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AISI 4340 Bolts Manufacturer & Exporter in India

Explore AISI 4340 Bolts Manufacturer & Exporter in India manufactured for demanding industrial applications with reliable strength, corrosion resistance and compliance with international standards.
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-196

Min Temp

870

Max Temp

🌡

870

Suitable for continuous service up to approximately 870°C under typical operating conditions.

⚡

620

Typical tensile strength around 620 MPa depending on product form and heat treatment.

🛡

Very Good

Very Good corrosion resistance in a wide range of industrial environments.

⚖

8

Typical density is approximately 8.0 g/cm³.

Product Overview

What are AISI 4340 Bolts?

AISI 4340 bolts are high-strength alloy steel fasteners manufactured from chromium-nickel-molybdenum steel conforming to ASTM A193 Grade B16 or equivalent. This alloy is renowned for its exceptional toughness, fatigue resistance, and high tensile strength, making it ideal for critical bolted joints subjected to heavy loads and dynamic stresses.

Through heat treatment (quenching and tempering), AISI 4340 bolts achieve tensile strengths exceeding 930 MPa, with excellent ductility and impact resistance even at low temperatures. These bolts are widely specified in aerospace, oil & gas, and heavy engineering applications where superior mechanical performance is essential.

Quick Specifications

MaterialAISI 4340 Alloy Steel
UNS NumberG43400
DIN Number1.6565
Material StandardASTM A193 Gr B16 / ASTM A322
Bolt Standard (Metric)DIN 931 / DIN 933 / ISO 4014
Bolt Standard (Inch)ASME B18.2.1
Thread FormISO Metric / UNC / UNF
Diameter RangeM6-M100 / ¼"-4"
Tensile Strength930-1080 MPa (135-157 ksi)
Yield Strength785 MPa (114 ksi) min
Hardness28-36 HRC
? All material certified by NABL-accredited laboratory. Heat treatment and mechanical test reports available on request.

Complete the Fastener Set

Other AISI 4340 Fastener Products Available from RealBolt

RealBolt also manufactures the complete AISI 4340 fastener range from certified alloy steel bar stock, including AISI 4340 Nuts, AISI 4340 Screws, AISI 4340 Washers, AISI 4340 Studs, and AISI 4340 Threaded Rods. All AISI 4340 fastener types are produced to ASTM with full EN 10204 MTC 3.1/3.2 documentation.
AISI 4340 Nuts
AISI 4340 Screws
AISI 4340 Washers
AISI 4340 Studs
AISI 4340 Threaded Rods

Technical Data

AISI 4340 Bolts Dimensions, Sizes & Thread Standards

AISI 4340 Bolts are available in metric M6–M100 and inch ¼″–4″ as standard. Per DIN 931 (partial thread) / DIN 933 (full thread) / ISO 4014. Custom lengths in 5mm increments. Inch dimensions available per ASME B18.2.1. All AISI 4340 bolts dimensions are verified against applicable DIN, ISO, and ASME

Hex Bolt Dimensions - Metric (DIN 931 / ISO 4014)

Size (M)Pitch (mm)A/F (mm)Head Ht (mm)Min L (mm)Max L (mm)
M61.0104.010200
M81.25135.312250
M101.5176.416300
M121.75197.520400
M162.02410.025500
M202.53012.530600
M243.03615.040600
M303.54618.750800
M364.05522.5601000
M424.56526.0801000
M485.07530.01001200
M565.58535.01201500
M646.09540.01402000
M726.010545.01602000
M806.011550.01802500
M1006.014563.02003000

Dimensional & Material Standards

StandardCoversThread
DIN 931Hex bolts, partial threadMetric
DIN 933Hex bolts, full threadMetric
ISO 4014Hex head screws, partialMetric
ISO 4017Hex head screws, fullMetric
ASME B18.2.1Hex & heavy hex boltsUNC/UNF
ASME B16.5Stud bolts for flangesUNC
MSS SP-75Stud bolts, high-pressureUNC
Material StandardRequirement
ASTM A193 Gr B16Bar/rod - AISI 4340
ASTM A322Alloy steel mechanical
EN 10269Mechanical properties
EN 10204 3.1Mill test certificate
EN 10204 3.2TPI-witnessed MTC

Material Chemistry

AISI 4340 Chemical Composition

AISI 4340 Bolts are produced from medium-carbon or alloy steel with carbon (0.15–0.55%), chromium, manganese, and boron additions controlled per ASTM and ISO 898-1. Carbon content and quench-and-temper heat treatment are the primary strength levers, delivering proof loads from 580 MPa (Class 8.8) to 970 MPa (Class 12.9).

Chemical Composition per ASTM A193 Gr B16 / AISI 4340

ElementComposition (%)
Carbon (C)0.38-0.43
Manganese (Mn)0.60-0.80
Silicon (Si)0.15-0.30
Nickel (Ni)1.65-2.00
Chromium (Cr)0.70-0.90
Molybdenum (Mo)0.20-0.30
Phosphorus (P)0.035 max
Sulfur (S)0.040 max
Iron (Fe)Balance
? All heats verified by NABL-accredited spectrometry. Chemical test reports available on request.

Why AISI 4340 Alloy Composition Matters for Bolts

Ni (1.65–2.00%) — Toughness & Hardenability
Nickel content in AISI 4340 enhances toughness and deep hardenability, ensuring uniform mechanical properties throughout large-diameter bolts and studs.
Cr (0.70–0.90%) — Wear & Corrosion Resistance
Chromium improves surface hardness and provides moderate resistance to oxidation and mild corrosion, extending bolt service life in demanding environments.
Mo (0.20–0.30%) — High-Temperature Strength
Molybdenum increases creep resistance and maintains bolt strength at elevated temperatures, making AISI 4340 bolts suitable for turbine, engine, and pressure vessel applications.

Fastener Performance

AISI 4340 Bolts Mechanical Properties & Torque Reference

The table below lists mechanical properties and torque reference for AISI 4340 Bolts per ASTM. AISI 4340 bolts achieve 620 MPa tensile strength, with hardness, yield, and elongation values verified by NABL-accredited testing and reported in the EN 10204 MTC.

Bolt SizeDry (Nm)Lubricated (Nm)Clamp Load (kN)
M121209645
M1629523690
M20580464140
M241000800200
M3020001600320
M3635002800460
M4254004320630
M4878006240850
?? Anti-galling: Use molybdenum-based or graphite anti-seize. Lubricated values assume K=0.16. Avoid copper-based anti-seize in high-temperature or hydrogen service.

Industry Applications

AISI 4340 Bolts Applications — Industries & End Uses

AISI 4340 Bolts from RealBolt are specified across structural engineering, automotive, machinery, and pressure vessels where very good corrosion resistance and 620 MPa tensile strength are required for reliable fastener performance. Click each industry below for detailed application examples. Select an industry below to see specific AISI 4340 bolts application details and RealBolt stock availability.
AISI 4340 bolts are widely used for high-pressure vessel closures, wellhead flanges, and BOP stacks in upstream oil & gas. Their high strength and impact resistance make them ideal for critical bolted joints in sour and non-sour service.
Hex bolts and heavy hex bolts for mining equipment, draglines, crushers, and mill liners where shock loading and fatigue are common. AISI 4340’s toughness ensures reliable performance in harsh, abrasive environments.
Turbine casing bolts, HRSG flange bolts, and boiler stud bolts where high tensile strength and creep resistance are required at elevated temperatures. AISI 4340 bolts are specified for steam and gas turbine assemblies.
AISI 4340 bolts are used in landing gear, engine mounts, and structural assemblies in aircraft and defense vehicles, where high strength-to-weight ratio and fracture toughness are critical. Supplied to AMS 6415 and equivalent standards.

AISI 4340 Bolts Standards & International Certifications

AISI 4340 Bolts from RealBolt Engineering Industries are manufactured to internationally recognised fastener dimensional standards covering thread form, tolerances, strength grades, and quality requirements. Every batch ships with EN 10204 MTC 3.1/3.2, hardness test certificate, dimensional inspection report, and proof load test records — available on request for all orders.
Standards
DIN 931 DIN 933 DIN 960 DIN 961 DIN 6914 ISO 4014 ISO 4017 ISO 8676 ISO 8765 ASME B18.2.1 EN 14399 EN 15048 EN ISO 4014 EN ISO 4017 BS EN ISO 4014 BS 3692 BS 4190 IS 1363 IS 1364 IS 3757 SAE J429 UNI 5737 UNI 5739 CSN 021101 PN 82101
Certifications
ISO 9001:2015EN 10204 3.1/3.2PED 2014/68/EUNABL Lab

Buy AISI 4340 Bolts from India's Leading Manufacturer — Get a Competitive Quote Today

Partner with RealBolt — India’s leading manufacturer of certified AISI 4340 Bolts — for competitive pricing, EN 10204 MTC 3.1/3.2 documentation, and fast Mumbai dispatch. Standard sizes are ex-stock; custom dimensions accepted with 2–3 week lead time. Request your quote today.
022-6743-7972
+91 90226 36025
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Answers for Buyers

AISI 4340 Bolts — Frequently Asked Questions

Browse expert answers to common questions about AISI 4340 Bolts from RealBolt — covering property class, tensile and proof load, galvanizing embrittlement risk, surface finishes, and dimensional certification. Contact our technical team directly for project-specific guidance on AISI 4340 bolts selection and pricing.
AISI 4340 hex bolts are available to DIN 931 (metric partial thread), DIN 933 (metric full thread), ISO 4014/4017, and ASME B18.2.1 (inch hex and heavy hex). Stud bolts are supplied per ASME B16.5 or MSS SP-75 for flange applications. Custom thread forms (BSW, BSF, Whitworth, BSPP) are available on request with 2-3 week lead time.
Use molybdenum-based or graphite anti-seize compound (such as Molykote 1000 or Loctite LB 8008). Apply to threads and nut bearing face. Reduce torque values by 20% vs dry assembly. Avoid copper-based anti-seize in hydrogen or high-temperature service to prevent embrittlement or galvanic corrosion.
AISI 4340 bolts are suitable for continuous service up to 450°C. For higher temperatures, consider ASTM A193 B7M or B16, or consult for alternative alloys. Always verify mechanical properties after heat exposure for critical applications.
No formal MOQ for standard sizes (M12-M36) held ex-stock – we supply from single pieces for urgent maintenance. Custom sizes have an MOQ of 10 kg minimum. Flange stud bolt sets are supplied by the set with no minimum. Quantity price breaks at 50 pcs, 200 pcs, and 500 pcs.

Industrial Cities We Serve:

  • Ahmedabad
  • Aurangabad
  • Bengaluru
  • Chennai
  • Coimbatore
  • Faridabad
  • Gandhidham
  • Greater Noida
  • Gurugram
  • Hazira
  • Hosur
  • Hyderabad
  • Jamnagar
  • Jamshedpur
  • Ludhiana
  • Mumbai
  • Mundra
  • Mysuru
  • Nagpur
  • Nashik
  • Navi Mumbai
  • Noida
  • Pune
  • Rajkot
  • Sanand
  • Surat
  • Thane
  • Tiruppur
  • Vadodara
  • Visakhapatnam

Countries We Export To:

  • US
  • Canada
  • Mexico
  • Germany
  • UK
  • France
  • Italy
  • Spain
  • Netherlands
  • Belgium
  • Poland
  • Sweden
  • Norway
  • Denmark
  • Turkey
  • UAE
  • Saudi Arabia
  • Qatar
  • Oman
  • Kuwait
  • Bahrain
  • South Africa
  • Egypt
  • Nigeria
  • Australia
  • New Zealand
  • Singapore
  • Malaysia
  • Indonesia
  • Thailand
  • Vietnam
  • South Korea
  • Japan
  • Brazil