1. Chemical Composition
Table 1 -- Chemical Composition, %
| Grade | C | Si | Mn | P | S | Cr | Mo | Ni | Cu a） |
|---|---|---|---|---|---|---|---|---|---|
| SUJ3 | 0.95~1.10 | 0.40~0.70 | 0.90~1.15 | ≤0.025 | ≤0.025 | 0.90~1.20 | ≤0.08 | ≤0.25 | ≤0.25 |
| Elements not specified in this table shall not be intentionally added except for the purpose of finishing the molten steel, unless agreed upon between the parties involved. Note a) The Cu content in wire rod shall be 0.20% or less. | |||||||||
Elements not specified in this table shall not be intentionally added except for steelmaking purposes; any such addition shall be determined by agreement between the supplier and the purchaser.
Note a) The Cu content in wire rod shall be 0.20% or less.
Note a) The Cu content in wire rod shall be 0.20% or less.
2. Mechanical properties of wire rod
Mechanical property values shall be determined by agreement between the supplier and the purchaser.
3. Dimensional Tolerances
4. Permissible Limits for Total Decarburized Layer Depth
Table 9 - Permissible Limits for Total Decarburized Layer Depth (Cold-Drawn Steel)
| Cold-Drawn Round Bar | Cold-Drawn Wire | ||
|---|---|---|---|
| Diameter | Total decarburized layer depth from the surface | Diameter | Total decarburized layer depth from the surface |
| <15 | <0.20 | ≤7 | <0.05 |
| 15<d≤25 | <0.25 | 7<d≤15 | <0.08 |
| 25<d≤35 | <0.30 | 15<d≤20 | <0.10 |
Permissible tolerances for cold-drawn round steel with diameters exceeding 35 mm and cold-drawn steel wire with diameters exceeding 20 mm shall be subject to agreement between the supplier and the purchaser.
5. Hardness
Table 10 – Spheroidizing annealing hardness (rolled steel for machining)
| Grade | Hardness | ||
|---|---|---|---|
| HBW | HRB | HV | |
| SUJ3,SUJ5 | <207 | <95 | <223 |
For hot-rolled steel for machining that has undergone spheroidizing annealing, testing is performed in accordance with Clause 14.3, and hardness is expressed as Brinell hardness (HBW), Rockwell hardness (HRBW), or Vickers hardness (HV) as specified in Table 10. However, Vickers hardness (HV) applies only to diameters of 17 mm or less. The hardness of cold-drawn steel and the low-temperature annealing hardness of steel for forging shall be subject to agreement between the supplier and the purchaser.