1.7220 | 34CrMo4 +Q
| Numeric designation | 1.7220 |
|---|---|
| Chemical designation | 34CrMo4 |
| State | +Q (only hardened, not tempered) |
| Etching | 3% Nital |
This chromium and boron-alloyed screw material 34CrMo4 is available in the following heat treatment conditions and strength classes:
- [557 HV 1] hardened, not tempered (tetragonal martensite)
- 407 HV 1] Strength class 12.9 (lowest tempering temperature)
1st number x 100 = Rm
1st x 2nd number x 10 = Rp0.2.
In the purely hardened state, the microstructure consists of tetragonal martensite. You can see a nice comparison of the needle structure if you compare the tetragonal martensite with the strength class 12.9.
The strength class is set via the height of the tempering temperature. The higher this is, the lower the strength values. No epsilon carbides can be seen in the images at 1000x optical magnification.
