DESC:FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2016

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
TITLE
“PRODUCTION OF SUPERNI 276 IN VIM FURNACE & RECOVERY OF MAGNESIUM IN ESR USING SPECIAL SLAG”
APPLICANT
(a) Name : Mishra Dhatu Nigam Limited
(b) Nationality : Indian
(c) Address : PO Kanchanbagh, Hyderabad, Telangana – 500058, India

The following specification particularly describes the application and the manner in which it is to be performed.
PRIORITY STATEMENT
The present application hereby claims priority from Indian patent application with the application number 202341031469, filed on 3 May 2023, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD OF INVENTION
The present invention relates to metallurgical processes and alloy development. More particularly, it relates to production of Superni 276, a nickel-based superalloy using vacuum induction melting (VIM) and electroslag remelting (ESR) processes.

BACKGROUND OF INVENTION
Superni 276 is a nickel-based superalloy that is known for its excellent resistance to corrosion and oxidation at high temperatures. It is composed of nickel, chromium, molybdenum, and tungsten, which give it high strength, good weldability, and resistance to a wide range of corrosive environments.
Magnesium retention is an essential aspect of forging superalloys. It is often used as an alloying element in superalloys because it helps to improve their high-temperature properties, such as creep resistance and strength retention. However, magnesium can be difficult to retain during the forging process, which can lead to a reduction in the alloy's high-temperature properties.
In this context, magnesium retention is crucial in forging superalloys because it helps to maintain their high-temperature properties, which are essential for their performance in critical applications.
With this background, the present invention discloses a novel method of production which addresses the challenge of retaining Magnesium, during the production of Superni 276 to enhance its high-temperature properties.

OBJECT OF THE INVENTION
The primary object of the invention is to provide a method for producing a nickel-based superalloy, Superni 276, with enhanced magnesium using Special Slag.
Another object of the invention is to develop of process that effectively incorporates magnesium into the alloy composition without significant evaporation loss during melting.

SUMMARY OF THE INVENTION
This summary is provided to introduce a selection of concepts, in a simplified format, that are further described in the detailed description of the disclosure. This summary is neither intended to identify key or essential inventive concepts of the disclosure nor is it intended for determining the scope of the disclosure.

A method for retaining Magnesium during production of superalloy, SUPERNI 276 to enhance forgeability and high-temperature properties of the alloy, the method comprising the steps of melting a composition comprising nickel, chromium, molybdenum, tungsten, cobalt, iron, manganese in a Vacuum Induction Melting (VIM) furnace at 1550 degree C for 2-3 Hrs under 10-3 mbar argon pressure; Refining the said melt to reduce the level of carbon to 0.008%, Employing a 40 Kg nickel container filled with 20-25 kg of magnesium in a batch to retain and prevent evaporation of magnesium during melting; and performing secondary melting to produce ingot in Electroslag Remelting (ESR) using special slag under argon pressure to further protect the loss of Magnesium.

DESCRIPTION OF THE INVENTION

The present invention discloses a novel method for retaining the Magnesium while production of Superni 276 in VIM Furnace and ensuring recovery of Magnesium.
Superni 276 is a high-performance superalloy that is commonly used in a variety of high-temperature applications. The weight percentage composition ratio of this alloy is as follows:
• Chromium (Cr): 15.5%
• Molybdenum (Mo): 15.5%
• Tungsten (W): 3.5%
• Cobalt (Co): 1.7%
• Iron (Fe): 5-7%
• Manganese (Mn): 0.17%
• Nickel (Ni): Balance
The Composition does not include Magnesium, but it is one of the important elements required for forgeability of super alloys. However, pure magnesium cannot be directly incorporated during primary melting, as it will evaporate during the melting process.
Herein, the primary melting to produce super alloy is performed using vacuum induction melting (VIM) and scrap is added and refined during this process.
In accordance with an embodiment of the present invention, during the primary melting, which is performed using VIM, the scrap is melted at a temperature of 1500-1600°C for 2-3 hours under 30-100 bar argon pressure in vacuum. The resulting melt is then refined to remove gases namely carbon or any other gases that may have been introduced during the melting process. The refining is done at 10-3 mbar at temp of 1550 degree C. The first stage of refinement is degassing; the vacuum environment present in VIM facilitates degassing. As the scrap metal gets heated and melted under vacuum, the solubility of gases decreases, causing it to come out of solution and form bubbles that rise to the surface of the melt. The pumping system continuously evacuates the gases from the chamber, effectively degassing the molten metal. During refinement, it is essential to have precise control of the melting temperature. The temperature herein is maintained at 1550 degree C. This refinement process reduces the level of carbon to 0.008%, which helps to improve the alloy's strength and ductility.
Post refining chemistry is adjusted. Herein the term ‘chemistry is adjusted’ refers to the steps taken towards analyzing and controlling the chemical composition of the molten metal to achieve specific desired properties and characteristics in the final product i.e. SUPERNI - 276.
In accordance with an embodiment of the present invention, the alloying elements such as chromium (Cr), molybdenum (Mo), tungsten (W), cobalt (Co), manganese (Mn), and others are added to the molten metal to impart desired properties. The addition of Magnesium at this stage will result in its evaporation as Magnesium has a low melting point.
Hence, once the chemistry is adjusted, the process of addition of Magnesium takes place.
In accordance with an embodiment of the present invention, it is very important to ensure the presence of Magnesium i.e. retaining the Magnesium in the VIM as it evaporates very easily.
Accordingly, a novel and inventive method is designed to ensure Magnesium does not get evaporated. Herein, a container or box is prepared which is made of Nickel. And inside this Nickel container, the Magnesium is kept.
In accordance with an embodiment of the present invention, based on the calculations since the weight of the batch is 8000 kg or 8 Ton; a Nickel container of 40 Kg is prepared, and 20-25 Kg of Mg is added in each batch.
In accordance with an embodiment of the present invention, Magnesium has a low melting point, 80% of it evaporates easily. The Magnesium is retained in the molten metal. Further, the chemical composition of the molten metal is analysed using analytical techniques namely spectroscopy and chemical analysis to ensure the presence of Magnesium.
Further, Secondary melting is performed for production of Ingot in ESR. The secondary melting also results in loss of Magnesium. To retain the Magnesium or to protect the loss of Magnesium during the secondary melting, a special slag is prepared and used. Special slag is specifically designed for the protection and retention of Magnesium loss during the secondary melting.
Further, in the present invention, the secondary melting is performed in Argon pressure to ensure that the magnesium is not lost and further avoid any explosion which may occur if Magnesium comes in contact with the atmospheric oxygen.
In the present invention, Argon pressure and special slag is used to retain Magnesium during the secondary melting. The special slag comprises of 70% fluorspar, 5% MgO, 10% CaO and 15% Al2O3. Herein MgO is added intentionally to ensure retention of Magnesium.
This specialized slag composition enables maintaining of the desired alloy composition and properties of the final Superni 276 product by effectively managing the presence of magnesium for the forging process.
In accordance with an embodiment of the present invention, special slag is used to protect the loss of Mg during secondary melting. Herein melting is done in Argon pressure.
Novel and Inventive Aspects of the Invention
• Magnesium Retention Technique: The use of a nickel container filled with Magnesium to retain magnesium during the VIM process is a unique and inventive approach. This technique prevents the evaporation of magnesium, which has a low melting point, during the high temperature melting and refining stages.
• Incorporation of Magnesium in SUPERNI 276 Production for Improved Forging: The present invention discloses incorporation of magnesium, an important alloying element for improving forgeability and high-temperature properties, into the SUPERNI 276 alloy during the primary melting process.
• Preventing Loss of Magnesium during Secondary Melting in ESR with Special Slag and under Argon Pressure: While performing the secondary melting in ESR, the employment of novel special slag of specific composition and Argon pressure to prevent the loss of magnesium is another inventive step.
• Controlled Vacuum Induction Melting (VIM) Process: The disclosed process parameters are critical of achieving the desired result i.e. retention of Magnesium in SUPERNI 276 for forging.
The above-mentioned inventive steps overcome the challenges of retaining Magnesium for the production of SUPERNI 276 superalloys with enhanced forgeability and high-temperature properties.

ADVANTAGES AND APPLICATION
Superni 276 is Super Alloy which is commonly used in applications that require high performance in harsh environments, such as chemical processing, marine engineering, and oil and gas production. It is particularly well-suited for use in environments containing sulfuric acid, hydrochloric acid, and seawater.
,CLAIMS:Claims:
We Claim

1. A method for retaining Magnesium during production of superalloy, SUPERNI 276 to enhance forgeability and high-temperature properties of the alloy, the method comprising the steps of:
a. Melting a composition comprising nickel, chromium, molybdenum, tungsten, cobalt, iron, manganese in a Vacuum Induction Melting (VIM) furnace at 1550 degree C for 2-3 Hrs under 10-3 mbar argon pressure;
b. Refining the said melt to reduce the level of carbon to 0.008%,
c. Employing a 40 Kg nickel container filled with 20-25 kg of magnesium in a batch to retain and prevent evaporation of magnesium during melting; and
d. Performing secondary melting to produce ingot in Electroslag Remelting (ESR) using special slag under argon pressure to further protect the loss of Magnesium.

2. A method as claimed in claim 1, wherein the magnesium is introduced into the molten metal using a nickel container filled with Magnesium wherein the nickel container is submerged in the molten alloy during the vacuum induction melting (VIM) process

3. A method as claimed in claim 1, wherein per batch is approximately of 8000 kg.

2. A method as claimed in claim 1, wherein the secondary melting with special slag is conducted under argon pressure.

3. A method as claimed in claim 1, wherein the special slag comprises of 70% fluorspar, 5% MgO, 10% CaO and 15% Al2O3.

4. A method as claimed in claim 1, the composition of resulting superalloy, SUPERNI 276 in wt% is Chromium (Cr): 15.5%, Molybdenum (Mo): 15.5%, Tungsten (W): 3.5%, Cobalt (Co): 1.7%, Iron (Fe): 5-7%, Manganese (Mn): 0.17%, Magnesium (Mg): 0.2-0.3% and balance Nickel (Ni).

5. A method as claimed in claim 1, wherein the vacuum induction melting (VIM) process is controlled to achieve SUPERNI 276 with optimized magnesium content, wherein the magnesium contributes to its improved forgeability and thermal stability.