Land Defence Forging in India: Components, Materials, and Standards for Ground Combat Platforms
Land defence forging covers forged components for all ground combat and support platforms — main battle tanks, infantry fighting vehicles, armoured personnel carriers, self-propelled artillery, towed gun systems, logistic vehicles, and engineer equipment. India’s land forces operate one of the largest mechanised fleets in the world, creating sustained demand for forged components across new production, mid-life upgrade, overhaul, and spares programmes running simultaneously.
Land Defence Platform Categories and Their Forging Requirements
| Platform | Managed By | Primary Forging Categories | Volume Profile |
| Arjun MBT Mk1A | CVRDE / HVF Avadi | Hull structure, gun system, drivetrain, running gear | Low — 120 units/year max |
| T-90S Bhishma | HVF Avadi | Drivetrain, suspension, hull fittings — indigenisation | Medium — 100–200 units/year |
| BMP-II Sarath | OFB / AVNL Medak | Complete drivetrain, suspension, access components | Medium — fleet maintenance |
| K9 Vajra SPH | L&T / Hanwha | Howitzer barrel blank, recoil system, gun mount | Low — 100 units order |
| Dhanush Howitzer | OFB / Gun Carriage Factory | Gun barrel forging, breech ring, carriage structure | Low — spares and production |
| ATAGS | DRDO / OFB | Advanced gun barrel, auto-loader components | Development stage |
| MRAP / Protected Vehicles | Tata, Mahindra, Force | Axle, suspension knuckle, structural cross-members | Medium — 200–500 units/year |
| Bridge Laying Tanks | BEML | Structural and hydraulic system forgings | Very low — niche |
Artillery Forgings: The Most Demanding Land Defence Category
Artillery gun barrel forgings are among the most technically demanding in the entire land defence forging supply chain. The requirements combine:
- High-strength chrome-molybdenum steel (typically 25CrMo4, 30CrNiMo8, or equivalent) for tensile strength exceeding 900 MPa at operating temperature
- Extremely tight bore dimensional tolerances — the rifled bore must be concentric with the outer profile to within fractions of a millimetre across the full barrel length
- 100% ultrasonic testing through the full barrel cross-section to verify internal cleanliness — any inclusion, pipe, or void is a rejection
- Proof pressure testing of the completed barrel before acceptance
Gun Barrel Manufacturing Process
The barrel blank is forged from a large ingot — typically 2,000–5,000 kg for a 105mm or 155mm artillery gun — using open die forging with a saddle support to maintain concentricity during elongation. The forging sequence must achieve adequate reduction ratio through the wall section to refine grain structure and eliminate ingot segregation. After forging the blank is rough-bored to allow access for comprehensive UT, with final machining and rifling performed after acceptance.
K9 Vajra and Dhanush Programme Requirements
The K9 Vajra self-propelled howitzer — manufactured by L&T under technology transfer from Hanwha of South Korea — uses a 155mm 52-calibre barrel. L&T’s forging supply chain for K9 is managed under AS9100D with Korean OEM quality requirements overlaid. Dhanush, the indigenous 155mm howitzer developed from the Bofors FH-77 design, is manufactured at the Gun Carriage Factory with DGQA oversight.
Tank and IFV Drivetrain Forgings
Main Battle Tank Drivetrain
An MBT drivetrain contains 40–60 distinct forged components including:
Final drive gears and housings — forged in case-hardening steels (EN36, 18CrNiMo7-6) requiring carburising heat treatment after forging to develop a hard wear-resistant surface over a tough core. Dimensional accuracy at gear tooth roots is critical.
Drive shaft forgings — solid and hollow shafts in EN24 or 4340 alloy steel, forged to near-net shape with machining allowance. Hollow shafts may be produced by radial forging or by piercing on the open die press.
Sprocket assemblies — the drive sprocket engages the track and must withstand high cyclic impact loads. Forged in alloy steel with controlled surface hardness after heat treatment.
BMP-II Sarath Drivetrain
The Sarath’s drivetrain uses a torsional transmission system with specific Russian-origin alloy steel grades (30KhGSNA, 38KhMYuA) for key components. Indigenisation requires demonstrating equivalency between Russian grades and international or Indian equivalents — 4340 and 35NiCrMoV12 are common equivalents. AVNL manages these indigenisation programmes with DGQA oversight.
Wheeled Protected Vehicle Forgings: The Growing Category
India’s expanding fleet of wheeled protected vehicles — produced by Tata Defence, Mahindra Defence, and Force Motors — represents the fastest-growing land defence forging market segment in India. These vehicles use:
Axle and hub forgings — heavy-duty axle beam forgings and wheel hub forgings in alloy steel, carrying gross vehicle weights of 12–25 tonnes over rough terrain. Fatigue life requirements are severe — field conditions include washboard roads, obstacle crossing, and mine blast events.
Suspension knuckle forgings — steering knuckles and suspension upright forgings in high-strength alloy steel. These are safety-critical components — failure causes loss of vehicle control. 100% MT and UT inspection is standard.
Structural cross-member forgings — hull frame connection forgings, mine plate attachment forgings, and blast deflector attachment structures. These must absorb and redirect mine blast energy without fracturing.
Private sector OEMs managing these programmes maintain their own AS9100D-certified supply chains and qualify forging suppliers through their own internal vendor assessment processes, supplemented by DGQA oversight where the end-customer is the Indian Army.
Materials Used in Land Defence Forgings
Standard Alloy Steels
EN24 (817M40), EN36 (655M13), 4340, 4130, EN19 — the workhorses. High strength, good toughness, excellent response to quench and temper. Used across drivetrain, suspension, and structural applications.
Case-Hardening Steels
EN36 (655M13), 18CrNiMo7-6 — used where wear resistance at the surface is critical alongside toughness in the core. Final drive gears, sprocket teeth, bearing races. Carburising or carbonitriding heat treatment after forging develops the hardened case.
Spring Steels
45CrNiMoVA, 51CrV4 — torsion bars and suspension springs. Must achieve very high yield strength (above 1,400 MPa) with adequate fatigue life under reversed torsional loading. Heat treatment precision is critical — over-tempering reduces strength, under-tempering reduces toughness.
High-Hardness Armour Steels
ARMOX 500T, ARMOX 600T, Miilux 400, RAMOR 500 — for hull, turret, and protective structure forgings. Tight forging temperature window, controlled reduction ratios, post-forge through-hardness verification.
Aluminium Alloys
7075-T6 and 2024-T4 for weight-sensitive secondary components on lighter wheeled platforms — access hatches, mounting brackets, secondary structural members where blast resistance is less critical than weight reduction.
Quality Standards for Land Defence Forgings
AS9100D is the primary quality management requirement. Tata, L&T, Mahindra, and international OEMs with Indian programmes (Hanwha for K9, Elbit for various upgrade programmes) all require AS9100D from their forging supply chains.
DGQA oversight applies across all Indian Army procurement — both DPSU-manufactured platforms and private sector OEM platforms supplied under Indian Army contracts. DGQA source inspection at the forging supplier’s facility is standard for new supplier qualifications and ongoing lot acceptance.
OFB / AVNL quality plans for components entering Ordnance Factory production lines include additional requirements — specific material test frequencies, mandatory witness hold points at forging and heat treatment stages, higher NDT sampling rates.
Platform-specific standards — the Arjun programme references CVRDE-developed specifications. The K9 programme references Korean military standards alongside Indian requirements. The T-90 programme references Russian GOST standards for certain legacy components. Suppliers must identify which standards apply and ensure their processes and test methods align.
Batch Sizes and Production Profiles in Land Defence
Understanding the volume profile is essential for forging suppliers considering land defence programmes. Most are characterised by:
Low peak volumes — even active production programmes rarely exceed 500 components per year per part number. MBT production at HVF Avadi runs at approximately 8–15 vehicles per month at peak, generating modest forging volumes per part.
Long spares tail — the Sarath has been in Indian service since the 1980s. Spares demand will continue for another 20–30 years regardless of new platform inductions. This creates a long-duration, low-volume requirement that favours established, stable suppliers.
Unpredictable call-offs — defence procurement schedules are driven by budget availability, not manufacturing logic. A forging supplier must be able to respond to a call-off after 6–12 months of silence and restart production to the same quality level without a new qualification cycle.
This profile makes high-mix low-volume capability and documented process control — not just production capacity — the critical capability differentiators.
Vinir Engineering’s Land Defence Forging Capability
Vinir’s capability covers the full weight range of land defence forgings — 10 kg for small drivetrain fittings through to 15,000 kg for large structural open die forgings. Closed die forging on 1T to 12T hammers and a 3000T press handles the majority of drivetrain, suspension, and artillery component requirements. Ring rolling to Ø4,500mm covers turret ring forgings for all current MBT-class vehicles. Open die capability on the 3000T press with dango manipulators handles gun barrel blanks, large structural forgings, and heavy shaft forgings.
In-house heat treatment includes quench and temper for alloy steels, normalising, and solution annealing for stainless and duplex grades. NABL-accredited testing covers tensile, Charpy impact, Brinell and Vickers hardness, and chemical analysis — all required for land defence forging acceptance under DGQA oversight.
AS9100D certification is maintained across all four manufacturing units. IBR and ABS certifications cover programme requirements that extend beyond standard land vehicle applications into naval and nuclear supply.
Frequently Asked Questions — Land Defence Forgings India
What certifications are required to supply forgings to Indian Army programmes?
AS9100D is the primary quality management certification expected by OEMs and DPSUs serving Indian Army programmes. DGQA approval or registration is required for components entering Indian Army acceptance inspection — this applies regardless of whether the immediate customer is a DPSU, a private sector OEM, or a system integrator. For programmes involving artillery or armoured vehicle main armament, DGQA oversight is intensive and includes source inspection at the forging supplier’s facility.
How are Russian material grades replaced in T-90 indigenisation programmes?
Russian GOST material grades used in T-90 components have established equivalents in international and Indian standards. 30KhGSNA (Russian) is broadly equivalent to 4340 (AISI) or 34CrNiMo6 (EN). 38KhMYuA is broadly equivalent to 38CrMoAl (nitriding steel). The equivalency must be demonstrated through comparative mechanical testing — producing forgings in both the original Russian grade and the proposed Indian equivalent and comparing tensile, impact, and hardness results. DGQA and the OEM both review the comparative data before approving the substitution.
What is the minimum press capacity needed for artillery gun barrel forgings?
A 155mm artillery gun barrel blank weighs approximately 2,000–3,500 kg after forging and requires a minimum press capacity of 3,000 tonnes to achieve adequate reduction in the wall section. A dango manipulator or similar manipulator is required to support and rotate the blank during elongation forging. Adequate working space between the press columns must accommodate the 4–6 metre length of a 155mm barrel blank.
How do land defence forging suppliers handle unpredictable call-off schedules?
Experienced land defence forging suppliers maintain documented process records — forge plans, heat treatment procedures, NDT procedures — that allow restarting production after extended gaps without a new qualification cycle. Critical dies are maintained in serviceable condition between call-offs. Raw material sourcing from approved mills is pre-arranged to avoid lead time surprises when a call-off arrives. The ability to restart production within 4–6 weeks of a call-off, with the same quality level as the previous delivery, is a key differentiator for sustained land defence supply relationships.
Why do land defence programmes prefer single-source forge-to-finish suppliers?
Land defence programmes are often managed with limited procurement resources — DGQA inspection capacity, OEM quality team bandwidth, and procurement administration. A single forge-to-finish supplier — one AS9100D quality system, one set of process records, one source inspection visit covering all operations — is significantly easier to manage than a multi-supplier arrangement where forging, heat treatment, and machining are split between three separate companies. Single-source supply also eliminates inter-company traceability handoffs that create documentation risks under DGQA review.
