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    Development of Heavy Steel Forgings for Nuclear Energy


    G K Pillai,

    Chairman cum Managing Director

    Heavy Engineering Corporation Ltd.



    In view of the governments decision, to set up a number of nuclear power plants, in collaboration with western

    countries, Indian companies needed to upgrade the existing level of technological processes to meet the demand for

    high quality steel forgings. Till date, only a few countries in the world have the technical knowhow and the facilities

    for making the forgings. Due to the stringent quality requirements of the nuclear grade steels, a very high order of

    technological processes for making clean steel, forging, heat treatment, machining and testing is required.To develop the capability within our country, Heavy Engineering Corporation Ltd, Ranchi, a Public Sector Unit,

    under the Ministry of Heavy Industries & Public Enterprises, took the lead in developing the processes required to

    manufacture a 25MT Shell forging, from a 120MT ingot. This paper deals with the various innovative technological

    practices developed and established in the Foundry Forge Plant (FFP) of HEC Ltd


    The steel forgings in a nuclear reactor are continuously exposed to nuclear radiation, high temperature and pressure.

    To withstand these effects, steel grades with high toughness requirements and very low levels of impurities are

    required to make the forgings. Also, the forging processes involve upsetting of heavy Ingots, punching, mandrel

    forging, ring rolling and drawing. To ensure the required steel quality, it is essential to control the levels of

    impurities like Phosphorous, Sulphur, Hydrogen, Arsenic, Copper, and Cobalt etc, much below the levels presently

    achieved. Only a few countries like, Japan, S Korea, Italy, France have the facilities to supply such forgings. In

    India, some forge shops are making smaller items such as Nozzles but these are made from imported ingots/blanks.

    HEC Ltd, Ranchi, though primarily set up to meet the demand of Steel and Mining sectors, has decided to enter the

    high tech sector of making forgings for nuclear power equipments. It has unique facilities for steel making, forging,

    heat treatment, machining and testing in one location. Though the requirements are very stringent and the

    equipments were required to be utilized at their optimum levels, HECL has ventured to develop the processes for

    making heavy ingots upto 120 MT and forgings weighing about 25 MT,

    Product range of Foundry Forge Plant (FFP) and production facilities

    FFP supplies castings and forgings for various equipments for Steel, Mining and General Engineering sectors,

    besides Main BG Crankshafts for 16 cylinder engines for Railways and some special items for shipyards, space and

    defence sectors. The heaviest of the forgings, such as Main Shaft for Crusher, weighed about 50MT, forged from a

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    87T ingot. The quality requirements include tests for chemistry, mechanical tests at room temperature and ultrasonic


    The main production equipment are:

    Primary steel making units: Electric Arc Furnaces 30T Capacity- 2 nos.,10T Capacity- 1 no.

    Secondary Steel making units: Vacuum Arc Degassing Furnace 60T Capacity- 1 no., Ladle Furnace- 1 no. and

    Stream degassing Unit 90T Capacity- 1 no

    Hydraulic Presses: 6000T Capacity- 1 no., 2650T Capacity- 1 no., 1650T Capacity- 1 no. and 1000T Capacity- 1


    Development of Shell Forging weighing about 25T for BARC by HEC

    1) Description of ForgingSupply size: 3000mm length (approx.) and 400 mm thick

    Material grade: Low-Carbon, Chrome-Moly-Vanadium steel, with very low levels of impurities

    Heat Treatment: Quench and temper

    Mechanical tests, along Axial, Tangential and Normal directions for Tensile tests at Room Temperature and at

    3500C, establishing Ductile Brittle Transition Temperature(Tko), determination of Nil Ductility Transition

    Temperature(Pellini Drop Weight Test)

    Non Destructive Examination (Ultrasonic and Magnetic Particle tests)

    2) Challenges in manufacturing of the Shell ForgingFor making the shell forging, a black forging of size about 3500mm ht. was required to be forged from a 120T

    ingot. The following technological constraints were identified in manufacturing of the forging.

    a) Capacity constraints in making 120T of steel melt and chemistry with very low levels of impurities, gases

    and inclusions.

    b) Capacity constraints in upsetting of 90T forged block in the 6000T press.

    c) Effective Quality Heat Treatment ( Water quench and Tempering) to ensure uniform properties in all three

    directions and across the thickness

    d) Machining of the shell forging, to meet the requirements for perpendicularity within 0.1mm and

    concentricity of all diameters within 0.05mm with respect to the inside diameter

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    3) Technological solutions and the risks encountereda) Impurities in the raw materials, deleterious to low temperature impact properties during service were

    controlled through

    revision of quality standards for steel scrap

    revision of quality standards for fluxes, ferro alloys and argon

    Special scrap, with very low levels of impurities, was procured from Bokaro Steel plant and alloying

    additions such as metallic Chromium, metallic Manganese with low levels of Arsenic and Phosphorous were

    used for making the steel.

    b) Fig. 1 schematically shows the route followed for realizing 120T of fully refined metal for pouring the

    ingot. Through meticulous planning, monitoring and coordination, our Engineers succeeded in

    synchronizing the bath chemistry of 5 melts, latter matching the chemistry of refined metal in

    Vacuum Arc Degassing Furnace (VAD) and Ladle Furnace (LF).

    managing the logistics of hot metal handling and the risky operation of hot metal holding of the 1st

    batch of refined metal in LF for 12 hours.

    control of exogenous inclusions while handling of the metal from 6 refractory lined ladles and

    achieving the cleanliness even after such long holding

    c) In order to control the hydrogen in the steel to a level of less than 1ppm, a Package Boiler exclusively for

    the vacuum degassing unit was installed to achieve very low vacuum levels . Further, controls at every

    stage of processing were implemented, to reduce hydrogen input in to the metal.

    d) Fig 2 schematically shows the route followed for forging and further processing. Through section hot

    working, in the 6000T press was a key operation in achieving isotropic properties of the product. The

    capacity constraint on this account was resolved by

    design, manufacture and use of a Rotating Table for partial upsetting of the heavy forged block,

    through successive rotations

    e) FFP has gas fired furnaces for heat treating such big forgings. However, to ensure uniform metallurgical

    and mechanical properties and satisfy the ultrasonic requirements, we have

    developed a heat treatment technology

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    carried out the heat treatment in a specially installed Electric Pit Furnace.( 3500mm dia X 8000mm


    f) To achieve the strict dimensional tolerances, the forging was machined, using

    CNC Vertical Turning and Boring Machine, for finish machining

    CNC Horizontal Boring Machine, for locating the nozzle location and slicing of Test piece rings

    from the job.

    4) Production of Shell forgingThe various stages of manufacturing, starting from Preliminary refining in 30T EAF, till final despatch of the

    forging are shown in the following process charts and photographs.


    Fig. 1

    Steel Making in 2 Batches

    Very High Purity


    Alloying Additions

    High Purity Metallic


    Transfer of Metal to


    120 Ton


    Pouring under


    Secondary Refining

    and degassing in 60T


    Secondary Refiningand degassing in 60T


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    Primary Refining of Steel in 30T EAF Secondary Refinement in 60T VAD

    Stripping of 120T Ingot from mould

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    Fig. 2

    Ingot for Forging

    Forging operation in

    6000T Press

    Preliminary H/T

    Rough Machining

    Quality H/T

    (Quench & Temper)



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    Holding of 120T Ingot for Pin Forming Forging of Ingot into block

    Block Forging for Upsetting Upsetting of Block

    Upsetting of Block on rotating table

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    Punching Operation

    Ring Rolling on Mandrel Drawing on water cooled taper mandrel

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    Step Forging Finished Shell Forging

    Set up for Ultrasonic testing Despatch of Finish Machined Forging

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    5) Quality of the Forgings Developed for nuclear sectora) Control of Impurities

    Table 1- Impurities

    Fig.3 Level of impurities in a number of melts

    b) Distribution of different elements in a number of melts


    Copper < 0.05%

    Phosphorus < 0.006%

    Sulphur < 0.004%

    Hydrogen < 1.5 ppm

    Other impurity

    elements< 100 ppm












    Ni Mn Si Cu








    P S Sn Al As Sb

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    Homogeneity of Properties

    Fig.5 - Yield Strength (MPa) at Room Temperature

    Fig.6 - Impact Energy at 15 deg. C









    0 0.25 0.5 0.75 1

    Fraction of Section Thickness








    0 0.25 0.5 0.75 1

    Fraction of Section Thickness




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    d) Low temperature properties

    Fig.7 - Low temperature Impact Energy

    Other products of HECL for Strategic Sectors

    HEC has made significant contributions to the defence and space sectors also, besides its core strength areas of steel

    and mining sectors. Some equipment and components HEC has manufactured for the Defence and Space Sectors


    Space and Atomic Energy Sectors

    High tech heavy duty structural

    Mobile Launch Pedestal

    Folding cum Vertically Repositionable Platform (FCVRP)

    Horizontal Sliding Door

    Heavy Duty Overhead Cranes

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    Special Purpose CNC machine tools

    Development of Special grade steel (15CDV6)

    10 Ton Hammer Head Tower Crane installed at the top of Umbilical Tower of 80 M Height

    400 TON crane at ISRO / SHAR (Installed at 46 M Ht in Solid Stage Assembly Building of GSLV

    Mk-III Project at SHAR to facilitate Assembly of Launch Vehicle.)

    6 AXIS, CNC Vertical Turning & Boring machine for ISRO

    Design and manufacture of Magnet Pole Caps and other components of Super Conducting Cyclotron

    Magnet (K-500) for Variable Energy Cyclotron Centre, Kolkata

    Defence Sector-Army & Navy

    Indian Mountain Gun (MK-II)

    Gun Barrel

    Forged Armour Plates

    Turret Casting for T72 Tank

    Fabricated Hull & Turret for MBT Arjun

    Marine Diesel Engine Block

    Stern Gear Systems for INS RANA

    Rudder Stock Assembly

    Propeller Shaft Assembly

    Defence Sector-Ordnance Factories:

    Deep Boring CNC Machine (10 M) for IOF, Kanpur

    Horizontal Boring Machine for Naval Dockyard, Vishakhapatnam.

    Rolling Mill Equipment for Metal & Steel Factory, Ichapur

    Gun Barrel Drilling Machine

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    Manufacturing plan for nuclear grade steel forgings in 2010-11

    Besides this forging, HEC has also manufactured and supplied other forgings such as Rings, Flanges, Covers, and

    Plates to the nuclear energy sector.

    Recently, NPCIL placed an order for manufacture and supply of Tube Sheet, Nozzle and Cover forgings, as per

    material grade 20MnMoNi55. The first ingot for making the nozzles is scheduled for casting in Nov.2010. We are

    aiming to complete the supply by 3rd quarter of 2011. Also, seeing the demand for Shells of diameter beyond

    2500mm and Dish end forgings, we are going ahead with upgrading our facilities for the manufacture and supply of

    these forgings.

    The Heavy Machine Building Plant of HECL, has excellent facilities for machining and weld fabrication of large

    structures/assemblies. We propose to further upgrade the welding processes and facilities to conform to the

    requirements of nuclear pressure vessel fabrication in order to take up manufacture of equipments for nuclear power



    The results achieved showed that we had established the technological processes for achieving the required quality

    levels of steel forgings for nuclear power plant equipment. HEC understands that much bigger sizes of forgings are

    required for the commercial power plants. But, the Engineers in HEC are confident of taking up bigger challenges

    and help the country in import substitution. We are in the process of collaborating with established manufacturers,

    for upgradation of our facilities, to meet the demand for heavy steel forgings required for Pressurizer vessels, Steam

    Generators and Reactor Vessels.

    I take this opportunity in acknowledging the invaluable guidance and support provided by Sri R.S. Yadav, AD,

    RPG,BARC and his team of Engineers Sri R.N.Sen and Vivek Srivastav, in helping us in identifying the

    improvements in the processes, making a comprehensive manufacturing and quality assurance plan, upgradation of

    the testing processes and facilities and meticulous follow up of the processes. They have been a huge source of

    strength in overcoming various hurdles faced during development of the processes.