Secondary steel making processes are used to further refine special steels produced through primary steel making. These secondary processes are critical for achieving stringent quality requirements for cleanliness, grain size, and hardenability in steels used for applications like aircraft components and pipelines. Various furnaces and techniques can be used for secondary refining, including ladle furnaces, argon oxygen decarburization, vacuum treatments, and stirring to homogenize temperature and composition and accelerate inclusion removal from the steel. Stirring is commonly done by bubbling gas through the steel bath via submerged lances or porous plugs, or using electromagnetic stirring.

1. MY: 301 Steel Making Processes
Secondary Steel Making /Special Steel Making / Clean Steel:
• For most application, the surface quality, internal quality, micro-
cleanliness quality and mechanical property of the steel produced
by primary steel making (open hearth, LD, EAF, BOS etc) are
satisfactory and hence these processes meet the specification and
the customer’s requirements.
• However the quality requirements of special steels in terms of
cleanliness, grain size, hardenability range etc have become quite
stringent in recent year.
• E.g. rotor, special forgings, aircraft and space-craft components,
plates for ships and submarines, pipeline, electrical steel and so
on.
• The secondary steel making is the critical step in the
steel production between the primary and the casting.
• Some elements are added and some have to be remove during
secondary steel making, Several type of furnaces and equipments
are used for this purpose.
• Each has a specific role to play and their use is selected depending
upon the particular requirement of the type of steel being made.
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2. MY: 301 Steel Making Processes
Secondary Steel Making Operation/Process Varieties:
It involves the following options.
1) Stirring treatments
i. Lance
ii. Bottom Pouring Plug
iii. Electromagnetic Stirring(EMS)
2) Synthetic Slag Refining with stirring.
3) Ladle Furnace
4) Decarburisation Techniques
i. Argon-Oxygen-Decarburisation (AOD Process)
ii. Vacuum-Oxygen-Decarburisation (VOD Process)
5) Injection Metallurgy (Ladle Injection)
i. Powder
ii. Wire
6) Post-Solidification Treatment
i. Vaccum Arc Remelting (VAR)
ii. Electro Slag Remelting (ESR)
7) Vacuum Treatment / Degassing
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3. MY: 301 Steel Making Processes
1) Ladle Furnace(LF)
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4. MY: 301 Steel Making Processes
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5. MY: 301 Steel Making Processes
2)Stirring treatments/techniques
Ladle Stirring is an essential operation during secondary steel
making in order to achieve.
i. Homogenize bath temperature.
ii. Homogenize bath composition.
iii. Facilitate slag-metal interaction essential for the
processes such as desulfurization
iv. Accelerate the removal of inclusion in the steel
v. Cleanliness improvement
In practice stirring is achieved by
i. Argon/Nitrogen gas bubbling in the refined steel bath
either via a submerged lance or by porous plugs in the
bottom of the ladle.
ii. Electromagnetic Stirring (EMS)
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6. MY: 301 Steel Making Processes
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7. MY: 301 Steel Making Processes
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8. MY: 301 Steel Making Processes
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