The Chemical Composition of STKM11, STKM12, STKM13 and STKM14 are as the table below:
| Grade | Chemical Composition % | |||||
| C | Si | Mn | P | S | Nb or V | |
| STKM11A | ≤0.12 | ≤0.35 | ≤0.60 | ≤0.040 | ≤0.040 | ▾ |
| STKM12A | ≤0.20 | ≤0.35 | ≤0.60 | ≤0.040 | ≤0.040 | - |
| STKM12B | ||||||
| STKM12C | ||||||
| STKM13A | ≤0.25 | ≤0.35 | 0.30~ 0.90 |
≤0.040 | ≤0.040 | - |
| STKM13B | ||||||
| STKM13C | ||||||
| STKM14A | ≤0.30 | ≤0.35 | 0.30~ 1.00 |
≤0.040 | ≤0.040 | - |
| STKM14B | ||||||
| STKM14C | ||||||
The Mechanical Properties of STKM11, STKM12, STKM13 and STKM14 are as the table below:
| Grade | Mechanical Properties | Flattening Test | Bending Test | |||
| Tensile Strength (MPa) |
Yield Strength (MPa) |
Elongation (%) | Distance between that parts (D=OD) |
Bend Angle |
Inside Radius (D=OD) |
|
| No.11: Specimen | ||||||
| STKM11A | 230 (294) |
- | 235 | 1/2D | 180° | 4D |
| STKM12A | 235 (343) |
218 (177) |
235 | 2/3D | 90° | 6D |
| STKM12B | 240 (392) |
228 (275) |
225 | 2/3D | 90° | 6D |
| STKM12C | 248 (471) |
236 (353) |
220 | - | - | - |
| STKM13A; | 238 (373) |
222 (216) |
230 | 2/3D | 90° | 6D |
| STKM13B | 245 (441) |
231 (304) |
220 | 3/4D | 90° | 6D |
| STKM13C | 252 (510) |
239 (382) |
215 | - | - | - |
| STKM14A | 242 (412) |
225 (245) |
225 | 3/4D | 90° | 6D |
| STKM14B | 251 (500) |
236 (353) |
215 | 7/8D | 90° | 8D |
| STKM14C | 256 (549) |
242 (412) |
215 | - | - | - |
