ASTM A307 – Mechanical & Material Properties
The ASTM A307 specification establishes the chemical and mechanical requirements for carbon steel bolts, studs, and threaded rods. Commonly utilized in general engineering and structural applications, these fasteners are primarily categorized into Grade A (for general purpose use) and Grade B (specifically intended for flanged joints in piping systems). The following technical data provides a comprehensive breakdown of the tensile strength requirements relative to stress area, hardness ranges based on nominal length, and chemical analysis limits. These parameters are essential for ensuring material compliance and structural integrity in low-carbon steel fastening systems.
Mechanical Properties
This section details the minimum and maximum tensile requirements for Grade A and Grade B fasteners. Tensile strength is calculated based on the thread size and stress area, while hardness values (Brinell and Rockwell B) are specified to ensure the material meets the necessary ductility and strength thresholds.
| Tensile Requirements For Bolts, Studs, and Threaded Rods | |||||
|---|---|---|---|---|---|
| Thread Size, in. | Threads per inch | Stress Area, in.² | Tensile Strength, lbf | ||
| Grade A, min | Grade B | ||||
| min | max | ||||
| 1/4 | 20 | 0.0318 | 1 900 | 1 900 | 3 180 |
| 5/16 | 18 | 0.0524 | 3 100 | 3 100 | 5 240 |
| 3/8 | 16 | 0.0775 | 4 650 | 4 650 | 7 750 |
| 7/16 | 14 | 0.1063 | 6 350 | 6 350 | 10 630 |
| 1/2 | 13 | 0.1419 | 8 500 | 8 500 | 14 190 |
| 9/16 | 12 | 0.182 | 11 000 | 11 000 | 18 200 |
| 5/8 | 11 | 0.226 | 13 550 | 13 550 | 22 600 |
| 3/4 | 10 | 0.334 | 20 050 | 20 050 | 33 400 |
| 7/8 | 9 | 0.462 | 27 700 | 27 700 | 46 200 |
| 1 | 8 | 0.606 | 36 350 | 36 350 | 60 600 |
| 1 1/8 | 7 | 0.763 | 45 800 | 45 800 | 76 300 |
| 1 1/4 | 7 | 0.969 | 58 150 | 58 150 | 96 900 |
| 1 3/8 | 6 | 1.155 | 69 300 | 69 300 | 115 500 |
| 1 1/2 | 6 | 1.405 | 84 300 | 84 300 | 140 500 |
| 1 3/4 | 5 | 1.90 | 114 000 | 114 000 | 190 000 |
| 2 | 4 1/2 | 2.50 | 150 000 | 150 000 | 250 000 |
| 2 1/4 | 4 1/2 | 3.25 | 195 000 | 195 000 | 325 000 |
| 2 1/2 | 4 | 4.00 | 240 000 | 240 000 | 400 000 |
| 2 3/4 | 4 | 4.93 | 295 800 | 295 800 | 493 000 |
| 3 | 4 | 5.97 | 358 200 | 358 200 | 597 000 |
| 3 1/4 | 4 | 7.10 | 426 000 | 426 000 | 710 000 |
| 3 1/2 | 4 | 8.33 | 499 800 | 499 800 | 833 000 |
| 3 3/4 | 4 | 9.66 | 579 600 | 579 600 | 966 000 |
| 4 | 4 | 11.08 | 664 800 | 664 800 | 1 108 000 |
| Grade | Nominal Length, in. | Hardness | |||
|---|---|---|---|---|---|
| Brinell | Rockwell B | ||||
| min | max | min | max | ||
| A | Less than 3 × dia | 121 | 241 | 69 | 100 |
| 3 × dia and longer | ... | 241 | ... | 100 | |
| B | Less than 3 × dia | 121 | 212 | 69 | 95 |
| 3 × dia and longer | ... | 212 | ... | 95 | |
Material Properties
The chemical composition of ASTM A307 fasteners is strictly regulated to maintain weldability and performance. This table outlines the heat and product analysis limits for Carbon, Manganese, Phosphorus, and Sulfur, with specific sulfur variations between Grade A and Grade B to suit their respective applications.
| Element | Heat Analysis | Product Analysis |
|---|---|---|
| Carbon, max | 0.29 | 0.33 |
| Manganese, max | 1.20 | 1.25 |
| Phosphorus, max | 0.04 | 0.041 |
| Sulfur, max | ||
| Grade A | 0.15 | A |
| Grade B | 0.05 | 0.051 |