JIS 3445 steel pipes are suitable for machinery, automobiles, bicycles, furniture, appliances and other mechanical parts. The main grades are STKM11A, STKM12(A,B,C), STKM12(A,B,C), STKM(A,B,C).
The Chemical Composition of JIS 3445 STKM11, STKM12, STKM13 and STKM14 Mechanical Tubes 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 JIS 3445 STKM11, STKM12, STKM13 and STKM14 Carbon Steel Mechanical Tubing 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 | - | - | - |
Tolerances of JIS G3445 STKM12A/STKM12B Tube on Outside Diameter:
No 1: when outer diameter <50mm, tolerance 0.5mm;when outer diameter ≥50 mm,tolerance +/- 0.1mm;
No 2: when outer diameter <50mm, tolerance 0.25mm;when outer diameter ≥50 mm,tolerance +/- 0.5mm;
No 3: when outer diameter <25mm, tolerance 0.12mm;when 25mm ≤od ≥40 mm,tolerance +/- 0.15mm;
when 40mm ≤od ≥50 mm,tolerance +/- 0.18mm.
