Alloy Steel Grade 8.8 Bolts are tough, high-strength fasteners crafted for the most demanding mechanical, construction, and industrial tasks. Made from a carefully balanced alloy steel that includes just the right amount of carbon and other elements, these bolts deliver outstanding tensile strength, hardness, and impressive resistance to wear and deformation. With precise threading and smooth finishes, they ensure secure fastening, reliable load transfer, and long-lasting performance. You’ll find Alloy Steel Gr 8.8 Bolts in machinery, automotive applications, structural frameworks, and heavy engineering projects where safety, durability, and mechanical reliability are non-negotiable.
Alloy Steel Gr 8.8 Bolts are high-strength bolts produced from a mixture of carbon, manganese, phosphorus, sulfur, silicon, and boron. These bolts generally consist of 0.25-0.55% carbon, 0.30-1.60% manganese, 0.035% phosphorus (max), 0.035% sulfur (max), and 0.10-0.30% silicon, providing superior tensile strength and durability. With an 800 MPa minimum tensile strength and 640 MPa yield strength, they are best suited for heavy-duty applications demanding maximum load-bearing capacity and wear resistance, and thus they are a popular choice in structural and mechanical applications.
| AStm Standards | DIN ISO EN 4017 & 4014 DIN 933 / 931 & IS 1363 / 1363 |
| Size | Diameter 20 to 100 Milimeter / Inch 3/4 to 3.1/2 |
| Surface Finish | Zinc plated / Plain / Hot dip galvanised |
| CLASS | MATERIAL AND TREATMENT | C | C | P | S | B | TEMPERING TEMP. [C] |
|---|---|---|---|---|---|---|---|
| MIN | MAX | MAX | MAX | MAX | |||
| 8.8 | CARBON STEEL WITH ADDITIVES (E.G. B, MN OR CR) QUENCHED AND TEMPERED | 0.15 (D) | 0.4 | 0.025 | 0.025 | 0.003 | 425 |
| CARBON STEEL QUENCHED AND TEMPERED | 0.25 | 0.55 | 0.035 | 0.025 |
| Grades | Size Range | PS [MPa] | YS (min) [MPa] | TS (min) [MPa] | Hardness [Rockwell] |
|---|---|---|---|---|---|
| Class 8.8 | Under M16 | 580 | 640 | 800 | |
| 17-72 | 600 | 660 | 830 | C23–34 |
| Bolt Dia | Body Dia | Head Dia(F) | Head Height (H) | Degree of Slope | |||
|---|---|---|---|---|---|---|---|
| (D) | Max | Max Edge Sharp | Min Edge Sharp | Absolute Min Rounded | Max | Min | |
| 1/2 | 0.515 | 0.935 | 0.905 | 0.845 | 0.269 | 0.233 | 78° to 82° |
| 5/8 | 0.642 | 1.169 | 1.132 | 1.066 | 0.336 | 0.292 | 78° to 82° |
| 3/4 | 0.768 | 1.402 | 1.357 | 1.285 | 0.403 | 0.349 | 78° to 82° |
| 7/8 | 0.895 | 1.637 | 1.584 | 1.511 | 0.47 | 0.408 | 78° to 82° |
| 1 | 1.022 | 1.869 | 1.81 | 1.735 | 0.537 | 0.466 | 78° to 82° |
| 1-1/8 | 1.149 | 2.104 | 2.037 | 1.962 | 0.604 | 0.525 | 78° to 82° |
| 1-1/4 | 1.277 | 2.337 | 2.262 | 2.187 | 0.671 | 0.582 | 78° to 82° |
| 1-3/8 | 1.404 | 2.571 | 2.489 | 2.414 | 0.738 | 0.641 | 78° to 82° |
| 1-1/2 | 1.531 | 2.804 | 2.715 | 2.64 | 0.805 | 0.698 | 78° to 82° |
| Dimensions per ASME B18.5 1990 (R 1998) | |||||||
| Diameter Chart | M4 | M5 | M6 | M8 | M10 | M12 | M14 | M16 | M18 | M20 | M22 | M24 | M27 | M30 | M33 | M36 | M39 | M42 | M45 | M48 | M52 |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Pitch List | 0.7 | 0.8 | 1 | 1.25 | 1.5 | 1.75 | 2 | 2.5 | 3 | 3.5 | 4 | 4.5 | 5 | ||||||||
| GR A Length | 40 | 50 | 60 | 80 | 100 | 120 | 140 | 150 | Grade A not applicable to these dia’s | ||||||||||||
Head Across Flat (S) Nom = Max Min GR A GR B | 7 | 8 | 10 | 13 | 16 | 18 | 21 | 24 | 27 | 30 | 34 | 36 | 41 | 46 | 50 | 55 | 60 | 65 | 70 | 75 | 80 |
| 6.78 | 7.78 | 9.78 | 12.73 | 15.73 | 17.73 | 20.67 | 23.67 | 26.67 | 29.67 | 33.38 | 35.38 | GR A not applicable to these diameters | |||||||||
| 6.64 | 7.64 | 9.64 | 12.57 | 15.57 | 17.57 | 20.16 | 23.16 | 26.16 | 29.16 | 33 | 35 | 40 | 45 | 49 | 53.8 | 58.8 | 63.1 | 68.1 | 73.1 | 78.1 | |
Head Height Nom Tol + or – GR A GR B | 2.8 | 3.5 | 4 | 5.3 | 6.4 | 7.5 | 8.8 | 10 | 11.5 | 12.5 | 14 | 15 | 17 | 18.7 | 21 | 22.5 | 25 | 26 | 28 | 30 | 33 |
| 0.125 | 0.15 | 0.18 | 0.215 | GR A not applicable to these diameters | |||||||||||||||||
| 0.2 | 0.24 | 0.29 | 0.35 | 0.42 | 0.5 | ||||||||||||||||
Across corners e Min GR A GR B | 7.66 | 8.79 | 11.05 | 14.38 | 17.77 | 20.03 | 23.36 | 26.75 | 30.14 | 33.53 | 37.72 | 39.98 | GR A not applicable to these diameters | ||||||||
| 7.5 | 8.63 | 10.89 | 14.2 | 17.59 | 19.85 | 22.78 | 26.17 | 29.56 | 32.95 | 37.29 | 39.55 | 45.2 | 50.85 | 55.37 | 60.79 | 66.44 | 71.3 | 76.95 | 82.6 | 88.25 | |
Thread Length (b) For lengths < or = 125ilimeter For lengths > 12ilimeter <= 200milimeter For lengths > 200ilimeter | 14 | 16 | 18 | 22 | 26 | 30 | 34 | 38 | 42 | 46 | 50 | 54 | 60 | 66 | Not specified as full thread recommended | ||||||
| 20 | 22 | 24 | 28 | 32 | 36 | 40 | 44 | 48 | 52 | 56 | 60 | 66 | 72 | 78 | 84 | 90 | 96 | 102 | 108 | 116 | |
| 33 | 35 | 37 | 41 | 45 | 49 | 53 | 57 | 61 | 65 | 69 | 73 | 79 | 85 | 91 | 97 | 103 | 109 | 115 | 121 | 129 | |
| Major Diameter at thread (minimum) | 3.838 | 4.826 | 5.794 | 7.76 | 9.732 | 11.701 | 13.682 | 15.682 | 17.623 | 19.623 | 21.623 | 23.577 | 26.577 | 29.522 | 32.522 | 35.465 | 38.465 | 41.437 | 44.437 | 47.399 | 51.399 |
| Major Dia at thread (maximum) | 3.978 | 4.976 | 5.974 | 7.972 | 9.968 | 11.966 | 13.962 | 15.962 | 17.958 | ||||||||||||
We provide products that come with both mill test certificates and third-party test certificates, ensuring the highest standards of quality and compliance.
These bolts are primarily made of iron, combined with carbon, manganese, and a few trace elements like chromium or molybdenum to boost their mechanical properties. This unique blend guarantees high tensile and yield strength, toughness, and resistance to fatigue and shear forces. Mechanically speaking, they can handle significant static and dynamic loads, making them perfect for heavy-duty applications. Plus, heat treatment further enhances their hardness, wear resistance, and overall strength, ensuring they perform well even under tough conditions.
You’ll often see Alloy Steel Gr 8.8 Bolts in machinery assembly, automotive manufacturing, construction structures, industrial equipment, and structural supports. They’re perfect for securing metal, wood, and composite materials in situations that demand high-strength, reliable fastening. With their blend of durability, mechanical performance, and long-term reliability, Alloy Steel Gr 8.8 Bolts are the go-to choice for critical fastening needs in engineering and industrial projects.
Chetak Steel is a leading manufacturer, supplier and exporter of high-quality Carbon Steel, Alloy Steel, Mild Steel and Galvanized Steel products. Our extensive product range includes Pipes, Tubes, Flanges, Pipe Fittings, Forged Fittings, Sheets and Plates, catering to various industries in Hyderabad, India.
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