| Bolt grade identification marks | Material designation (from BS 1506) | Alloy type | Mechanical properties at room temperature | Charpy V-notch (KCV) impact strength at sub-zero temperatures for L grade bolting (1) | Heat treatment (5) | Sensitization time for inter-crystalline corrosion test | Corresponding grades of nuts inch series (4) |
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|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Limiting rule section | Tensile strength Rm | Yield strength Re | 0.2% proof stress Rp0.2 | Elongation A (based on a gauge length of 5.65 √So) |
Hardness HB | ||||||||||||
| Metric series | Inch series | min. | max. | min. | min. | max. | Temperature | Mean of three values | Solution treatment (5) | Precipitation hardening | |||||||
| Austenitic stainless steel | mm | N/mm 2 | N/mm 2 | N/mm 2 | N/mm 2 | % | °C | J | °C | °C | min. | ||||||
| MB 8 ML8 | B8 L8 | 304S31 | 18Cr10Ni | 160 | 520 | -- | -- | 205 | 40 | -- | -- | −196 | 70 | 1000 to 1100 | -- | 15 | 8 L8 |
| MB 8H | B8H | 304S51 | 160 | 520 | -- | -- | 205 | 40 | -- | -- | -- | -- | 1000 to 1100 | -- | n/a (2) | 8H | |
| MB8LN ML8LN | B8LN L8LN | 304S61 | 18Cr10NiN | 160 | 550 | -- | -- | 270 | 35 | -- | -- | −196 | 50 | 1000 to 1100 | -- | 30 | 8LN L8LN |
| MB8N ML8N | B8N L8N | 304S71 | 160 | 550 | -- | -- | 270 | 35 | -- | -- | −196 | 50 | 1000 to 1100 | -- | 15 | 8N L8N | |
| MB8M ML8M | B8M L8M | 316S31 | 18Cr12Ni2Mo2.5Mo | 160 | 520 | -- | -- | 205 | 40 | -- | -- | −196 | 70 | 1000 to 1100 | -- | 15 | 8M1 L8M1 |
| MB8M1 ML8M1 | B8M1 L8M1 | 316S33 | 160 | 520 | -- | -- | 205 | 40 | -- | -- | −196 | 70 | 1000 to 1100 | -- | 15 | 8M1 L8M1 | |
| MB8MH | B8MH | 316S51 | 18Cr12Ni2Mo2.5Mo | 160 | 520 | -- | -- | 205 | 40 | -- | -- | -- | -- | 1000 to 1100 | -- | n/a (2) | 8MH |
| MB8M1H | B8M1H | 316S53 | 160 | 520 | -- | -- | 205 | 40 | -- | -- | -- | -- | 1000 to 1100 | -- | n/a (2) | 8M1N | |
| MB8MLN ML8MLN | B8MLN L8MLN | 316S61 | 18C2Ni2MoN25MoN | 160 | 580 | -- | -- | 280 | 35 | – | – | –196 | 50 | 100 0 to 1100 | – | 30 | 8MLN L8MLN |
| MB8ML1N ML8ML1N | B8ML1N L8ML1N | 316S63 | 160 | 580 | -- | -- | 280 | 35 | – | – | –196 | 50 | 1000 to 1100 | – | 30 | 8M1LN L8M1LN | |
| MB8M1N ML8MN | B8MN L8MN | 316S65 | 18Cr12Ni2MoN2.5MoN | 160 | 580 | -- | -- | 280 | 35 | -- | -- | –196 | 50 | 1000 to 1100 | –- | 15 | 8MN L8MN |
| MB8M1N ML8M1N | B8M1N L8M1N | 316S67 | 160 | 580 | -- | -- | 280 | 35 | – | – | –196 | 50 | 1000 to 1100 | – | 15 | 8M1N L8M1N | |
| MB8T ML8T | B8T L8T | 321S31 | 18Cr10NiTi | 160 | 520 | -- | -- | 205 | 35 | -- | -- | –196 | 60 | 1000 to 1100 | –- | 30 | 8T L8T |
| MB8TH | B8TH | 321S51-490 | 18Cr10NiTi | 160 | 490 | -- | -- | 155 | 35 | -- | -- | -- | -- | 1070 to 1140 | -- | 30 | 8TH |
| MB8TH1 | B8TH1 | 321S51-520 | 160 | 520 | -- | -- | 205 | 35 | -- | -- | -- | -- | 950 to 1070 | -- | 30 | 8TH1 | |
| MB8C ML8C | B8C L8C | 347S31 | 1.8Cr10NiNb | 160 | 520 | – | – | 205 | 30 | -- | -- | –196 | 60 | 1000 to 1100 | –- | 30 | 8C L8C |
| MB8CH | B8CH | 347S51 | 18Cr10NiNb | 160 | 520 | -- | -- | 205 | 30 | -- | -- | -- | -- | 1000 to 1100 | – | 15 | 8CH |
| Precipitation hardenable alloys | |||||||||||||||||
| MB17B ML17B | B17B L17B | 286S31 | 15Cr25NiMoVTiAlB | 200 | 900 | – | – | 590 | 12 | 248 | 341 | –196 | 20 | 970 to 990 | 710 to 760 | n/a (2) | 17B L17B |
| MB17BM ML17BM | B17BM L17BM | 286S31 | 15Cr25NiMoVTiAlB | 200 | 900 | –- | –- | 590 | 12 | 248 | 321 | –196 | 20 | water quench | 16h min. air | n/a (2) | 17BM L17BM(7) |
| MB80A ML80A | B80A L80A | BS3076-NA20 | Ni20Cr | 300 | 1000 | -- | -- | 620 | 20 | 285 | 360 | -196 | 20 | 1080 °C soak upto 8h, air cool or quench | 850 °C soak 24h, air cool 700 °C 16h quench | n/2(2) | 80A L80A |
| Bolts metric and inch series available in the cold or warm-worked condition(selected alloys) | |||||||||||||||||
| Steels to BS 1506 | |||||||||||||||||
| 304S31 | 316S31 | 316S33 | 321S31 | 347S31 | 19 | 860 | -- | -- | 695 | 12 | –- | 320 | -196 | 27 | All bars solution treated 1000°C to 1100°C before cold drawing. Properties may be obtained by warm working. | n/a (3) | 304 316 316 321 347 |
| MB 8X | MB 8MX | MB 8MIX | MB 8TX | MB 8CX | >19 to 25 | 790 | -- | -- | 555 | 15 | -– | 320 | -196 | 27 | S31 S31 S33 S31 S31 | ||
| ML 8X | ML 8MX | ML 8MIX | ML 8TX | ML 8CX | >25 to 32 | 730 | -- | -- | 450 | 20 | –- | 320 | -196 | 27 | 8X 8MX 8MIX 8TX 8CX | ||
| B 8X | B 8MX | B 8MIX | B 8TX | B 8CX | >32 to 38 | 690 | -- | -- | 345 | 28 | –- | 320 | -196 | 27 | (6) | L8X L8MX L8MIX L8TX L8CX | |
| L 8X | L 8MX | L 8MIX | L 8TX | L 8CX | >38 to 44 | 650 | -- | -- | 310 | 28 | –- | 320 | -196 | 27 | |||
|
(1)
Charpy impact tests for L-grade bolts, only where specified on enquiry and order. |
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