Process classification

Square pipe according to the production process: hot rolled seamless square pipe, cold drawn seamless square pipe, extrusion seamless square pipe, welded square pipe.

Welded square pipe is divided into:

(a) According to the process, it is divided into two parts: arc welded square pipe, resistance welded square pipe (high frequency and low frequency), gas welded square pipe and furnace welded square pipe

(b) It is divided into straight welded square pipe and spiral welded square pipe according to the weld

Material classification

The square pipe is divided into ordinary carbon steel square pipe and low alloy square pipe according to the material. Commonly used carbon steel is divided into Q195, Q215, Q235, SS400, 20 × steel, 45 # steel, etc. Low alloy steel is divided into Q345, 16Mn, Q390, St52-3 and so on.

Production standard classification

Square tube is divided into national standard square tube, Japanese standard square tube, British standard square tube, American standard square tube, European standard square tube and non-standard square tube.

Section shape classification

The square pipe is classified by section shape:

(1) Square tubes with simple cross sections - square tubes and rectangular square tubes

(2) Complex cross section square pipe - flower square pipe, open square pipe, corrugated square pipe, shaped square pipe

Classification of surface treatments

According to the surface treatment method, the square pipe is divided into hot-dip galvanized square pipe, electric galvanized square pipe, oil coated square pipe and pickling square pipe

Usage classification

Square tube classification uses square for decorative pipe, square tube machine tool equipment, square tube machinery industry, square tube for chemical industry, square steel structure pipe, square tube for shipbuilding, square tube for automobiles, steel beam column square tube, square tube special

Wall thickness classification

Square pipes are classified according to wall thickness - super thick square pipe, thick square pipe and thin wall square pipe

Square tube performance

Step 1: Plasticity

Plasticity refers to the ability of metal materials to produce plastic deformation under load without damage.

2. Hardness

Hardness is a measure of how soft and hard a metal material is. At present, the commonly used hardness measurement method in production is pressed hardness method. It is pressed into the metal surface with a certain geometric head under a certain load, and determines the hardness value according to the degree of indentation.

Commonly used methods are Brinell hardness (HB), Rockwell hardness (HRA, HRB, HRC) and Vickers hardness (HV).

3. Fatigue

The strength, plasticity and hardness discussed above are the mechanical properties of a metal under static load. In fact, many mechanical parts work under cyclic loads, in which case the parts will fatigue.

4. Resilience

The load acting on the machine at a high speed is called the impact load, and the ability of the metal to resist damage under the impact load is called the impact toughness.

Step 5: Intensity

Strength refers to the ability of a metal material to resist failure (excessive plastic deformation or fracture) under static load. Because the mode of load action has the form of tension, pressure, bending, shear and so on, the strength can also be divided into tensile strength, compressive strength, bending strength, shear strength and so on. There is always a certain relationship between various strengths, and tensile strength is the basic strength index in use.