U12, U12A, У12A, У12, C120U, 1.1555 - carbon tool steel
Table of content:
| Standard | Grade | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chemical composition % | |||||||||||||||
| C: | Si: | Mn: | P: | S: | Cr: | Ni: | Cu: | ||||||||
| GOST | У12 - U12 | ||||||||||||||
| 1.10-1.29 | 0.17-0.33 | 0.17-0.33 | <0.030 | <0.028 | <0.2 | <0.25 | <0.25 | ||||||||
| GOST | У12A - U12A | ||||||||||||||
| 1.10-1.29 | 0.17-0.33 | 0.17-0.28 | <0.025 | <0.018 | <0.2 | <0.12 | <0.2 | ||||||||
| PN | N12E | ||||||||||||||
| 1.15-1.24 | 0.15-0.30 | 0.15-0.30 | <0.025 | <0.025 | <0.15 | <0.2 | <0.2 | ||||||||
| PN | N12 | ||||||||||||||
| 1.15-1.24 | 0.15-0.35 | 0.15-0.35 | <0.030 | <0.030 | <0.2 | <0.25 | <0.25 | ||||||||
| GB | T12A - T00123 | ||||||||||||||
| 1.15-1.24 | <0.35 | <0.4 | <0.030 | <0.020 | <0.25 | <0.2 | <0.3 | ||||||||
| ISO | C120U - 1.1555 | ||||||||||||||
| 1.15-1.25 | 0.1-0.3 | 0.1-0.4 | <0.030 | <0.030 | - | - | - | ||||||||
| NF | C120E3U | ||||||||||||||
| 1.10-1.29 | 0.1-0.3 | 0.1-0.4 | <0.030 | <0.030 | - | - | - | ||||||||
| BS | BW1C | ||||||||||||||
| 1.11-1.3 | 0.1-0.3 | 0.1-0.35 | <0.15 | - | - | <0.2 | - | ||||||||
| MSZ | S121 / S122 | ||||||||||||||
| 1.15 – 1.24 | 0.15-0.35 | 0.15-0.35 | <0.025 | <0.025 | <0.2 | <0.25 | <0.25 | ||||||||
| UNI | C120KU | ||||||||||||||
| 1.10 – 1.29 | <0.3 | <0.35 | - | - | - | - | - | ||||||||
| JIS | SK120 | ||||||||||||||
| 1.15-1.24 | <0.35 | <0.5 | <0.030 | <0.030 | <0.3 | <0.25 | <0.25 | ||||||||
| UNE | C120 / F-1523 | ||||||||||||||
| 1.10-1.29 | <0.35 | <0.35 | <0.030 | <0.030 | <0.3 | - | - | ||||||||
U12A and U12 steels – description
High-carbon tool steel. Tools made of it are able to cut, grind and hit, due to ductility, grinding resistance, impact resistance and hardness.
Main features:
- Hard
- Good grinding resistance
- High cutting ability
- Ductile
- Good impact resistance
Applications
This alloy is widely used for:
- Files
- Die nuts
- Screw taps
- Die nuts
- Watchmaker tools
- Engraving tools
- Mason tools
- Stamps
- Knives
Mechanical properties
Hardness is one of the most important features of this steel.
| Norm | Grade | Max HB hardness as soft annealed | Max HB hardness as quenched |
|---|---|---|---|
| ISO | C120U | 217 | - |
| SEW | 43992 | 212 | 63 |
| GOST | U12 | 207 | 62 |
| GOST | U12A | 207 | 62 |
| SEW | 43991 | 212 | 63 |
| BS | BW1C | 207 | - |
| ČSN | 19221 | 210 | 64 |
| JIS | SK2 | 212 | - |
| PN | N12 | 207 | 63 |
| PN | N12E | 207 | 63 |
Other properties:
| Grade: | N12 | N12E | U12A |
|---|---|---|---|
| Electrical resistivity: | 1.96 μΩ*m | 1.96 μΩ*m | - |
| Density: | 7.830g/cm3 | 7.830g/cm3 | 7.79g/cm3 |
| Specific heat capacity: | 485 J/kg*K | 485 J/kg*K | - |
| Linear expansion coefficient: | 10.30 (10^6)/OC | 10.30 (10^6)/OC | - |
Quenching
U12 differs from U12A in it’s hardenability. U12 is a deep hardening steel and U12A is a shallow hardening one.
| Largest grain size / hardening depth, mm | Temperature [℃] | ||||||
|---|---|---|---|---|---|---|---|
| 760 | 800 | 840 | 880 | ||||
| Deep hardening steel N12 | 7 / 5 | 7 / 6 | 6 / 8 | 5 / 12* | |||
| Shallow-hardening steel N12E | 7 / 3 | 7 / 4 | 7 / 4 | 7 / 5 | |||
* ATTENTION! Hardening cracks on a fracture might be present.
Let's analyse the results. Quenching a N12 steel rod DN 20-25mm at 880℃ will result in throughly hardened fracture. In the case of N12E steel, an unhardened core app. DN10mm will remain inside the rod.
Heat treatment and Hot forming
Following parameters are recommended for working and heat treatment
| N12E heat treatment and forging | ||
|---|---|---|
| Process | Cooling | Temperature [℃] |
| Forging | sand or ash | 1000–800℃ |
| Soft annealing | any | 680–710℃ |
| Stress relief | slow | 600-700℃ |
| Quenching | fresh or salt water | 760-780℃ |
| Tempering | air | 180-300℃ |
Why the tempering range of temperatures so large? It's because it has a significant impact on the final tool hardness. Hence the tempering temperature should be selected within this limit.
Welding
Welding is hard and should be considered only as a mean to repair.
Following coated electrodes may be used: EN 450 B, ENS 50 B, ENS 15CrB, EN 350 B, ENS 18, EN 600 B, WBEN 280 MoB.
We deliver this steel alloy as:
Replacements, equivalents and other designations:
N12, N12E, T12A, T00123, U12, U12A, 19221, C120U, 1.1555, C120E3U, MOULURE TALABOT, BW1C, S121, S122, C120KU, SK120, C120, F-5123