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This handbook provides a consolidated reference of the three major ASTM standards for industrial bolting: ASTM A193 (high■temperature bolts), ASTM A194 (nuts), and ASTM A320 (low■temperature bolts). It includes material types, chemical requirements, mechanical properties, and key application notes.
| Grade | Material Type | Typical Chemistry | Mechanical Properties |
|---|---|---|---|
| B7 | Alloy Steel (4140/4142) | Cr-Mo; Quenched & Tempered | TS ≥ 860 MPa, YS ≥ 720 MPa, Hardness 248–341 HB |
| B7M | Alloy Steel (Lower Strength) | Similar to B7 with controlled hardness | TS ≥ 620 MPa, improved corrosion cracking resistance |
| B16 | Cr-Mo-V Alloy Steel | Cr-Mo-V high temperature alloy | TS ≥ 895 MPa, high temp usage |
| B8 | Stainless Steel 304 | 18Cr–8Ni Austenitic | Class 1 Annealed; Class 2 Strain Hardened |
| B8M | Stainless Steel 316 | 18Cr–12Ni–2.5Mo | Class 1 Annealed; Class 2 Strain Hardened |
| B8T | Stainless Steel 321 | Ti stabilized | High temp resistance |
| B8C | Stainless Steel 347 | Cb stabilized | Improved creep resistance |
| Grade | Material Type | Typical Chemistry | Mechanical Properties |
|---|---|---|---|
| 2H | Carbon / Alloy Steel | Quenched & Tempered | Proof Load: 175 ksi, Hardness 223–302 HB |
| 2HM | Carbon Steel (Low Hardness) | Modified chemistry | Lower hardness to prevent H₂ embrittlement |
| 7 | Alloy Steel | Cr-Mo steel | Used with A193 B16 fasteners |
| 7M | Alloy Steel (Low Strength) | Similar to Gr.7 | Lower hardness version |
| 8 | Stainless Steel 304 | 18Cr–8Ni | Corrosion resistant |
| 8M | Stainless Steel 316 | 18Cr–12Ni–2.5Mo | Superior corrosion resistance |
| 8T | Stainless Steel 321 | Ti stabilized | High-temp resistance |
| 8C | Stainless Steel 347 | Cb stabilized | Improved creep/oxidation |
| Grade | Material Type | Typical Chemistry | Mechanical Properties |
|---|---|---|---|
| L7 | Alloy Steel (4140/4142) | Cr-Mo; Quenched & Tempered | TS $\ge$ 860 MPa; Impact tested at $-50^\circ\text{C}$ |
| L7M | Alloy Steel (Low Strength) | Modified hardness | Impact tested; lower hardness reduces cracking |
| L43 | Ni-Cr-Mo Steel | High strength low temp alloy | High impact toughness at $-100^\circ\text{C}$ |
| B8 | SS 304 | 18Cr–8Ni | Class 1 Annealed; Class 2 Strain Hardened |
| B8M | SS 316 | 18Cr–12Ni–2.5Mo | Superior corrosion and low-temp toughness |
| Grade | Material Type | Typical Chemistry | Mechanical Properties |
|---|---|---|---|
| Grade 2H | Carbon Steel / Alloy Steel | Quenched & Tempered; C-Mn alloy | Proof Load: 175 ksi; Hardness: 223–302 HB; Used with A193 B7 |
| Grade 2HM | Carbon Steel (Lower Hardness) | Modified 2H chemistry | Lower hardness to reduce H2 embrittlement risk |
| Grade 4 | Mo-Alloy Steel | Molybdenum alloyed steel | High-temperature applications |
| Grade 7 | Alloy Steel | Cr-Mo steel (annealed or tempered) | Used with A193 B16 |
| Grade 7M | Alloy Steel (Low Strength) | Similar to Grade 7 | Controlled hardness version |
| Grade 8 | Stainless Steel 304 | 18Cr–8Ni Austenitic SS | Corrosion resistant; non-magnetic |
| Grade 8M | Stainless Steel 316 | 18Cr–12Ni–2.5Mo | Superior corrosion resistance |
| Grade 8T | Stainless Steel 321 | Ti stabilized SS | Improved high-temperature resistance |
| Grade 8C | Stainless Steel 347 | Cb stabilized SS | Enhanced creep resistance |
| Grade | Material Type | Typical Chemistry | Mechanical Properties |
|---|---|---|---|
| A193 B7 | Alloy Steel (4140/4142) | Cr-Mo steel; Quenched & Tempered | TS: 860 MPa min; YS: 720 MPa min; Hardness: 248–341 HB |
| A193 B7M | Alloy Steel (Low Strength) | Similar to B7 with controlled hardness | TS: 690 MPa min; Lower hardness for corrosion resistance |
| A193 B16 | Alloy Steel (Cr-Mo-V) | High temp alloy with Vanadium | TS: 895 MPa min; Used in high-temperature service |
| A193 B8 | Stainless Steel 304 | 18Cr–8Ni Austenitic SS | Class 1: Annealed; Class 2: Strain Hardened; TS: ~515–860 MPa |
| A193 B8M | Stainless Steel 316 | 18Cr–12Ni–2.5Mo | Class 1: Annealed; Class 2: Strain Hardened; TS: ~515–860 MPa |
| A193 B8T | Stainless Steel 321 | Ti stabilized SS | Good high-temperature performance |
| A193 B8C | Stainless Steel 347 | Cb stabilized SS | Better creep resistance |
Disclaimer - Dimensional data and technical information for ASTM A193 + A194 + A320 was obtained from publicly available sources and not acquired through standards agencies. It has been completed and compiled for reference purposes only; where discrepancies are found they are subject to change without notice. Aim Tech makes no warranties or representations regarding the accuracy and validity of the compiled information and data. Contact the relevant standards authorities for accurate and detailed information.