Alloy Steel dealers in UAE

AISI 4340 / EN24 / 817M40

AISI 4340 (36CrNiMo4, EN24, 817M40) — Ni-Cr-Mo ultra-high-strength alloy steel with exceptional toughness, deep hardenability, and fatigue resistance for oil & gas, aerospace, and heavy engineering.

Industries Served

Oil & Gas
Aerospace & Defense
Automotive
Petrochemical
Heavy Engineering
Power Generation
Marine
Mining

Applications

  • Large-diameter drill collars, subs, and heavyweight downhole tooling for UAE and GCC oilfield operations
  • Aircraft undercarriage legs, structural frames, and high-strength aerospace fasteners per AMS 6414 / AMS 6415
  • Heavy-duty drive shafts, crankshafts, and connecting rods for power generation and industrial machinery
  • Ring forgings for flanges, gear rings, and bearing races requiring deep through-hardening in large sections
  • Submarine and naval vessel structural components requiring high strength combined with toughness at depth
  • Motorsport and high-performance automotive crankshafts, gears, and suspension uprights
  • Pressure vessel shells and heavy-wall nozzles for upstream oil & gas and petrochemical applications
  • Mining equipment components including drill rods, excavator pins, and high-impact structural members
  • Large-section forged blocks and plates for tool and die bases requiring uniform hardness throughout
  • High-strength structural bolting and stud assemblies for critical bolted flanges in oil & gas installations

Chemical Composition

0.4 %
C

Carbon

0.38 – 0.43 %

0.25 %
Si

Silicon

0.15 – 0.35 %

0.7 %
Mn

Manganese

0.6 – 0.8 %

P

Phosphorus

≤ 0.025 %

S

Sulphur

≤ 0.025 %

0.8 %
Cr

Chromium

0.7 – 0.9 %

0.25 %
Mo

Molybdenum

0.2 – 0.3 %

1.82 %
Ni

Nickel

1.65 – 2 %

Typical value Range (min–max) Minimum (≥) Maximum (≤) Hover / tap for notes

Standard

ASTM A29 / A29M — current edition

Available Forms

Round Bar

Diameter range 25–600 mm. Hot-rolled standard; forged bar available for large diameters (>250 mm from forged bar stock). Ground/peeled bar on request. Applicable standards: ASTM A29, EN ISO 683-2, BS EN 10083-1. Standard stock condition Q&T; annealed and normalised on indent.

Plate

Thickness 25–500 mm; forged and rolled plate, cut-to-size. Q&T and annealed available. For large-section tooling bases, structural components, and aerospace forgings. Larger sections on request.

Block

Forged block, 25–500 mm thickness, cut-to-size. For large-section tooling bases and structural components requiring uniform hardness throughout. Larger sections on request.

Forging

Open-die and closed-die custom forgings. All sizes and weights on request. EN 10204 3.1 and 3.2 certified. Used for shafts, hubs, flanges, and aerospace structural components requiring deep hardenability. Lead times apply.

Ring Forging

Seamless rolled ring forgings in 4340, OD 100–2000 mm. Preferred form for flanges, bearing races, gear rings, and pressure vessel nozzles. Wall thickness and height per project requirement. EN 10204 3.1 and 3.2 certified. Lead times apply.

Designations & Equivalents

StandardDesignationNotes
AISI / SAEAISI 4340
DIN36CrNiMo4
EN / Werkstoff1.6511Werkstoff-Nr.
BS817M40BS / EN (UK)
BSEN24BS (legacy)
JISSNCM439
ASTMA29 Grade 4340
ASMESA-29 Grade 4340
UNSG43400
AMSAMS 6414 / AMS 6415bar & forging
Common NameMIL-S-5000MIL-SPEC designation

Compliance & Certification

StandardStatusNotes
EN 10204 3.1SuitableEN 10204 3.1 Mill Test Certificate provided as standard with all supply.
EN 10204 3.2ConditionalEN 10204 3.2 third-party inspection available on request.
NACE MR0175 / ISO 15156Requires ConfirmationCompliant when hardness controlled to 22 HRC (248 HB) max — specify at order stage; hardness confirmed on MTC.
NACE MR0103Requires ConfirmationFor H2S refinery environments under the same hardness criteria (max 22 HRC).

Specifications

Mechanical Properties

Values are minimums unless noted; hardness is a maximum.

PropertyAISI 4340 / EN24 / 817M40 — ASTM A29 / A29M — Quenched & Tempered (Q&T)DefaultAISI 4340 / EN24 / 817M40 — EN ISO 683-2 — AnnealedAISI 4340 / EN24 / 817M40 — EN ISO 683-2 — Normalised
Tensile Strength (UTS)range1000–1100 MPaTypical: 1050 MPaCondition: Room temp, longitudinalNotes: Per ASTM A29 / EN ISO 683-2. Values for 25–75 mm dia. bar. Larger sections may show slightly lower values.745 MPaTypical: 830 MPaCondition: Room temp, longitudinalNotes: Per EN ISO 683-2 annealed condition.860 MPaTypical: 960 MPaCondition: Room temp, longitudinalNotes: Normalised 4340 has higher UTS than normalised 4140 due to Ni-Cr-Mo alloy content.
Yield Strength (0.2% Proof Stress)range860–970 MPaTypical: 910 MPaCondition: Room temp, longitudinalNotes: 0.2% offset method.470 MPaTypical: 560 MPaCondition: Room temp, longitudinal600 MPaTypical: 700 MPaCondition: Room temp, longitudinal
Elongationmin12 %Typical: 14 %Condition: 50 mm gauge lengthNotes: Minimum 12% per EN ISO 683-2 Q&T.15 %Typical: 19 %Condition: 50 mm gauge length12 %Typical: 16 %Condition: 50 mm gauge length
Reduction of Areamin45 %Typical: 55 %Condition: LongitudinalNotes: Minimum 45%.45 %Typical: 55 %Condition: Longitudinal40 %Typical: 50 %Condition: Longitudinal
Hardnessrange285–341 HBTypical: 310 HBCondition: Surface, BrinellNotes: Approx. 30–36 HRC. NACE MR0175 requires max 22 HRC (248 HB).197–235 HBTypical: 215 HBCondition: Surface, BrinellNotes: Higher than 4140 annealed due to Ni. Carbide tooling recommended.250–300 HBTypical: 275 HBCondition: Surface, BrinellNotes: Higher than 4140 normalised. Not recommended for extensive machining without further annealing.
Impact Energy (Charpy)min50 JTypical: 68 JCondition: Room temp, V-notchNotes: Longitudinal. Superior toughness vs 4140 at equivalent hardness. [VERIFY — values vary by section and temper temp]Notes: Not typically specified for annealed condition.Notes: Not typically specified for normalised condition.

Physical Properties

PropertyAISI 4340 / EN24 / 817M40 — ASTM A29 / A29M — Quenched & Tempered (Q&T)DefaultAISI 4340 / EN24 / 817M40 — EN ISO 683-2 — AnnealedAISI 4340 / EN24 / 817M40 — EN ISO 683-2 — Normalised
Density20°C7.85 g/cm37.85 g/cm37.85 g/cm3
Modulus of Elasticity25°C210 GPa210 GPa210 GPa
Thermal Conductivity100°C44.5 W/m·K44.5 W/m·K44.5 W/m·K
Coefficient of Thermal Expansion20–100°C12.3 um/m·°C12.3 um/m·°C12.3 um/m·°C
Specific Heat Capacity20°C475 J/kg·K475 J/kg·K475 J/kg·K
Melting Point / RangeSolidus1410 °C1410 °C1410 °C
ENGINEERING NOTES
Weldability
Fair

4340 / 36CrNiMo4 requires careful welding procedures due to its high alloy content and carbon equivalent (typically 0.85–0.95 CE). Preheat to 200–315°C is mandatory for all section sizes. Post-weld heat treatment (PWHT) at 580–650°C for a minimum of 2 hours per 25 mm section is essential to prevent hydrogen-induced cracking and restore toughness in the heat-affected zone. Weld only in the annealed or low-hardness normalised condition — never weld Q&T material at full hardness without tempering first. Use low-hydrogen consumables exclusively. Allow slow, controlled cooling after PWHT; never quench after stress relief. For aerospace applications, follow applicable MIL-HDBK-5 or AMS welding procedures. Recommended consumables: ER100S-G for TIG (GTAW) and MIG (GMAW); E10018-G low-hydrogen stick electrode for SMAW (E9018-G where post-weld toughness is prioritised over strength match).

Machinability
Fair

Best machined in the annealed condition (approx. 197–235 HB) using HSS or carbide tooling. In Q&T condition (285–341 HB), carbide tooling with reduced cutting speeds is mandatory. Machinability approximately 55% of AISI 1212 free-machining steel — lower than 4140 due to higher alloy content and nickel. Rough machine before final heat treatment; finish machine after Q&T to minimise distortion in close-tolerance components.

Overview

AISI 4340 (DIN 36CrNiMo4, Werkstoff-Nr. 1.6511, BS 817M40, legacy EN24) is a nickel-chromium-molybdenum ultra-high-strength low-alloy steel, alloyed with 1.65–2.00% nickel, 0.70–0.90% chromium, and 0.20–0.30% molybdenum. The nickel addition distinguishes 4340 from the simpler Cr-Mo grades — it provides significantly greater toughness at high hardness levels, superior hardenability enabling through-hardening in sections up to 150 mm diameter, and excellent fatigue resistance under cyclic loading. In the quenched and tempered condition, 4340 routinely achieves tensile strengths of 1000–1100 MPa with Charpy impact values of 50–80 J at room temperature — performance that makes it the benchmark alloy steel for large-section downhole tools, aircraft undercarriage, heavy drive shafts, and critical structural forgings globally.

Nifty Alloys supplies AISI 4340 / 36CrNiMo4 from stock in Dubai, UAE, in round bar, plate/block, forgings, and ring forgings across a wide range of sizes. All material is supplied with EN 10204 3.1 Mill Test Certificates as standard — confirming chemical composition, mechanical properties, and full traceability to mill source. EN 10204 3.2 third-party inspection is available on request for critical project and aerospace applications. We deliver across the UAE within 24–48 hours and export to Saudi Arabia, Kuwait, Qatar, Oman, and Bahrain. Contact our team for same-day quotation and stock availability.

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AISI 4340 (EN24 / 817M40) is the benchmark ultra-high-strength alloy steel for applications requiring maximum toughness in large sections. Key applications include large-diameter drill collars and downhole tooling for UAE and GCC oilfield operations; aircraft undercarriage legs and structural aerospace components per AMS 6414 / AMS 6415; heavy-duty drive shafts, crankshafts, and gear shafts for power generation and industrial machinery; ring forgings for flanges, gear rings, and bearing races; pressure vessel components in upstream oil & gas; and high-strength structural bolts and studs for critical flanged connections. Its superior toughness vs 4140 — particularly in sections above 100 mm — makes it the specified grade wherever standard Cr-Mo steels cannot deliver sufficient impact resistance or hardenability depth.

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