TT 8.8
The steel solution for cold forming operations. Despite an initial strength similar to that of DIN property class 8.8, TT 8.8 has excellent cold-working properties. There is therefore no need for heat treatment or other downstream procedures such as straightening and cleaning. TT 8.8 is the high-strength special steel solution for all applications that demand steel stock with excellent cold working, bending and welding properties. Choose TT 8.8 for lower costs and greater competitivenes.Product range
| Process | Size range (mm) | Tolerance |
|---|---|---|
| Drawn | ≥ 4.0 – ≤ 28.0 | h9 |
| Ground | ≥ 4.0 – ≤ 28.0 | ≥ IT6 |
Bar lengths: 3–6.5 m
Colour coding: yellow end-face
Chemical analysis
| Element | C | Si | Mn | P | S |
|---|---|---|---|---|---|
| min. | 0.24 | 0.10 | 1.20 | 0.02 | |
| max. | 0.29 | 0.30 | 1.50 | 0.04 | 0.04 |
Deviation of product analysis from limits specifi ed in cast analysis in accordance with EN 10087. Killed with aluminium or agents having a similar effect. The analysis complies with SAE 1527, comparable with 28Mn6 (1.1170).
Mechanical properties as drawn
| Static | |||||
|---|---|---|---|---|---|
| Dimensions | Ø | mm | ≤ 16 | >16 – 30 | >30 – 40 |
| Proof stress | Rp0.2 | N/mm2 | ≥ 660 | ≥ 660 | ≥ 660 |
| Tensile strength | Rm | N/mm2 | 800 – 950 | 830 – 950 | 800 – 950 |
| Ultimate elongation | A5 | % | ≥ 12 | ≥ 12 | ≥ 12 |
| Reduction of area | Z | % | ≥ 45 | ≥ 45 | ≥ 45 |
| Hardness | HV10 | 230 – 300 | 255 – 336 | 230 – 300 | |
| Notched impact energy | AURT (ISO-U) | J | ≥ 22 | ≥ 22 | ≥ 22 |
| Dynamic | |||||
|---|---|---|---|---|---|
| Tension/compression | σzdw | N/mm2 | ap. 360 | ||
| Reverse bending | |||||
| Specimen without notch | σbw | N/mm2 | ap. 390 | ||
| Specimen with notch ɑk=4.0 | σbw | N/mm2 | ap. 125 | ||
| Torsional reversal | Ʈtw | N/mm2 | ap. 175 |
