Copper Tube Information

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3 4 brass square tube

author:MF manufacturerstime:2022-03-09 13:04:49

1.Square tube


Square tube,It is a tube type of a seed,Is a hollow square cross-sectional light thin-walled steel pipe,Also known as steel refrigeration curved profiles。It isQ235Hot rolled or cold-rolled steel or roll plates for the base material after the cooled bending, the shape of a square cross-sectional steel made of high frequency welding。


Square use of the building,Machine made,Steel construction and other projects,shipbuilding,Solar power generating bracket,Steel structure engineering,Power Engineering,Power plant,Agriculture and chemical machinery,Glass curtain wall,Car chassis,Airport,Boiler construction,Highway railing,construction,Pressure vessel,Oil storage tank,bridge,Power plant equipment,Lifting transport machinery and other higher load welding structures, etc.。Very wide。


Two types of ordinary carbon steel and alloy steel,Therefore, there are two kinds of copper-carbon steel square tubes and low alloy squares.。Carbon steelQ195、Q215、Q235、SS400、20#steel、45#Steel, etc.;Low alloy steelQ345、16Mn、Q390、ST52-3Alienate。

(3 4 brass square tube)Four、Production Process

Material selection---Material examination---Material storage-----Roller extrusion molding----Straighten----Job check,Intermediate check-----Heat treatment---Mechanical performance test----Chemical analysis---Stretching test-----Product storage---Finished examination----product in stock

3 4 brass square tube



Plasticity means metal materials under load,Plastic deformation(Permanent deformation)Not destroying。


Hardness is a pointer to measuring the softness of metal material。The most commonly used hardness method is most commonly used in production in production.,It is the surface of the tested metal material surface under a certain load with a certain geometric shape.,Determine its hardness value according to the degree of pressing。

Commonly used methods have a cloth hardness(HB)、Rockwell hardness(HRA、HRB、HRC)And Vickers hardness(HV)Method。


The intensity discussed earlier、Plasticity、Hardness is the mechanical performance pointer of metals under static load。Actually,Many machine parts are working under a circulatory load,The parts are fatigued under this condition.。

Impact toughness

Loads acting on the machine with a very large speed are called impact loads,The ability to resist damage under impact load is called impact toughness。


The strength means that the metal material is resistant to damage under astostat.(Excess plastic deformation or break)Performance。Due to the mode of operation, there is stretching、compression、bending、Shear and other forms,Therefore, the strength is also divided into tensile strength.、Compressive strength、Anti-bending strength、Shear strength, etc.。There is often a certain connection between various intensities,Usually more than tensile strength as the most basic intensity pointer。

six、Molding method

1、Solid bend

Solid bend,As the name suggests is constructed,During the curved, the inside and outside rolls and the inner and outer walls of the tube are compact。

1)The advantage of solid bend is the rebound,Accurate formation,And as long as the roll is accurate,Inner-angledRMore accurate。

(3 4 brass square tube)2)The disadvantage of solid bend is to stretch/Thin effect。First,The real bend will cause the bend to produce stretching,The tensile effect is shortened by the longitudinal length of the bending line.; second,The metal bending metal will thinner due to stretching。

2、Empty bend

Empty bending is to form a bending moment by a one-way contact with the outer wall of the tube blank,Empty bend will cause the bending line to compress,The compression effect makes the bending line longitudinally elongate,Bending metal has a stacked thickness,This is the compression of empty bend/Thickening effect。

(3 4 brass square tube)1)The advantage of the empty bend is that the side length bending can be performed when bent,Such as the upper side of the square tube/Side synchronous bending and finishing。Empty bending can be bentR<0.2tInner angle and does not break the tube wall。

(3 4 brass square tube)2)The disadvantage of the empty bend is on the side/Side synchronization empty bend,Due to the upper roller and the lower roller,Minding force is easy to transcend critical point,Caused by endostability,And also affect the stable operation and quality of the unit。This is also the characteristic of the square tube and the round tube empty bending.。

seven、Save tips

1)first,We should choose a suitable venue or a warehouse to use the storage location of the square tube.,Should be selected in clean、Drainage,Do not be with the acid during storage、Base、Salt、Cement and other corposed materials have an aggressive material。

(3 4 brass square tube)2)Secondly,We have to pay attention to stack when storing,In the case of ensuring safety,Pay attention to the high pad、Three key points of sturdy peace,Separate storage of different species specifications,The artificial operation does not exceed1.2m,Mechanical operation does not exceed1.5m,The width is not more than2.5m。

Eight、Inspection standards

1)Sign、Packaging check:1.Products should have a sign representing the direction of production or installation,Should be indicated、trademark、Product standard remember、colour、Batch number of production date。2. Each batch of product certificate and packing list。There should be the following:company name;product name;Product specifications;Production batch;Check results and inspection department seals。 The box should have the following:company name;product name、colour;Product mark;Production batch;merchandise quantity;Packaging date。

2)Exterior:1.No bubbles on the surface、crack、Scar、Crack and inclusions,No layering;2.The surface allows the following defects that are not greater than the minimum thickness of the square tube within half the range of thickness tolerances:Lightweight sparrow and local deep numb、Small bubble、Small pull、Scratch、Mild scratches and roll indentation。Allow local blue oxide color。

3)Dimensions and allowed deviations:According to the supplier's technical document,Quality certificate GB/T 702-2008

2.Classification of square tube

1.Classification by square tube production process:

Hot rolling seamless square tube、Cold pull seamless square tube、Squeezed seamless square tube、Welding square tube。Among them, the welding tube is divided into:(a)According to process——Arc welding、Resistance welding square tube(high frequency、Low frequency)、Gas welding、Furnace welder(b)Search according to weld——Straightened welding square、Spiral welding square tube

2.Pipe material:

(3 4 brass square tube)Puocarbon steel square tube、Low alloy square tube。

3.Based on the manifold:

(1)Simple cross section——Square square tube、Rectangular square tube

(2)Complex section——Floral square tube、Open-way、Corrugated square tube、Profile。

4.Classified by use

Pipeline、Hot work equipment、Mechanical industrial、Chemical industry、Marine square tube、Construction engineering、Steel structure square tube、Special use square tube、Decorative、Machine tool equipment、Shipping square tube、Automotive、Steel beam column。

3 4 brass square tube

5.Classification by square tube surface:

Hot-dip galvanized square、 Electroplated zinc square、Oil、Wash square tube

6.Classification of wall thickness:

Super thick wall tube、Thick wall square tube and thin wall tube

7.Classified according to production standards:

(3 4 brass square tube)National standard,Daily label,British square tube,Beautiful label tube,European standard,Non-standard square tube。

8.Classified by mechanics:

Steel square control mechanism is to ensure the performance of the square tube(Mechanical behavior)Important indicator,It depends on the chemical composition and heat treatment system of square tube steel。In square tube standard,According to different requirements,Tensile performance(tensile strength、Yield intensity or yield point、Elongation)And hardness、Toughness indicator,There is also the high requirements of the user、Low temperature, etc.。therefore,High performance square tube、Central energy square tube and low performance square tube。

3.Common square tube specifications and theoretical weight calculation formula

(3 4 brass square tube)Specifications method for square tube:Mainly with side wide*Edge width*Tube wall thickness。Such as16×16×0.4~1.5The marking edge is16mm,Tube wall thickness0.4-1.5mm。Use the word type to identify symbol。

Specification Table:

3 4 brass square tube

3 4 brass square tube

3 4 brass square tube

3 4 brass square tube

Calculate formula:4xWall thicknessx(Edge length-Wall thickness)x7.85 in,Side length and wall thickness are in millimeters,Directize the value into the above formula,It is the weight of each mean tube.,Gram。Such as30x30x2.5Mm square tube,According to the above formula, it can calculate its weight per meter.:4x2.5x(30-2.5)x7.85=275x7.85=2158.75gram,I.e.2.16Kilogram

When the wall thickness and the side length are in millimeters,4xWall thicknessx(Edge length-Wall thickness)Calculated is the volume of the length of the length of each meter,Cubic centimeter,Take the proportion of iron per cubic centimeter7.85gram,The weight of the unit is based on gram per rice.。

4.Welding square tube


Welding square tube also known as welded pipe,Is a square tube that is prepared after the steel sheet or strip steel is being welded after curling。Typical ruler6Meter。Welding steel pipe production process is simple,high productivity,Very variety,Equipment investment,But general intensity is lower than seamless steel pipe。

two、Manufacturing process

(3 4 brass square tube)Welding square tube with narrow billet production pipe diameter solder pipe,It is also possible to produce non-different welders with the same width.。But compared to the seamless square tube of the same length,Weld length increases30~100%,And the production speed is low。

(3 4 brass square tube)Welding square tube with large or thicker diameter,Generally, the steel blanks are used directly.,And the small welded pipe thin wall welded pipe only needs to be directly welded through the steel belt.。Then pass a simple polishing,Brushed。therefore,The solder tube of smaller diameter is mostly seamless welding.,Large diameter welded tubes are mostly spiral welding。

three、Quality issues should be paid attention to

1)Size beyond allowed deviation:Welding length、width、Insufficient thickness,Central line offset,Bend and other deviations,The relative position size of the welding portion should be strictly controlled,Exquisite welding after passing,Welcomes carefully。

2)Weld cracked:To prevent crack production,Suitable welding process parameters should be selected and solder procedures,Avoid using large currents,Don't suddenly turn off,Weld joint should be lapsed10~15mm,No movement is not allowed in welding、Tap solder。

(3 4 brass square tube)3)Surface air hole:The electrodes are baking according to the specified temperature and time,Welding area must be cleaned up,Select appropriate welding current during welding,Reduce welding speed,Complete the gas in the molten pool。

4)Welding slag:Multi-layer welding should be cleaned,The operation should be correct in the operation,Curved length。Pay attention to the direction of flow of slag,When using alkaline electrodes,The slag must remain behind the slag。

3 4 brass square tube

Four、Deformation reasons

The deformation of the weld square is mainly caused by the weld shrinkage than the strength of the base material.。

(3 4 brass square tube)1)Only one-sided one weld,Use from the middle to start segmentation,which is:The second section of weld arc in the first paragraph。

2)Take less soldering wire energy,(Welding line energy is proportional to current,And reverse with welding speed),which is:Small welding current、Faster welding speed。

3)Symmetrical、Four weld,Start welding from one end,Two interleasing welding of symmetry。Alterate:First welding150mmLong-standing,Repair300mm,over the front150mm,After each welding300mm,every time you cross150mmspan。

(3 4 brass square tube)Fives、The difference between welded square tube and seamless square tube

1)seamless square tube,It is a steel pipe with four squares and four corners,Square steel tube formed by cold-drawn extrusion of seamless steel tube。

2)Welded square pipe is also called welded pipe,It is a square tube made of steel plate or strip steel after being crimped and welded.。

3)Better quality of seamless square tube,more expensive,Welded square tubes are made by bending the sheet,welded,High temperature during welding,High temperature affects the structure of metals,Mechanical properties are not as stable as seamless steel pipes。

4)Welded square tube is a hollow square section steel square tube,Also known as hollow cold-formed steel.It is made of hot-rolled or cold-rolled strip or coil as a blank, which is formed by cold bending and then welded by high frequency.。In addition to the thickening of the wall thickness of the seamless square tube,Its corner size and edge straightness reach or even exceed the level of resistance welded cold-formed square tubes,RThe size of the corners is generally the wall thickness2times-3between times。

5.Galvanized square tube


Galvanized square pipe is a hollow square section steel pipe with a square cross-section shape and size made of hot-rolled or cold-rolled galvanized strip steel or galvanized coil as a blank after cold bending and high-frequency welding.;Or a galvanized square rectangular tube made by hot-dip galvanizing of the cold-formed hollow steel pipe made in advance。


Since the galvanized square pipe is galvanized on the square pipe,Therefore, the application range of galvanized square pipe has been greatly expanded compared with square pipe.。It is mainly used for curtain wall,architecture,Machine made,Steel Construction Project,shipbuilding,solar power bracket,Steel structure engineering,Power Engineering,power plant,Agricultural and Chemical Machinery,Glass curtain wall,Car chassis,Airport etc.。

(3 4 brass square tube)In addition, the hot-dip galvanized square tube has good strength、toughness、Process properties such as plasticity and welding have good ductility,Its alloy layer is firmly attached to the steel base,Therefore, the hot-dip galvanized square tube can be cold punched、rolling、brushed、Various forming such as bending without damaging the coating;Suitable for general machining such as drilling、cut、welding、Cold bending and other processes。The surface of the parts after hot-dip galvanizing is bright and beautiful,Can be directly used in engineering as required。


1、Has a thick dense layer of pure zinc covering the steel surface,It avoids the contact of the steel substrate with any corrosive solution,Protects the steel substrate from corrosion。in normal atmosphere,A very thin and dense zinc oxide layer is formed on the surface of the zinc layer,it is hardly soluble in water,Therefore, it has a certain protective effect on the steel matrix。If zinc oxide and other components in the atmosphere form insoluble zinc salts,The anti-corrosion effect is more ideal。

2、has iron—Zinc alloy layer,binding dense,Unique corrosion resistance in marine salt spray atmosphere and industrial atmosphere;

3、Due to the firm bond,Zinc—Iron miscible,Has strong wear resistance;

4、Due to the good ductility of zinc,Its alloy layer is firmly attached to the steel base,Therefore, hot-dip galvanized parts can be cold-stamped、rolling、brushed、Various forming such as bending without damaging the coating;

5、After hot-dip galvanizing of steel structure,Equivalent to one annealing treatment,Can effectively improve the mechanical properties of the steel matrix,Stress relief during forming and welding of steel parts,Facilitates the turning of structural steel parts。

6、The surface of the parts after hot-dip galvanizing is bright and beautiful。

7、Pure zinc layer is the most plastic galvanized layer in hot-dip galvanizing.,Its properties are basically close to pure zinc,malleable,so it is flexible。

(3 4 brass square tube)3 4 brass square tube

Four、Comparison of Galvanized Square Pipe and Welded Square Pipe

Galvanized square pipe is one of the most corrosion resistant in the square pipe category,The material of its own two materials、Production process、And some square tube specifications are basically similar to the implementation standards,Since the galvanized square pipe is hot-dip galvanized on the basis of the welded square pipe,Therefore, the protective effect of galvanized square pipe is stronger than that of ordinary welded square pipe.,Strong corrosion resistance。It can be said that the whole structure of the hot-dip galvanized square tube is made of zinc,Formation of dense quaternary crystals,This crystal forms a barrier on the steel plate,Effectively prevent the penetration of corrosion factors。Corrosion resistance Strong barrier protection from zinc layer。when zinc is cutting edges、Scratches and coating scratches for sacrificial protection,Zinc forms an insoluble oxide layer,function as a barrier。Superior performance makes the application range of galvanized square pipe extremely wide,At the same time, it also promotes the expansion and demand of the market。

Welded square pipe is a name for square pipe,Welded square pipes are steel pipes with equal side lengths。But the welded square tube is divided according to the production process:Hot rolled seamless square tube、Cold drawn seamless square tube、Extruded seamless square tube。Welded square tube is rolled from strip steel after process treatment,Unpack first,flat,curly,Welded to form a round tube,It is then rolled into a square tube from a round tube and then cut to the required length。The round tube is then rolled into a rectangular tube by another process.,Because the welded square tube is formed by cold rolled strip,then it isQ235Hot-rolled or cold-rolled strip or coil is a section steel with a square cross-section shape and size made by high-frequency welding after cold bending of the base material.。Hot-rolled extra-thick-wall square tube except for thickening of wall thickness,Its corner size and edge straightness reach or even exceed the level of resistance welded cold-formed square tubes。Good comprehensive mechanical properties,Weldability,cold,Good hot workability and corrosion resistance,Has good low temperature toughness。

6.The difference between hot-dip galvanized square tube and cold-dip galvanized square tube

Galvanized square pipes are divided into hot-dip galvanized square pipes and cold-galvanized square pipes from the production process.。It is precisely because the processing of these two galvanized square pipes is different that they have many different physical and chemical properties.。In general they are strong、There are many differences in toughness and mechanical properties。Next, let's take a closer look at the differences。

1.color difference

The color of the hot-dip galvanized square tube is silvery white at a certain angle to the sun。

The color of cold galvanized square tube is yellowish green when it is at a certain angle to the sun、Blue-white or slightly colorful。

2.Zinc layer thickness difference

The inner wall and outer wall of the hot-dip galvanized square tube are attached with a zinc layer,There will be water streaks and a little zinc tumor,But the overall zinc layer is thicker,The thickness of the zinc layer on the inner and outer walls of the square tube is70μmabove。

Because the cold galvanized square tube and the hot-dip galvanized square tube are very different in the galvanizing process。The corners and edges of the cold galvanized square tube are easy to produce"electric burn"This part is dark,The zinc layer is thicker。It is easy to form a current dead angle in the inner corner, resulting in an undercurrent area,The zinc layer is thinner at this part,No zinc layer attached to the inner wall of the cold galvanized square tube。Cold galvanized square tube as a whole without zinc tumor、agglomeration, etc.,But the overall zinc layer is thinner,The thickness of the outer wall zinc layer is5μm-10μm。

3.Appearance difference

The appearance of hot-dip galvanized square pipe is slightly rougher than that of cold-dip galvanized square pipe。

The appearance of cold galvanized thick-walled spiral steel pipe is relatively smooth、bright。

(3 4 brass square tube)4.different production processes

Hot-dip galvanized square tube

(3 4 brass square tube)Hot-dip galvanized square tube:It is a square tube made of welded steel plate or steel strip after crimping.,And on the basis of this kind of square tube, the square tube is placed in the hot-dip galvanizing pool and formed by a series of chemical reactions.。The production process of hot-dip galvanized square pipe is relatively simple,And the production efficiency is very high,Variety and specifications,This square tube requires very little equipment and capital,Suitable for the production of small galvanized square pipe manufacturers。

Cold galvanized square tube

(3 4 brass square tube)The cold galvanized square pipe uses the principle of cold galvanizing on the square pipe used to make the square pipe have anti-corrosion properties.。Unlike hot-dip galvanizing, cold-dip galvanizing coatings are mainly used for anti-corrosion through electrochemical principles.,Therefore, it is necessary to ensure sufficient contact between zinc powder and steel,Generate electrode potential difference,Therefore, the surface treatment of steel is very important。

5.other different

(3 4 brass square tube)1)Hot-dip galvanized square tube,Longer corrosion resistance。Because the thickness of hot dip galvanized is usually thicker than that of cold galvanized,The zinc layer is more stable。And the hot-dip galvanized square tube is galvanized inside and outside,Many cold galvanized square or round pipes,Memory has no zinc layer,Rust easily from the inside。

(3 4 brass square tube)2)Hot dip galvanized zinc layer thickness,Strong anti-corrosion,但是外观比较粗糙。

3)But the appearance is rough,外观好,Cold galvanized,均匀,Good appearance,防腐性能要差很多。

High Brightness: