Square tube according to the production process: hot-rolled seamless square tube, cold-drawn seamless square tube, extruded seamless square tube, welded square tube.
Welded square tube is divided into:
(a) by process - arc welding square tube, resistance welding square tube (high frequency, low frequency), gas welding square tube, furnace welding square tube
(b) according to the welded seam - straight seam welded square tube Spiral welded square pipe, square pipe according to section shape classification:
(1) simple section square pipe - square square square pipe, rectangular square pipe
(2) complex section square pipe - flower-shaped square pipe, open square pipe, corrugated square pipe, shaped square pipe Hardness is a measure of the degree of soft and hard metal materials pointer. Currently in production to determine the hardness of the most commonly used method is the indentation hardness method, which is a certain geometric shape of the indenter under a certain load pressed into the surface of the metal material being tested, according to the degree of being pressed into the determination of its hardness value.
Commonly used methods are Brinell hardness (HB), Rockwell hardness (HRA, HRB, HRC) and Vickers hardness (HV) and other methods. Strength is the performance of a metallic material to resist damage (excessive plastic deformation or fracture) under static load. Due to the way the load acts in the form of tension, compression, bending, shear, etc., so the strength is also divided into tensile strength, compressive strength, bending strength, shear strength and so on. There is often a certain connection between the various strengths, the use of tensile strength is generally more as the most basic strength pointer.