The seamless steel pipe is a steel pipe without weld seams produced by a perforated hot rolling method. It is sometimes necessary to further cold work the hot worked tube in order to obtain the corresponding shape and size. The carbon steel pipe is generally made into a round, square, flat shape by multiple rolling.
Seamless steel pipes are the most used pipes in today's petrochemical production plants. Carbon steel pipes
are more widely used. At the same time, the main requirement of the carbon steel pipe is its carbon content. The seamless steel pipe is a large type, and the steel pipe is seamless and has a wide range.
The mechanical properties of steel are generally expressed in the following aspects:
1. Yield point (σs)
When the steel or specimen is stretched, when the stress exceeds the elastic limit, even if the stress does not increase any more, and the steel or the specimen continues to undergo significant plastic deformation, the phenomenon is called yielding, and the minimum stress value when yielding occurs is
To yield points. Let Ps be the external force at the yield point s, and Fo be the sample cross-sectional area, then the yield point σs = Ps / Fo (MPa)
2. Yield strength (σ0.2)
Some metal materials have a very low yield point and are difficult to measure. Therefore, in order to measure the yield characteristics of the material, it is specified that the permanent residual plastic deformation is equal to a certain value (generally 0.2% of the original length). The yield strength or simply the yield strength σ0.2.
3. Tensile strength (σb)
The maximum stress value achieved by the material during the stretching process from the beginning to the time of the fracture. It indicates the ability of the steel to resist fracture. Corresponding to the tensile strength, there are compressive strength, bending strength, and the like. Let Pb be the maximum tensile force reached before the material is broken. Fo is the cross-sectional area of the specimen, and the tensile strength σb = Pb/Fo (MPa).
4. Elongation (δs)
After the material is broken, the length of the plastic elongation and the length of the original sample are called elongation or elongation.
5. Yield ratio (σs/σb)
The ratio of the yield point (yield strength) of the steel to the tensile strength is called the yield ratio. The higher the yield ratio, the higher the reliability of the structural parts. The general carbon steel yield ratio is 0.6-0.65, and the low alloy structural steel is 0.65-0.75 alloy structural
steel is 0.84-0.86.
6. Hardness Hardness indicates the ability of a material to resist the intrusion of a hard object into its surface. It is one of the important performance indicators of metallic materials. Generally, the higher the hardness, the better the wear resistance. Commonly used hardness indexes are Brinell hardness, Rockwell hardness and Vickers hardness.