities to produce ingots up to 130 tons, but the most important news is the acquisition of three remelting plants to improve the quality of steel (n°2 Electro-Slag remelting plants + n°1 Vacuum Arc remelting plant):
ESR 1800
to obtain ingots with diameter from 1000 mm to 1800 mm and weight from 30 t to 100 t.
ESR 1200
to obtain ingots with diameter from 700 mm to 1200 mm and weight from 12 t to 35 t
VAR 1090
to obtain ingots with diameter from 500 mm to 1070 mm and weight from 6 t to 27 t.
The slag for ESR plants can be produced in situ with a single-phase
electric furnace. |
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In the Electro Slag Remelting process an ingot is built up in a water cooled crucible by remelting a consumable electrode in a hot slag bath contained within the crucible.
The necessary heat for the melting of electrode is produced when current passes through the liquid slag by its electrical resistance.
By the choice of suitable melting conditions the shape of the liquid metal pool can be controlled such that homogeneous and segregation free ingots are obtained.
The liquid metal droplet formed at the tip of the electrode passes through the hot, metallurgically active liquid slag. Thereby excellent conditions for slagmetal reactions, such as the reduction of sulphur and oxygen, exist. |
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Vacuum Arc Remelting process consists of remelting an electrode by direct current electric arc under vacuum at a furnace pressure of less than 60 μbar. Refi ning takes place in the arc zone between electrode tip and molten metal pool on top of the ingot which solidifi es progressively in a water-cooled copper crucible.
The controlled solidification of the ingot results in an exceptionally sound and homogeneous material. In addition, strong degasification as well as a substantial improvement in nonmetallic cleanliness are accomplished by the furnace vacuum through dissociation of oxides at arc temperatures around 4000÷5000°C.
Achieve high cleanliness and minimize segregation means give the material superior hot and cold workability and better transverse mechanical properties. Therefore, this choice was made to further increase the level of quality achievable in an ingot obtained by the traditional process.
BENEFITS
Why our customers have already chosen Rifuso di Rubiera?
- Because is used to 100%.
With Rifuso di Rubiera it isn’t necessary cut hot top and bottom of the ingot, whereas in a traditional ingot must be cut until 30% of the starting material. 35 t of Rifuso di Rubiera are equivalent to 52 t of traditional ingot and all at an incomparable quality.
- Because reduces transport costs until 40%.
Carry 35 t of Rifuso di Rubiera is cheaper than carry 52 t of traditional steel.
- Because drastically reduces the non-compliance.
The remelting process gives an excellent quality through all thickness of the ingot reducing the inclusions content and segregation.
- Because reduces processing and forging costs.
Rifuso di Rubiera is more compact, dense and light and thus requires less time and energy during forging: the reduction ratio can drop to 2:1.
- Because expands the products range of our customer.
Starting from 35 t of Rifuso di Rubiera, a forge, with no upgrade of equipment (manipulators, pre-heating furnaces, etc. ..), can obtain a fi nal product of such size as to require a traditional starting ingot of 52 t.
- Because allows the customer to access to new markets.
Today the most advanced technological applications require with increasingly frequency electroslag (ESR) or vacuum arc (VAR) remelted products.
EXAMPLE OF ECONOMIC CHEAPNESS
| TRADITIONAL INGOT |
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RIFUSO DI RUBIERA |
| 52 t |
Ingot weight |
35 t |
| 2.000 €/t |
Ingot cost |
3.140 €/t |
| 29 €/t |
National Transport |
24 €/t |
| 2.029 €/t |
Total Cost (€/t) |
3.164 €/t |
| 105.508 € |
INGOT TOTAL COST (€) |
110.740 € |
| Traditional Forging Cost |
PROCESSING AND FORGING COST |
Cost Saving |
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Buying Rifuso di Rubiera will allow forging cost saving, that will offset largely the minimum price difference (+5%)
compared to conventional ingot.
You will also have a product:
- of superior quality
- that will expand your products range
- opening new and more profi table markets
EXAMPLE OF QUALITY IMPROVEMENT
| Traditional process |
VAR |
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Figure 1. Comparison of cleanliness and microsegregation in air melted and Vacuum Arc remelted stainless steel (mag.100x)
Download the brochure in .pdf format (1,87 Mb)
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