ST52 seamless steel pipe

ST52 seamless steel pipe is a hollow, joint-free strip of steel extensively utilized for fluid transportation, including oil, natural gas, gas, water, and certain solid materials.

Applications of ST52 Seamless Steel Pipe

Compared to solid steel like round steel, ST52 seamless steel pipe offers a lighter weight while maintaining equivalent bending and torsional strength. This makes it an economical section steel, widely employed in manufacturing structural and mechanical parts such as:

- Oil drill pipes

- Automobile transmission shafts

- Bicycle frames

- Steel scaffolding used in construction

Using steel pipes to manufacture ring-shaped parts enhances material utilization, streamlines the manufacturing process, and saves on materials and labor. Examples include rolling bearing rings and jack sleeves, which are commonly produced using this method.

Mechanical Properties of ST52 Seamless Steel Pipe

- Yield Strength:

≤16mm:≥355 MPa

16-40mm:≥345 MPa

40-63mm:≥335 MPa

63-80mm:≥325 MPa

80-100mm:≥315 MPa

Above 100mm: As per agreement

- Tensile Strength:

490—630 MPa

- Elongation:

≥18%

- Impact Strength:

At 0℃:≥23 J

Production Process of Cold-Rolled ST52 Seamless Steel Pipe

The production of cold-rolled ST52 seamless steel pipe involves several steps:

Round tube blank

Heating

Piercing

Heading

Annealing

Pickling

Oiling

Multi-pass cold drawing

Blanking

Heat treatment

Straightening

Hydraulic testing

Marking

Storage

The cold-rolling process is more complex than hot-rolling, differing significantly from the fourth step onward. After the round tube blank is pierced, it undergoes heading and annealing. Post-annealing, the tube is pickled with a special acid, oiled, and subjected to multiple cold drawing passes followed by re-blanking and special heat treatment. After straightening, the steel pipe undergoes internal flaw detection using a metal flaw detector to identify cracks or bubbles. Post-quality inspection, the ST52 steel pipe is manually selected, marked with serial numbers, specifications, and production batch numbers, and finally stored using cranes.