DIN2391 Seamless Precision Steel Pipes

March 23, 2026

DIN2391 Seamless Precision Steel Pipes

DIN 2391 Seamless Precision Steel Tubes

DIN 2391 is a German standard for cold-drawn or cold-rolled seamless precision steel tubes, now superseded by EN 10305-1 (Steel tubes for precision applications – Part 1: Seamless cold drawn tubes). These tubes are characterized by tight dimensional tolerances, smooth surface finish, and consistent mechanical properties, making them ideal for high-precision applications in hydraulic/pneumatic systems, automotive components, and mechanical engineering.

Key Applications

Hydraulic and pneumatic cylinders/lines
Precision mechanical shafts and sleeves
Automotive chassis and fuel injection systems
Instrumentation and measuring equipment
High-pressure fluid transport lines

Chemical Composition (Typical Grades)

Below are the standard chemical composition limits for common DIN 2391 steel grades (mass fraction, %):

Element	St 35 (1.0308)	St 45 (1.0503)	St 52 (1.0832)
C	≤ 0.17	≤ 0.45	≤ 0.22
Si	≤ 0.35	≤ 0.35	≤ 0.55
Mn	≤ 0.80	≤ 0.80	≤ 1.60
P	≤ 0.045	≤ 0.045	≤ 0.045
S	≤ 0.045	≤ 0.045	≤ 0.045
Cr	≤ 0.30	≤ 0.30	≤ 0.30
Ni	≤ 0.30	≤ 0.30	≤ 0.30
Cu	≤ 0.30	≤ 0.30	≤ 0.30

Mechanical Properties (Tensile Strength & Yield Strength)

Mechanical properties vary by grade and delivery condition (heat treatment). Common conditions include:

BKS: Cold-drawn, stress-relieved
GBK: Annealed
NBK: Normalized

Tensile Strength & Yield Strength Table

Grade	Delivery Condition	Tensile Strength (Rm, MPa)	Yield Strength (ReH, MPa)	Elongation (A5, %)
St 35	BKS	340 – 470	≥ 235	≥ 25
St 35	GBK/NBK	315 – 440	≥ 235	≥ 25
St 45	BKS	420 – 560	≥ 340	≥ 14
St 45	GBK/NBK	380 – 520	≥ 315	≥ 16
St 52	BKS	480 – 620	≥ 420	≥ 10
St 52	GBK/NBK	440 – 580	≥ 390	≥ 12

Kontaktdaten

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DIN2391 Seamless Precision Steel Pipes