Carbon steel pipe surface roughness

The surface roughness of carbon steel pipe refers to the small spacing and the unevenness of small peaks and valleys on the machined surface. The distance (wave pitch) between the two wave crests or two wave troughs is very small (below 1mm), which belongs to the micro-geometric error. The smaller the surface roughness of the carbon steel pipe, the smoother the surface.

The surface roughness of carbon steel pipe is generally formed by the processing method and other factors, such as the friction between the tool and the surface of the part during processing, the plastic deformation of the surface metal when the chips are separated, and the high-frequency vibration in the process system, etc. . Due to different processing methods and workpiece materials, the depth, density, shape and texture of marks left on the machined surface are different.

Surface roughness is closely related to the matching properties, wear resistance, fatigue strength, contact stiffness, vibration and noise of mechanical parts, and has an important impact on the service life and reliability of mechanical products. Ra is generally used for marking.

The influence of surface roughness on carbon steel parts is mainly manifested in the following aspects:

1. Affect wear resistance. The rougher the surface, the smaller the effective contact area between the mating surfaces, the greater the pressure, the greater the frictional resistance, and the faster the wear.
2. It affects the stability of cooperation. For clearance fit, the rougher the surface is, the easier it is to wear, so that the clearance gradually increases during the working process; for interference fit, due to the flattening of microscopic peaks during assembly, the actual effective interference is reduced. connection strength.
3. Affect fatigue strength. There are large wave valleys on the surface of rough parts, which are sensitive to stress concentration like sharp corner notches and cracks, thus affecting the fatigue strength of the parts.
4. Affect corrosion resistance. The rough surface of the parts easily allows corrosive gases or liquids to penetrate into the inner metal layer through the microscopic valleys on the surface, causing surface corrosion.
5. Affect the sealing. Rough surfaces do not fit tightly, and gas or liquid leaks through the gaps between the contact surfaces.
6. Affect the contact stiffness. Contact stiffness is the ability of the joint surface of a part to resist contact deformation under the action of external force. The stiffness of the machine is largely determined by the contact stiffness between the various parts.

7. Affect the measurement accuracy. The surface roughness of the measured surface of the part and the measuring surface of the measuring tool will directly affect the accuracy of the measurement, especially in the precise measurement.

In addition, surface roughness will have varying degrees of influence on the coating, thermal conductivity and contact resistance of parts, reflectivity and radiation properties, resistance to liquid and gas flow, and current flow on the conductor surface.