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JIS G3445 STKM 13B Machine Structural Tubes

Release Tme: 2024-01-08
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Grade and Designation
The grade and designation of the tube shall be as given as follows table.
The sub-classification letter symbols A, B, and C, are used to indicate the distinction of manufacturing the tube, cold working process, heat treatment, etc.

Grade Designation
Grade 13 A STKM 13A
B STKM 13B
C STKM 13C

Method of Manufacture:

The tubes of STKM 13B shall be manufactured by seamless process, electric resistance welding process, or butt-welding process.

STKM 13B tubes shall be manufactured or in cold-finished condition or subjected to appropriate heat treatment.

World standard Comparative with JIS G3445 STKM 13

NUBER GRADE NUBER GRADE NUBER GRADE NUBER GRADE
13 Grade 13A STKM 13A A512 MT 1025 13 STKM 13A
A513 MTX 1025
A519 MT 1025
Grade 13B STKM 13B 13 STKM 13B 980 CDS-4
Grade 13C STKM 13C 13 STKM 13C

STKM 13(A, B, C) Chemical Composition

Grade Designation Unit %
C Si Mn P S Nb or V
Grade 13 A STKM 13A 0.25 max. 0.35 max. 0.30~0.90 0.040 max. 0.040 max.
B STKM 13B
C STKM 13C

STKM 13(A, B, C) Mechanical Properties

Designation Tensile strength

MPa{ksi}

Yield point or proof

MPa{ksi}

Elongation % Flattening

Strength

Distance

between

flat

plates (H)

(D is

outside dia.

of

the tube)

Bending strength    
   
   
No. 4, No. 4, Bend angle Inside radius    
No. 11 No. 5 (D is outside dia. of the tube)    
No. 12 test pieces Transverse direction    
test pieces Longitudinal direction      
STKM13A 370{38} min. 215{22} min. 30 min. 25 min. 2/3 D 90 6 D    
STKM13B 440{45} min. 305{31} min. 20 min. 15 min. 3/4 D 90 6 D    
STKM13C 510{52} min. 380{39} min. 15 min. 10 min.    

Appearance

The STKM 13B tubes shall be practically straight. and the two ends shall be at right angles to the axis of the tube

The STKM 13B tubes shall be free from defects detrimental to practical use.

The surface finish of the STKM 13B tubes, when especially specified, shall be agreed upon by the purchaser and the manufacturer.

Tolerance On Outside Diameter

Division Tolerance on the outside diameter
No. 1 Under 50mm ±0.5mm
50mm or over ±1%
No. 2 Under 50mm ±0.25mm
50mm or over ±0.5%
No. 3 Under 25mm ±0.12mm
25mm or over to and excl. 40mm ±0.15mm
40mm or over to and excl. 50mm ±0.18mm
50mm or over to and excl. 60mm ±0.20mm
60mm or over to and excl. 70mm ±0.23mm
70mm or over to and excl. 80mm ±0.25mm
80mm or over to and excl. 90mm ±0.30mm
90mm or over to and excl.100mm ±0.40mm
100mm or over ±0.50%

Tolerance On Thickness

Division Tolerances on wall thickness
No. 1 Under 4mm
+0.6mm
-0.5mm
4mm or over
15%
-12.50%
No. 2 Under 3mm
±0.3mm
3mm or over
±10%

Standard: JIS G3445

Description Name: STKM 13A steel tubes, STKM 13B steel tubes, STKM 13C steel tubes, JIS G3445 STKM 13B Steel pipes.

Size: 4mm-340mm

W.T.: 1mm-50mm

Shape: Round

Production type: Cold drawn, Cold rolled, Hot rolled, or Electric resistance welding.

Length: Single random length/ Double random length or as customer's actual request max length is 10m

Grade: STKM 13A, STKM 13B, STKM 13C

STKM 13B steel tubes

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