High-quality low-alloy seamless steel pipes mainly include the following types under the national standards:

① Weldable low-alloy high-strength structural steel, the specified yield strength is greater than 360Mφa, less than 420Mφa

② Boiler seamless steel pipe and pressure vessel pipe, such as GB713, GB6653, GB6654, GB6655 and other provisions.

③ For shipbuilding, as stipulated by GB712.

④ For automobile use, as stipulated by GB3273.

⑤ Bridges, such as YB169 and other provisions.

⑥ Bicycle, such as GB3646GB3647 provisions.

⑦ Low alloy weathering steel, such as GB4171, GB4172 provisions.

⑧ Railway, such as GB2585, GB8603, GB8604 and other specified rail steel, special-shaped steel.

⑨ For mining (except ordinary quality steel).

⑩ For oil and gas pipelines.

High-quality seamless pipe pipe mainly includes what steel?

① Seamless pipe for general engineering structure.

② Seamless steel, such as GB1499 regulations of 40Si2MnV and other seamless pipes.

(3) Electrical silicon (aluminum) steel (no permeability requirements), such as GB2521, GB5212 and other provisions of the production of silicon (aluminum) steel strip (sheet) steel.

④ For railway.

⑤ Seamless pipe for geological and oil drilling, such as seamless pipe for the production of geological and oil drilling steel pipe stipulated by YB235 and YB528.

⑥ Sulfur and phosphorus steel pipes are more than 0.035% wear-resistant steel and silicon manganese spring steel.

What conditions should special non-alloy tube steel meet?

(1) Steel to be heat treated and have at least one of the following special requirements of non-seamless pipe:

① The impact performance of quenching and tempering or simulated surface hardening is required;

The depth or surface hardness of the hardened layer required after quenching or quenching and tempering;

(3) The requirements for limiting surface defects are more stringent than those for cold heading and cold extrusion steel;

(4) Requirements for non-metallic inclusion steel pipes and (or) requirements for internal material uniformity.

(2) The steel is not heat treated and should have at least one of the following special requirements of the non-seamless pipe:

(1) It is required to limit the uniformity of non-metallic inclusion steel pipes and (or) internal materials, such as the laminar tear resistance of steel plates;

(2) The maximum value of phosphorus steel pipe and (into) sulfur steel pipe is required to be limited, and the melting analysis value should be less than 0.020%; The analytical value of the finished product should be ≤0.025%;

③ The following restrictions are required for the steel pipe with residual elements.

Cu smelting analysis of the highest steel pipe < 0.10%

Co smelting analysis maximum steel pipe ≤0.05%

V Melting analysis maximum content < 0.05%

The surface quality requirements are more stringent than those for cold tender and cold extrusion steel.

Steel with specified conductivity (not less than 9S/m) or with specified magnetic properties (except for magnetic sheets and strips that specify only the maximum magnetic loss and minimum magnetic induction intensity but not the permeability).