A320 L7 - A320 L7M
Steel produced at the quenched and tempered state according to the United States standard ASTM A320, used for linkages and bolts destined for use at low temperature in the oil industry. It has mechanical characteristics similar to the A193 B7 type, but additionally guarantees resilience values at low temperature. The B7M version, produced at higher temperatures, has slightly lower resistance characteristics but greater plasticity.
References and Comparable Standards
Standard Reference: ASTM A 320
| EUROPE |
ITALY |
GERMANY |
FRANCE |
UK |
USA |
| EN 10083-3: 2006 |
(UNI 7845-78) |
(DIN 17200 - 86) |
(NF A 35-552-86) |
(BS 970 pt. 1 - 96) |
ASTM A 320 |
| Grade |
N° |
|
Werkstoff |
N° |
|
|
|
| 42CrMo4 |
1.7225 |
42CrMo4 |
42CrMo4 |
1.7225 |
42CD4 |
708M40 |
L7 |
L7M |
| 4140 |
4142 |
Chemical Composition (Cast Analysis) (%)
| C |
Si |
Mn |
P/max |
S/max |
Cr |
Mo |
Al |
| 0,38 ÷ 0,48 |
0,15 ÷ 0,35 |
0,75÷1,00 |
0,035 |
0,040 |
0,80 ÷ 1,10 |
0,15 ÷ 0,25 |
0,020÷0,050 |
Mechanical Properties - Quenched
| |
Size (mm) |
Rp 0,2 (MPa) min |
Rm (MPa) min |
A4 (%) min |
Z (%) min |
KV (J) min |
Hardness max |
| A320L7 |
d≤65 |
725 |
860 |
16 |
50 |
27 (-101°C) |
321 HB or 35 HRC |
| L7M* |
d ≤65 |
550 |
690 |
18 |
50 |
27 (-73°C) |
235 HB or 99 HRB |
* minimum tempering temperature 620°C
Working Temperatures Recommended
| Operation |
°C |
| Hot forgings deformation |
850÷1150 |
| Normalizing |
850÷880 |
| Soft annealing |
680÷720 |
| Quenching in oil or water |
830÷850 |
| Tempering |
620÷650 |
