1. Chemical Composition
Table 1 – Chemical composition, unit: %
For all steel grades in this table, Cu shall not exceed 0.30%, Ni 0.20%, and Cr 0.20%.
2. Mechanical properties of wire rod
Table 2 Mechanical properties of wire rod resulting from Process D
| Grade | Wire diameter range mm | Tensile Strength N/mm² | Reduction of Area % | (Reference) Hardness HRB |
|---|---|---|---|---|
| SWCH19A SWCH16K SWCH17K SWCH18K SWCH20K | >3~4 | ≥640 | - | |
| >4~5 | ≥540 | |||
| >5~30 | ≥440 | ≤95 |
Notes: 1. For wire diameters exceeding 20 mm, the tolerance is the value in Table 2 minus 5. No tolerance is specified for diameters of 3 mm or less. 2. 1 N/mm² = 1 MPa
Table 3 Mechanical properties of wire rod resulting from the DA process
| Grade | Tensile Strength N/mm² | Reduction of Area % | (Reference) Hardness HRB |
|---|---|---|---|
| SWCH19A SWCH16K SWCH17K SWCH18K SWCH20K | ≥410 | ≤86 |
Notes: 1. For SWCH6R to SWCH27K grades, when the product is used as heat-treated wire, the lower limit of tensile strength may be set below the values in Table 3 upon agreement between supplier and purchaser. 2. For wire diameters exceeding 20 mm, the tolerance is the value in Table 3 minus 5. No tolerance is specified for diameters of 3 mm or less. 3. 1 N/mm² = 1 MPa
3. Depth of decarburized layer
Table 4 Permissible limits for average decarburized layer depth
| Unit: mm | ||
|---|---|---|
| Wire diameter | Ferrite decarburized layer depth | Total decarburized layer depth |
| ≤15 | ≤0.02 | ≤0.15 |
| >15~25 | ≤0.03 | ≤0.20 |
| >25~32 | ≤0.04 | ≤0.25 |
For SWCH30K to SWCH50K wire, when specified by the purchaser, the test in 10.3.1 shall be performed. The permissible limit for the average decarburized layer depth shall be in accordance with Table 4. However, for wire with a diameter exceeding 32 mm, the limits shall be agreed upon between the supplier and the purchaser.
4. Tolerance on wire diameter and out-of-roundness
Table 5 Tolerance on wire diameter and out-of-roundness
| Wire diameter | Permissible deviation | Out-of-roundness |
|---|---|---|
| ≤3 | 0-0.025 | ≤0.013 |
| >3 ≤6 | 0-0.030 | ≤0.015 |
| >6 ≤10 | 0-0.036 | ≤0.018 |
| >10 ≤18 | 0-0.043 | ≤0.022 |
| >18 ≤30 | 0-0.070 | ≤0.035 |
| >30 ≤40 | 0-0.100 | ≤0.050 |
| >40 ≤50 | 0-0.150 | ≤0.070 |
Note (4): Diameter deviation refers to the difference between the maximum and minimum diameters measured on the same cross-section of the wire.