China · GB
28SiMnB
GB/T 1222:2016 — Spring steels
Chemical composition
| Element | min | max | Similar | Remarks |
|---|---|---|---|---|
| B | 0.0008 | 0.0035 | ||
| C | 0.24 | 0.32 | ||
| Cr | 0.25 | |||
| Cu | 0.25 | |||
| Mn | 1.2 | 1.6 | ||
| Ni | 0.35 | |||
| P | 0.025 | |||
| S | 0.02 | |||
| Si | 0.6 | 1 |
Mechanical properties
| Heat treatment / condition | Yield strength | Tensile strength | Elongation | Reduction of area | Impact energy | Hardness |
|---|---|---|---|---|---|---|
| quenched and tempered | ≥1180 | ≥1275 | ≥5 | ≥25 | ||
| hot rolled | HB ≤302 |
Heat treatment
| Type | 3 | 4 |
|---|---|---|
| Heat-treatment process | 淬火+回火 | 淬火温度900℃，淬火介质水、油，回火温度320℃。 |