1. Impact toughness of large-diameter steel pipes Galvanized square pipes: The load acting on the machine parts at a very high speed is called impact load, and the ability of metal to resist damage under impact load is called impact toughness.

2. Strength of large-diameter steel pipes: Strength refers to the performance of metal materials to resist damage (excessive plastic deformation or fracture) under static load. Since the load acts in the form of tension, compression, bending, shearing, etc., the strength is also divided into tensile strength, compressive strength, bending strength, shear strength, etc. There is often a corresponding connection between various strengths, and tensile strength is generally used as a more basic strength indicator in use.

3. The distinction between seamless and welded large-diameter steel pipes: Large-diameter steel pipes are formed by extruding seamless round pipes.

4. Plasticity of large-diameter steel pipes: Plasticity refers to the ability of metal materials to produce plastic deformation (long-term deformation) without damage under load.

5. Fatigue of large-diameter steel pipes: The strength, plasticity, and hardness discussed above are all indicators of the mechanical properties of metals under static loads. Many machine parts work under cyclic loads, and in such conditions, parts will produce fatigue.

6. Hardness of large-diameter steel pipes: Hardness is an indicator to measure the hardness of metal materials. At present, the commonly used method for measuring hardness in production is the indentation hardness method, which uses a corresponding geometric shape of the indenter to press into the surface of the tested metal material under the corresponding load, and determines its hardness value according to the degree of indentation.