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The Important Index Of Seamless Steel Tube
Oct 18, 2017



Seamless steel tube has a hollow section, a large number of pipelines used for conveying fluids, such as oil, gas, gas, water and some solid materials pipeline. Compared with solid steel such as round steel, the flexural and torsional strength is light weight, is an economic section of steel, Seamless Steel Pipes widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipe, automobile propeller shaft, bicycle racks and steel scaffolding used in construction, such as the production of circular parts steel pipe, Seamless Steel Pipes can improve material utilization, simplify manufacturing processes, Saving materials and working hours, has been widely used in steel pipe manufacturing.

The use of seamless steel tube is mainly two: mechanical processing pipe fluid transport. Other special tubes, etc.

The biggest difference between seamless steel tubes and other bars is that there is no seams around them, and the cross-section of steel tubes is hollow. Seamless Steel Pipes Because of the different cross-section shape, and often classified as circular steel pipe and the opposite sex steel pipe, from the actual use of efficiency, of course, is more common pipe-shaped pipe.

When it comes to the use of seamless steel tubes, we are most familiar with its natural gas, water and other daily use of fluid transport. In addition to these common and familiar shipments of natural gas and water, seamless steel tubes are widely used for transporting oil, Seamless Steel Pipes gas and certain solid materials. Seamless steel tube Transportation facilitates people's modern life, greatly reduces the transportation cost of natural resources.

Second, because the seamless steel tube hollow, its quality than the solid steel pipe to be much lighter, natural to be more economical and affordable, so in such as automotive transmission shaft, oil, such as drill pipe, bicycle racks and other manufacturing plays an important role in structural parts and components. It also reduces unnecessary waste of resources and reduces the total weight of finished products.

Apart from the times, seamless steel tubes are often used as raw materials for ring metal parts, not only to save a lot of complex processes, but also greatly reduce the production process of steel loss, to save production costs. This kind of processing principle is not difficult to understand, Seamless Steel Pipes a bit similar to cut the spinach, a knife cut down can quickly get one ring small ring parts, will minimize the loss.

Seamless steel tube Performance characteristics

The mechanical property of steel is an important index to ensure the final use performance (mechanical properties) of steel, which depends on the chemical composition and heat treatment system. In the steel pipe standard, according to different use requirements, the tensile performance (tensile strength, yield strength or yield point, elongation) and hardness, toughness index, as well as user requirements of high, Seamless Steel Pipes low temperature performance.

① tensile strength (σb)

During the tensile process, the specimen is subjected to a larger force (FB), divided by the stress (σ) obtained by the original cross-sectional area (so) of the specimen, called the tensile strength (σb), and the Unit is n/mm2 (MPa). It indicates that the metal material can resist the damage under the tensile force.

② yield Point (σs)

In the case of metallic materials with yielding phenomena, the stress of the specimen during the tensile process is not increased (constant), and the yield point is also maintained. If the force is reduced, the upper and lower yield points should be differentiated. The unit of the yield point is n/mm2 (MPa).

The upper yielding point (ΣSU): The larger stress before the specimen is yielded and the force first decreases; the lower yield point (ΣSL): When the initial instantaneous effect is disregarded, the minimum stress in the yield phase is taken.

The formula for the yield point is:

In the formula: The yield force (constant) in the tensile process of fs--specimen, Seamless Steel Pipes the original cross-sectional area of N (Newton) so--specimen, mm2.

Elongation rate (σ) after ③

In tensile test, the percentage of the length of the specimen and the length of the original standard distance is called elongation rate. In σ, the unit is%. The formula is: σ= (Lh-lo)/l0*100%

In the formula: lh--specimen pull the mark distance length, mm; l0--specimen original standard distance length, MM.

④ section Shrinkage Rate (PSI)

In tensile test, the reduction of the cross-sectional area of the specimen and the percentage of the original cross-sectional area are called the sectional shrinkage rate. In the case of PSI, the unit is%. The calculation formula is as follows:

In the formula: the original cross-sectional area of the s0--specimen, the mm2, Seamless Steel Pipes the minimum cross-sectional area of the s1--specimen, and the mm2.

⑤ Hardness Index

The ability of metal materials to withstand hard surfaces is called hardness. According to the test method and the scope of application, hardness can be divided into Brinell hardness, Rockwell hardness, Vickers hardness, shore hardness, microhardness and high-temperature hardness. For the general use of pipe has Brinell, Rockwell, Vickers hardness three kinds.

A, Brinell hardness (HB)

With a certain diameter of steel ball or cemented carbide ball, the specified test force (F) is pressed into the design surface, the test force is removed after the prescribed retention time, Seamless Steel Pipes and the indentation diameter of the specimen surface is measured (L). Brinell hardness is the quotient of the experimental force divided by the spherical surface area of the indentation. With HBS (steel ball) indicated, the unit is n/mm2 (MPa).


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