Alloy Steel Forgings Manufacturer in India: EN19, EN24, 4140, 4340 and 42CrMo4

October 7, 2026

Alloy steel forgings are made from steels containing chromium, molybdenum, nickel or vanadium, which allow them to be hardened and tempered to high strength while keeping toughness. EN19 (42CrMo4), EN24 (817M40), AISI 4140, AISI 4340 and 34CrNiMo6 are the most common grades for shafts, gears, couplings, hubs and high-strength structural parts. Selecting the right grade for the section size — and controlling heat treatment precisely — determines whether the part meets its mechanical properties

At a Glance: Alloy Steel Grades and Equivalents




Grade		Common EquivalentsKey AlloyingTypical Use
EN1942CrMo4, AISI 4140 (close), 709M40Cr-MoShafts, gears, medium sections
EN24817M40, close to AISI 4340, 40NiCrMoNi-Cr-MoHigh-strength shafts, heavier sections
AISI 413025CrMo4 (close)Cr-Mo, lower carbonOil & gas, weldable parts
AISI 434034CrNiMo6 (close), EN24 (close)Ni-Cr-MoAerospace, defence, heavy shafts
34CrNiMo6Close to 4340Ni-Cr-MoLarge crankshafts, rotors
300MModified 4340 with Si, VNi-Cr-Mo-Si-VLanding gear

Note: equivalents are approximate — chemistry ranges differ between standards. Always specify the governing standard on the purchase order.

Choosing a Grade by Section Size

Hardenability is the key reason to step up from EN19 to EN24 or 4340. In larger sections, a Cr-Mo steel such as EN19 may not harden through to the core after quenching, leaving lower strength at the centre. Ni-Cr-Mo grades such as EN24 and 4340 harden more deeply and are preferred for heavier sections where core properties matter.

Heat Treatment of Alloy Steel Forgings

Heat treatment in critical forgings

Most alloy steel forgings are supplied in the quenched and tempered (Q&T) condition. The key controls are:

  • Austenitising temperature and soak time matched to section size
  • Quench medium and agitation (oil or polymer)
  • Tempering temperature to hit the required strength and hardness band
  • Test location that reflects the section, such as a prolongation at the right depth

Over-tempering lowers strength; under-tempering risks brittleness. Furnace uniformity and calibration are essential.

Typical Alloy Steel Forged Components

  • Drive shafts, pinion shafts and step shafts
  • Gear blanks and ring gears
  • Couplings, hubs and flanges
  • Hydraulic cylinder rods and piston forgings
  • Torsion bars and defence components
  • Oil & gas tool bodies and mandrels

Testing and Certification

  • Chemical analysis per heat
  • Tensile, hardness and Charpy impact testing
  • Ultrasonic testing to ASTM A388 or EN 10228-3
  • MT for surface defects
  • EN 10204 3.1 / 3.2 certificates

Why Buyers Choose Vinir Engineering for Alloy Steel Forgings

Supply to Indian OEMs and exports to the US and Europe

Decades of experience in EN19, EN24, 4140, 4340, 4130 and 300M

Open die, closed die, ring rolling and radial forging in-house

Controlled quench and temper with calibrated furnaces

In-house CNC machining, NDT and NABL-accredited testing

AS9100D across all four manufacturing units

Request An Alloy Steel Forging Quote

Frequently Asked Questions

1.What is the difference between EN19 and EN24?+–
EN19 is a Cr-Mo steel; EN24 adds nickel, giving higher hardenability and toughness. EN24 is preferred for larger sections and higher strength requirements.
2.Is AISI 4140 the same as EN19 and 42CrMo4?+–
They are close equivalents but not identical — chemistry ranges differ slightly between standards. Specify the exact standard on your order.
3.Which alloy steel is best for heavy shafts?+–
For large sections, Ni-Cr-Mo grades such as EN24, 4340 or 34CrNiMo6 harden more deeply and are usually preferred.
4.Can alloy steel forgings be supplied finish machined?+–
Yes. Vinir supplies alloy steel forgings as-forged, rough machined or finish machined to drawing.
5.What hardness can be achieved on EN24 forgings?+–
It depends on the tempering temperature and section size. The required hardness band should be specified on the drawing or purchase order.