Precision tubes for hydraulic systems, automobiles, machinery, and other precision steel pipe, finish, cleanliness, there are areas of high mechanical performance requirements.

STKM13A Seamless tubes 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

JIS 3445 STKM 13A and STKM 13B Mechanical Properties:

Standard	Steel Grade	Tensile Strength (MPa)	Yield Point (MPa)	Elongation(%)
JIS G3445	STKM13A	≥375	≥215	≥30
JIS G3445	STKM13B	≥440	≥305	≥20

Pipe Tolerance Table
Name	Rang(mm)	German Standard(mm)	Corporate Internal Control Standards(mm)	Special High-Precision(mm)
Outer Diameter	4-30	±0.08	±0.05	±0.03
	31-40	±0.15	±0.05	±0.03
	41-50	±0.20	±0.08	±0.03
	51-60	±0.25	±0.08	±0.03
Wall thickness	0.5-7	±10%	±10%, Min±0.05	±10%, Min±0.03
Length	+/-10mm	Automotive industry pipe length can be cut according to customer requirements.

Heat treatment process delivery conditions:
Delivery Condition	Heat Treatment Process
+C	Cold drawn / hard. After the final cold forming no heat treatment.
+LC	Cold drawn/soft. After the final heat treatment-limiting deformation, cold drawn, allowing a degree of cold deformation
+SR	Steel heat treatment is applied after the last cold deformation process, the result of state steel after due process, the residual stress deformation and machining makes a certain degree of difficulty increases.
+A	In the final step of the steel pipe after cold deformation, placed in a controlled atmosphere furnace for annealing.
+N	In the final step of the steel pipe after cold deformation, placed in a controlled atmosphere furnace at a temperature above the phase transition point to continue annealing.