Square pipe, also known as square and rectangular cold-formed hollow section steel, is referred to as square pipe and rectangular pipe for short. The allowable deviation of wall thickness of square pipe is f and J q355b respectively. When the wall thickness is no more than 10mm, it shall not exceed plus or minus 10% of the nominal wall thickness. Long term square pipe, rectangular pipe seamless square pipe, galvanized square pipe, galvanized pipe, 20-year-old brand, price advantage and quality guarantee! When the wall thickness is greater than 10mm, it is plus or minus 8% of the wall thickness, except for the wall thickness of corners and weld areas.
The normal process flow is as follows: the round steel is perforated to form a tube embryo, then pickling is carried out, the black skin on the outer surface is washed off, and then grinding is carried out. After passing the inspection, the rolling mill or cold drawing and cold drawing are carried out. Annealing is required for wall reduction, but not for air drawing. After forming, annealing and straightening are carried out, and pickling is tested and stored in the warehouse. Basically, these are the processes. Better manufacturers will perform whitening treatment during annealing to make the surface treatment more beautiful. The narrow blank of square pipe can produce welded pipe with larger diameter, and the blank of the same width can also produce welded pipe with different diameter. However, compared with the straight seam square pipe with the same length, the weld length increases by 60%, and the production speed is low. Square pipes with large or thick diameter are usually made of steel blank directly, while small welded pipes and thin-walled welded pipes only need to be directly welded with steel strip. Then after simple polishing, wire drawing is OK. Therefore, straight seam welding is mostly used for relatively welded pipes, we should give full play to the productivity of production equipment and reduce the consumption of fuel and equipment on the basis of meeting the size and performance requirements of q355b square tube. Therefore, the temperature of no open forging and final forging is a comprehensive technical and economic problem. If qualified q355b square tubes can be obtained in the temperature range of the vehicle, reasonable process procedures should be selected from an economic point of view. Obviously, the higher the temperature, the easier the forging and the higher the productivity but the greater the fuel consumption and the loss of the heating furnace; We should consider these two aspects and make a reasonable choice.
.In the standard of q355b square tube, most of them specify tensile test and hardness test at the same time. For those materials that are not convenient for hardness test, such as q355b square tube, only tensile test is specified. In particular, the new portable surface Rockwell hardness tester and pipe Rockwell hardness tester can quickly and accurately test the hardness of stainless steel plate, stainless steel strip and q355b square tube as thin as 0.05mm, which makes it easy to solve the problems that were difficult to solve in China in the past.
One of the steps that are prone to defects in the production of square tubes is heat treatment and the other is tensile treatment. Today we need to know the latter. Maybe some people will have a lot of questions about why square tubes are prone to defects in tensile. Now let's analyze the specific causes of defects.
The tensile test is to make q355b into a sample, only tensile strength and then measure one or more mechanical properties. Usually, yield strength, tensile test has become the only means to test mechanical properties.
The square tube is formed by external control or internal control roller.
During the pushing process of spot welding and repair welding elbows, there will be thinning, so manufacturers usually use thick spot pipes. If thin raw materials are used, the products produced must be unqualified. Generally, there are about 40 wires thinned. If the technology is not good or the drawn pipe is used, the thickness is significantly lower than the standard.
Upper yield point (& sigma; Su): the large stress before the yield of the sample occurs and the stress decreases for the first time; Lower yield point (& sigma; SL): the small stress in the yield stage when the initial instantaneous effect is not considered.
Excellent service.After perforation, the round tube blank is successively rolled by cross rolling, continuous rolling or rolling. Take off the pipe after sizing. The conical drill bit of the sizing machine rotates into the steel embryo at high speed to form a steel pipe. The inner diameter of the steel pipe is determined by the outer diameter length of the sizing machine bit. After sizing, the steel pipe enters the cooling tower for water spray cooling. After cooling, which depends on the chemical composition and heat treatment of steel. In the steel pipe standard, according to different service requirements, the tensile properties (tensile strength, yield strength or yield point,WaterlooRust proof galvanized square pipe, elongation), hardness and toughness indexes, as well as the high and low temperature properties required by users are specified.
The cut-off position shall match the construction and site conditions, draw the determined position and mark the cut-off line with a meter ruler or other measuring tools.
Tensile strength of square tube (& sigma; b): the stress (& sigma;) obtained by dividing the force (FB) borne by the sample during breaking by the original cross-sectional area (so) of the sample during stretching, which is called tensile strength (& sigma; b), and the unit is nmm2 (MPA). It represents the large capacity of metal materials under tension.
Professional is king.Stainless steel q355b square pipe for mechanical structure, Standard No.: gbt12770-1991. Representative material 0Cr 1cr1 00cr19ni 1Cr18Ni 0cr18ni11nb, etc. It is mainly used for machinery, automobile, bicycle,Waterloo700 square tube, hotel and restaurant decoration and other mechanical parts and structural parts.
Solution treatment and nondestructive testing sand rolling treatment and sand blasting treatment many manufacturers in the market do not do solution treatment and 100% penetration nondestructive testing,WaterlooPrice of square galvanized steel pipe, and many of them use sand blasting instead of sand rolling. After these steps are omitted, the cost is greatly reduced.
Square pipe is an important pipe. Its application in various fields has different performance. According to its different performance, we have carried out different transformation on the other pipe to ensure that the square pipe can be better used. We should make the right choice when purchasing. Below I will introduce the correct way of painting the lower pipe.
Waterloo.When the square tube is processed, it needs to be properly polished to ensure durability, smoothness and. There are kinds of polishing for general stainless steel profiles, including mechanical polishing chemical polishing and electrochemical polishing.
After chemical treatment and surface treatment of the square tube, the appearance and quality of the square tube have been improved to another height, making the current square tube present in the market in a good state.
First, remove the deposits on the surface of the square pipe surface with copper wire brush. Use the perfume oil or other scrubbing oil on the surface layer, or use phosphate or chromate solution, brush, spray or dip coating. After the fixed reaction time, rinse the acid solution with plenty of fresh water on the surface.