Steel generally used in large size bolts up to 4” that require high performance of resilience at low temperatures , it has the same mechanical characteristics as the ASTM A320 L7 quality.
Standard Reference: ASTM A320/A320M
| EUROPE | ITALY | GERMANY | FRANCE | UK | USA | ||
|---|---|---|---|---|---|---|---|
| - | (UNI 7847 - 78) | (DIN) | (NF A 35-552-86) | (BS 970 pt. 1 - 96) | ASTM A 29 | ||
| Grade | N° | Werkstoff | N° | ||||
| (40NiCrMo7) | (1.6565) | (40NiCrMo7) | (40NiCrMo8-4) | (1.6562) | - | (817M40) | 4340 |
| C | Si | Mn | P/max | S/max | Cr | Mo | Ni | Al |
|---|---|---|---|---|---|---|---|---|
| 0,38 ÷ 0,43 | 0,15 ÷ 0,35 | 0,60÷0,85 | 0,035 | 0,040 | 0,70 ÷ 0,90 | 0,20 ÷ 0,30 | 1,65 ÷ 2,00 | 0,020 ÷ 0,050 |
| Size (mm) |
Quenched and tempered (+QT) |
|||||
|---|---|---|---|---|---|---|
| Rp0,2 (MPa) min |
Rm (MPa) min |
A5 (%) min |
Z (%) min |
HB max |
KV-101°C/ min |
|
| d≤100 | 725 | 860 | 16 | 50 | 321 | 27J |
| * Minimum tempering temperature 593°C. | ||||||
| Operation | °C |
|---|---|
| Hot forgings deformation | 900÷1100 |
| Isothermal annealing | 800÷900-->640 |
| Normalizing | 860÷880 |
| Quenching in water or oil | 830÷860 |
| Tempering | 550÷650 |
| Limits of range | Hardness HRC at a distance from quenched end of test pieces (mm) | ||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1,5 | 3 | 5 | 7 | 9 | 11 | 13 | 15 | 20 | 25 | 30 | 35 | 40 | 45 | 50 | |||||||
| +H | Max | 60 | 60 | 60 | 60 | 60 | 60 | 60 | 60 | 59 | 58 | 58 | 58 | 57 | 56 | 56 | |||||
| Min | 52 | 52 | 52 | 52 | 52 | 52 | 52 | 52 | 51 | 50 | 49 | 48 | 47 | 45 | 44 | ||||||
