SNCM431 4340 DIN 1.6580 30CrNiMo8 Hardened Steel
4340 SNCM431 DIN1.6580 30CrNiMo8 Hardened Steel
1. 4340 Applications
Alloyed heat treatable steel with a typical tensile strength of 1100 -1300 N/mm². Used for highly stressed components, where the combination of high strength with tenaciousness is of utmost importance. High cold formability: Parts of different shape can be manufactured, a favorable fibering for stress, a very good surface condition and an high dimensional accuracy. When cold formed the smooth surface leads to an increased fatigue and vibratory strength.
2.All Grades Comparison
| Material no. |
DIN |
BS |
ASTM |
| 1.6580 |
30CrNiMo8 |
823M30 |
4340 |
| AFNOR |
ISO |
ГOCT |
JIS |
| 30CND8 |
31CrNiMo8 |
3KH3M3F |
SNCM431 |
3. 4340 Chemical Composition(%)
| Steel Grade |
C |
Mn |
Si |
P |
S |
Cr |
Ni |
Mo |
| 30CrNiMo8 |
0.26-0.34 |
0.50-0.80 |
0.40 max |
0.025 max |
0.035 max |
1.80-2.20 |
1.80-2.20 |
0.30-0.50 |
| 4340 |
0.38–0.43 |
0.60-0.80 |
0.15-0.35 |
0.035 max |
0.040 max |
0.70-0.90 |
1.65-2.00 |
0.20-0.30 |
| SNCM431 |
0.27-0.35 |
0.60-0.90 |
0.15-0.35 |
0.030 max |
0.030 max |
0.60-1.10 |
1.60-2.00 |
0.15-0.30 |
4. 4340 Mechanical Properties(T=20°C if not differently stated)
| Heat treatment state |
Diameter(mm) |
Rm (Mpa) |
Rp0.2 (Mpa) |
Fracture elongation A5 (%) |
Notch impact energy ISO-V [J] |
Hardness (HB) |
| SOFT ANNEALED |
/ |
844 min |
/ |
/ |
/ |
250 max |
| ISOTHERMAL ANNEALED |
/ |
615-815 |
/ |
/ |
/ |
183-242 |
| QUENCHED AND TEMPERED |
16 max |
880-1080 |
685 min |
16 min |
40 min |
289-347 |
| QUENCHED AND TEMPERED |
16-40 |
930-1080 |
735 min |
16 min |
40 min |
275-318 |
| QUENCHED AND TEMPERED |
40-100 |
880-1030 |
685 min |
17 min |
40 min |
261-303 |
| QUENCHED AND TEMPERED |
100-250 |
785-935 |
635 min |
18 min |
35 min |
233-276 |
| QUENCHED AND TEMPERED |
250-500 |
735-885 |
590 min |
16 min |
35 min |
218-262 |
5.HEAT TREATMENT AND HOT PLASTIC DEFORMATION TEMPERATURES
| – |
TEMPERATURE ° C |
Cooling Medium |
| Hot plastic deformation |
850-1100 |
/ |
| Normalizing |
850-880 |
air |
| Soft Annealing |
650-690 |
air |
| Quenching |
830-860 |
oil |
| Tempering |
540-660 |
air |
