The specified content of any element specified in the steel for seamless steel pipes conforms to the limit value range of the corresponding elements listed in non-steel, square pipe and steel, and these steels are called non-steel.

What is seamless steel pipe non-steel

(ordinary carbon structure square pipe, high-quality carbon structure square pipe, carbon tool steel, carbon spring steel, free cutting carbon structural steel), pure iron (pure iron for electrical purposes, raw material pure iron) and other special non-steel with special properties.

Low steel usually includes weldable low and high strength structural steel, low reinforcement steel, low weathering steel and railway, mine and other special low steel.

Steel pipes usually include structural steel, spring steel, tool steel, high-speed tool steel, stainless steel, heat-resistant steel, bearing steel, non-magnetic steel, electrical silicon steel and so on. Usually the total element content of more than 10% of the steel pipe is called high steel pipe, common high steel pipe stainless steel, heat-resistant steel, high-speed tool steel, chromium stainless bearing steel, non-magnetic steel and so on.

What are the conditions for ordinary welded steel pipe non-steel pipe applications?

① The limit value of element content meets the requirements of GB/T 13304 for non-steel pipes.

(2) Heat treatment is not specified, but annealing, normalizing, stress relief and softening treatment are not treated as heat treatment.

(3) If the product standard or technical conditions are specified, its characteristic value should meet the following conditions:

Maximum carbon content ≥0.10%

The highest content of sulfur and phosphorus ≥0.045%

The highest nitrogen content was ≥0.007%

Minimum tensile strength ≤690Mφa

Minimum yield point or yield strength ≤360Mφa

Minimum elongation (L.=5.65√F). < 33%

Minimum bending core diameter ≥0.5x specimen thickness

Minimum impact power (20℃, V-shaped, longitudinal standard sample) ≤27J

Maximum Rockwell hardness (HRB) ≥60

The above specified values of mechanical properties refer to the properties of longitudinal or transverse specimens made of steel material with a thickness of 3 to 16mm.

④ No other quality requirements are specified.