Due to the interaction between chromium and carbon in martensitic chromium nickel square tube， stable R phase region and stable a + R phase region are formed at high temperature. The increase of carbon content can expand the R-phase region， but the dissolution limit of carbon decreases with the increase of chromium content. The addition of nickel to martensitic chromium nickel square tube solves the problem that the hardness of steel is sacrificed to improve the corrosion resistance of martensitic square tube. However， the nickel content is not easy to be too high， otherwise the square tube will become austenite square tube due to nickel expanding austenite phase zone and reducing MS temperature， and then made by hot rolling，Rectangular Pipe cold rolling or cold drawing. Square pipe plays an important role in steel pipe industry.
lQb square tube，Galvanized square pipe quick connectorDetailed classification of qb square tube， qb square tube， QB square tube， QB square tube and hot-rolled right angle square tube are of good quality and excellent quality. We have become a supplier of many enterprises. Qb square tube and I-beam are two products with different shapes. Under the condition of the same material， the bearing capacity of steel is the same， but their uses are very different. The shape is different. Qb square tube is a cuboid， and I-beam is in I-shape. The purpose is different. I-beam can be used as span and support. Square pipe is a little worse than span. It is no problem to do support. However the specific selection of steel depends on the requirements of the project. Square tube practical application square tube for structure (gbt-) is a square tube for general structure and mechanical structure.
The difference between qb square tube and QA is that there are fewer impurities s and P and better low-temperature impact performance. From the welding point of view， when the impurity elements in the base metal are less， it is good for welding hot crack.
XHukmasSquare pipe is a square steel pipe cold drawn from seamless steel pipe，Rectangular Pipe which is not a straight qb square pipe， and qb square pipe， also known as welded pipe， is a square pipe welded by steel plate or strip steel after crimping. Qb square tube has the advantages of simple production process， high production efficiency， many varieties and specifications and less equipment. The commonly used materials are QA and QC.
NcAll seamless qb square tubes shall be tested for mechanical properties. Mechanical property tests are mainly divided into two categories: tensile test and hardness test.
The square tube represents the large capacity of the metal material under the action of tension， and the calculation formula is: where: FB -- the strong force borne by the sample when it is broken， n (Newton); So -- original cross-sectional area of sample， mm. Yield point (& sigma; s) the stress of metal material with yield phenomenon when the specimen can continue to elongate without increasing (keeping constant) the force during the tensile process， which is called the yield point.
Square tube industry plays an important role in production and construction. Square pipe is a steel pipe made of a whole piece of metal without joints on the surface，Rectangular Pipe which is called square pipe.
oSquare tube structural steel A. mechanical steel: (a) quenched and tempered structural steel; (b) Surface hardening structural steel: including carburized steel， ammoniated steel and surface quenching steel; (c) Easy to cut structural steel; (d) Steel for cold plastic forming: including steel for cold stamping and steel for cold heading.
CShot blasting and sand blasting are widely used in repair and shipbuilding industry. However，Galvanized square pipe quick connectorDetailed classification of whether shot blasting or sand blasting， square rectangular tubes， seamless square tubes， galvanized square tubes， galvanized tubes， high pressure rating， good waterproof performance fire resistance， high temperature resistance strong overload capacity，Galvanized pipe_ Galvanized square pipe_ Seamless steel pipe_ Square tube - Wuxi Jiahang corrosion resistance， radiation protection and long service life. Of course， it is not shot blasting that requires high-speed rotating impellers. In the repair and shipbuilding industry shot blasting (small steel shot) is mostly used in square pipe pretreatment (rust removal before coating); Sand blasting (mineral sand is used in repair and shipbuilding) is mostly used in formed ships or sections to remove the old paint and rust on the square tube and repaint it. In the repair and shipbuilding industry， the main function of shot blasting and sand blasting is to increase the adhesion of square tube coating paint.
FManufacturing costIt must be noted that in the overall process of square tube coating process， the cost of surface treatment is still relatively high， the surface effect of the square tube is quite good. The quality of the polishing process directly affects the external image of the square tube. Therefore， we must choose the appropriate polishing according to the above， and pay more attention to the polishing process of the square tube.
Functional index analysis of square tube - commonly used are square tube Brinell angle (HB)， Rockwell angle (HRC) and Vickers angle (HV). Angle is a gauge needle to weigh the soft and hard level of metal data. The angle method is rarely used to determine the internal angle in the current life. It uses the metal data surface tested under the fixed load of the indenter with a certain number and shape to determine its angle value according to the level of the object.
It belongs to flaw detector (or hydraulic test) for internal flaw detection. If there are cracks， bubbles and other problems inside the steel pipe， they will be detected. Steel pipes should be strictly selected manually after quality inspection. After the steel pipe is inspected， the number， specification， production batch number， etc. shall be sprayed with paint. And hoisted into the warehouse by crane.
Production departmentsToday， with the development of the world， all fields are coming rapidly， which makes the demand for square tube higher and higher， and the requirements of customers for square tube higher and higher. Now we are studying a new square tube. The following mainly introduces the performance of square tube in tensile strength.
LThe pressurization size and time are the key to the success or failure of welding. If the square tube synthetic material is not pressurized， a large number of pores will be caused due to the pores of the material itself and the gas generated in the reaction. It is not allowed to leave the reactants in the weld， so it must be densified， usually pressurized during the reaction.
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.
jIt is recommended that the galvanized surface be primed with epoxy zinc yellow primer.
mFHDPE plastic square pipe made according to the properties of square pipe has the advantages of light texture， high strength， good resistance， low water resistance， low cost and corrosion resistance. Its service performance and economic benefits far exceed reinforced concrete pipe and general specification iron pipe. It is an updated product of engineering pipe.
When the square tube is covered， the surface of the square tube shall be ventilated to avoid the collection of water vapor on the surface due to difficult volatilization.