1. Hot rolled extrusion seamless steel pipe : Round Tube > 3 > heating > perforated roller rolling, rolling or extrusion > > set off pipe diameter (or reducing) > cooling > > straightening pressure test or testing > mark > storage

2. Cold drawn (rolled) seamless steel pipe: round tube perforation > heating > > > Heading > pickling > oiled annealing copper > multi-pass cold drawn > Preform > heat treatment > Straightening > hydraulic pressure test testing > mark > storage

Mechanical Properties

Mechanical properties of steel is to ensure that end-use properties of steel mechanical properties of the key indicators, it depends on the steel's chemical composition and heat treatment. In the steel standards, based on different usage requirements to the tensile strength properties tensile strength, yield strength or yield point, elongation and hardness, toughness index, as well as users demand high and low temperature capabilities. 



i. Tensile strength

Sample in the tensile process, the pull off the most vigorously when exposed (Fb), out to sample the original cross-sectional area (So) from the stress , called the tensile strength , units N/mm2 (MPa). It said the role of metal material in the tensile resistance to failure under the maximum capacity. The formula is:

Type in: Fb - pull off when the sample is exposed most strongly, N (Newton); So - the original specimen cross-sectional area, mm2. 

ii. Yield point

Yielding of metal materials with the specimen during the tensile force does not increase (remain constant) could continue to stretch the stress, called yield point. If the drop occurs when the force should distinguish between the upper and lower yield point. Yield point of the unit N/mm2 (MPa).

The yield point : sample occurred before the first drop power yield and maximum stress; lower yield point : When excluding the initial transient effect, the yield phases of minimum stress.

Yield point is calculated as:

The formula: Fs - the process of tensile yield strength (constant), N (Newton) So - the original specimen cross-sectional area, mm2. 

iii. Elongation

In tensile testing, fractured by the increase in its gauge length and the percentage of the original gauge length, referred to as elongation. With that as%. The formula is:

The formula: L1 - fractured the gauge length, mm; L0 - the original specimen gauge length, mm. 




vi. section shrinkage

In the tensile test, the fractured cross-sectional area of its necking Department to reduce the maximum amount of the percentage of the original cross-sectional area, known as section shrinkage. To that as%. Calculated as follows:

Type in: S0 - the original specimen cross-sectional area, mm2; S1 - fractured necking Department at least cross-sectional area, mm2. 

v. hardness index

The hard metal object against the surface of the capacity of indentation, known as the hardness. According to different test methods and scope of application, can be divided into Brinell hardness, Rockwell hardness, Vickers hardness, Shore hardness, microhardness and high temperature hardness. Commonly used for the pipe are Brinell, Rockwell, Vickers hardness of three.

A, Brinell hardness (HB)

With a certain diameter carbide ball or a ball, to provide the test force (F) onto the pattern surface, removable by the provisions of time after the test force, indentation diameter measurement surface of the sample (L). Brinell hardness test force is obtained by dividing the indentation of spherical surface area business. With HBS (ball) that, in units of N/mm2 (MPa).

The formula is:
The formula: F - pressed into the metal surface of the sample test force, N; D - test with steel ball diameter, mm; d - the average diameter of indentation, mm.

More accurate and reliable determination of Brinell hardness, but in general HBS is only applicable to 450N/mm2 (MPa) below the metal material, the harder the steel or thin sheet does not apply. Standards in the steel, Brinell hardness most widely used and often indentation diameter d to represent the hardness of the material, both intuitive, and convenient.

For example: 120HBS10/1000130: 10mm diameter, said steel ball in 1000Kgf (9.807KN) Test Forces maintain 30s (seconds) measured Brinell hardness value of 120N / mm2 (MPa).

seamless steel weight formula

Seamless steel tube weight kg / m = (Od - Wt) * Wt * 0.02466 which is the outer diameter Od is the wall thickness Wt
Seamless process

Sanitary Mirror Tube Process:

Tube - Inspection - Skinning - Testing - Heating - perforation - Pickling - grinding - dry lubricant - welding head - cold drawn - solution treatment - Pickling - Pickling Passivation - test - cold - to oil - the first cut - dried - in polish - outside polished - test - identification - product packaging

Industrial Management Process

Tube - Inspection - Skinning - Testing - Heating - perforation - Pickling - Revised mushrooms - dry lubricant - welding head - cold drawn - solution treatment - Pickling - Pickling Passivation - test
Seamless steel pipe dimensions and tolerances