Metric Grade 8.8 Fasteners Manufacturer & Exporter in India

Metric Grade 8.8 fasteners are medium-carbon steel fasteners heat-treated to deliver reliable tensile strength and consistent clamping force. We manufacture Grade 8.8 fasteners for structural, automotive, machinery, and general engineering applications.

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Products

-50°C

Min Temp

150°C

Max Temp

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150°C

Recommended service limit for ISO 898-1 property class 8.8 fasteners · mechanical properties not intended for use above 150°C

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800 MPa

Minimum tensile strength for Metric Grade 8.8 bolts, screws and studs · yield strength approximately 640 MPa

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Low

Plain carbon/alloy steel offers limited corrosion resistance unless zinc plated, hot-dip galvanized, phosphate coated or otherwise protected

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7.85 g/cm³

Typical density of quenched and tempered carbon steel fasteners

What is Metric Grade 8.8?

ISO 898-1 Property Class 8.8 is the global standard medium-high strength bolt specification, equivalent to ASTM A325 in the United States. Made from medium-carbon steel or alloy steel, quenched and tempered for ≥25mm diameter, with tensile strength 800 MPa minimum and yield (0.2% proof) 640 MPa minimum. Class 8.8 hex bolts and stud bolts are the most widely used industrial fastener specification globally — used in general machinery, automotive powertrain, construction equipment, marine structures and all industrial equipment requiring medium-high strength bolting. Matched with ISO 898-2 Class 8 hex nuts.
PropertyValue
StandardISO 898-1 / DIN 267
Tensile Strength800 MPa min
Yield Strength640 MPa min
Hardness22–32 HRC
Core MaterialMedium Carbon Steel, Quenched & Tempered
Corrosion RatingModerate (Zinc/Yellow Plated)

Metric Grade 8.8 Fastener Products

RealBolt manufactures Metric Grade 8.8 fasteners including hex bolts, heavy hex bolts, studs, threaded rod, nuts, washers, socket cap screws, and custom-machined specials from certified Metric Grade 8.8 (Medium Carbon Q&T) bar stock. All Metric Grade 8.8 fasteners are produced to order and inspected to relevant ISO 898-1 material standards.
ElementComposition (%)
C0.15–0.40
Mn0.50–1.40
P≤0.035
S≤0.035
Cr+Mo+Nias req. for hardenability

Chemical Composition of Metric Grade 8.8 Fasteners

Metric Grade 8.8 fasteners are manufactured from medium carbon steel, typically alloyed with controlled levels of carbon, manganese, and boron to enhance hardenability and strength. Carbon content, usually between 0.28% and 0.55%, provides the primary strengthening mechanism through quench and temper heat treatment. Manganese improves hardenability and tensile strength while boron, when added, further refines grain structure and boosts core strength in smaller diameters, ensuring consistent mechanical performance across production batches.

The quenched and tempered microstructure delivers a superior balance of tensile strength, yield strength, and ductility, making Grade 8.8 fasteners ideal for structural, automotive, and machinery applications requiring high clamping loads. Zinc or other protective platings enhance corrosion resistance against atmospheric conditions, while the material maintains reliable performance up to moderate service temperatures. This combination of strength, toughness, and cost-effectiveness makes Grade 8.8 fasteners a preferred choice for demanding engineering assemblies worldwide.

Specifications

Metric Grade 8.8 Fastener Specifications

Metric Grade 8.8 Fasteners are high-strength metric components defined by their mechanical properties, dimensional specifications, and technical data for reliable structural performance. Suitable for precision assembly, they combine standardized sizing with strength characteristics that support demanding fastening applications across industrial and mechanical systems.

Mechanical Properties — Annealed Condition

PropertyValue
Tensile Strength800 MPa min
Yield Strength640 MPa min
Elongation12% min
Hardness22–32 HRC
Modulus of Elasticity200 GPa
Thermal Expansion11.5 x10⁻⁶/°C
Density7.85 g/cm³
Melting Range1420–1460°C
Heat TreatmentQuenched & Tempered
Max Service Temperature300°C

Available Dimensional Standards

StandardDetails
Bolt StandardISO 4014 / ISO 4017
Stud Bolt StandardDIN 976 / ASTM A193 equivalent
Nut StandardISO 4032 / ISO 4033
Washer StandardISO 7089 / ISO 7090
Thread FormMetric Coarse & Fine (ISO 261/262)
Diameter RangeM3 – M100
Length Range10mm – 500mm
Product FormsBolts, Studs, Nuts, Washers, Screws
Custom SizesAvailable on Request
Inspection StandardsEN 10204 3.1 / 3.2

Applications

Metric Grade 8.8 Fastener Applications

Metric Grade 8.8 Fasteners from RealBolt Engineering Industries are specified wherever corrosion resistance, elevated-temperature strength, or chemical media compatibility is critical to fastener performance. Primary industries and end-uses for Metric Grade 8.8 fasteners include most common metric fastener; general engineering, machinery.
Metric Grade 8.8 bolts are widely used in bolted steel frames, brackets, base plates, guards, platforms and fabricated equipment where higher clamp load is needed than lower property classes can provide.
The 800 MPa tensile strength class makes Grade 8.8 fasteners suitable for pumps, conveyors, gearboxes, machine bases, agricultural equipment and production machinery subject to vibration and repeated service loads.
Metric Grade 8.8 screws and bolts are commonly specified in chassis brackets, engine accessories, suspension-adjacent components, trailers and commercial vehicle assemblies where controlled tightening and reliable fatigue performance are important.
Because Grade 8.8 is a globally recognized ISO property class, it is a practical choice for MRO replacements and OEM builds requiring consistent metric thread compatibility, predictable proof load and broad availability in many head styles and finishes.
Traceable & Certified

Metric Grade 8.8 Fasteners — Standards, Certifications & Test Reports

Metric Grade 8.8 fasteners are manufactured and tested to internationally recognised material and dimensional standards, including ISO 898-1 Class 8.8, EN ISO 4014, EN ISO 4017, DIN 933. RealBolt Engineering Industries supplies Metric Grade 8.8 (Medium Carbon Q&T) fasteners with full material test reports (MTRs), mill certificates, and third-party inspection to confirm compliance with your project specifications.

Need ISO Class 8.8 fasteners? Get a competitive price today.

Partner with RealBolt Engineering Industries for certified Metric Grade 8.8 fasteners backed by full MTRs, competitive pricing, and reliable delivery. Our technical team is available to help you select the right Metric Grade 8.8 (Medium Carbon Q&T) bolts, studs, nuts, and washers for your application — whether standard sizes or custom-machined specials.
Answers for Buyers

Frequently Asked Questions About Metric Grade 8.8 Fasteners

Browse the questions below to get quick, expert answers about Metric Grade 8.8 Fasteners — covering alloy specifications (Medium Carbon Q&T), applicable standards (ISO 898-1), temperature ratings, corrosion performance, and how to source certified Metric Grade 8.8 fasteners from RealBolt Engineering Industries.
The first digit (8) indicates 1/100 of the minimum tensile strength = 800 MPa. The second digit (8) indicates 8/10 of the tensile = 80% ratio of yield to tensile = 640 MPa minimum yield. Property class 8.8 = 800 MPa tensile, 640 MPa yield.
Approximately 195 Nm for M16 Class 8.8 in lightly oiled condition (friction coefficient µ = 0.12). For dry (unlubricated), multiply by 1.25. For Molykote-lubricated, divide by approximately 1.5. Always verify torque with the equipment supplier’s specification — joint compliance and friction variation affect actual preload significantly.
Yes — Class 8.8 (800 MPa) is generally safe to galvanise per ISO 10684, provided: (1) acid pickling time is minimised, (2) galvanising temperature ≤570°C, (3) hydrogen embrittlement relief bake (200°C/24h) is performed after galvanising. Always verify with galvaniser.
ISO 898-2 Class 8 hex nuts are the matched nut for Class 8.8 bolts. For heavy hex applications (flange bolting), ISO 7042 or EN 14399-4 (HV nut) is specified. Nut proof load must exceed bolt proof load to prevent thread stripping.

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