The surface compressive stress characteristics of the square tube will be obtained after isothermal quenching.
2After the sample is flattened to the specified flattening distance h， remove the load and remove the sample.
rCarbon steel classified by chemical composition: square tube A. low carbon steel (C & le; .%); b. Medium carbon steel (C & le; . ~ .%); c. High carbon steel (C & le; .%).
Spray fluorocarbon paint after.
PBatugayaTo change the required line shape of qb square tube， it is necessary to forge the impact force of qb square tube hammer or the pressure of hydraulic press， and can also enhance the malleability of qb square tube， that is， the performance of changing the shape without cracks.
HiHigh hardness square tubes mainly bear fatigue load，Q345D square tube so they must have high hardness. Therefore，Galvanized spiral pipe manufacturerLook quenching， surface quenching or chemical heat treatment shall be carried out， followed by low-temperature tempering treatment.
Yield point of square tube (& sigma; s): the stress of metal material with yield phenomenon when the sample can continue to elongate without increasing (maintaining constant) the force during the tensile process， which is called the yield point. If the stress decreases， the upper and lower yield points shall be distinguished. The unit of yield point is nmm (MPA).
Mechanical polishing: after processing， the parts have good levelness， short gloss， dull and rusty. Suitable for processing simple parts， medium and small products.
rAfter chemical pickling，Q345D square tube so that the square tube can bring us great help in the use process. The cold galvanized square tube is the principle of cold galvanizing on the square tube used to make the square tube have corrosion performance. Different from hot-dip galvanizing， cold galvanizing coating is mainly carried out according to the electrochemical principle. Therefore， it is necessary to ensure the sufficient of zinc powder and steel resulting in electrode potential difference， so the steel surface treatment requirements are very high.
YSquare 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， which is called square pipe.
NQuotation sheetDrawing process flow of square tube in the production process of square tube， it needs a lot of processes to complete the production process， so that the production quality of square tube can be more strictly guaranteed. This paper mainly introduces the drawing process flow of square tube. Lets understand it below.
lBThe quality of the solid square tube after the square tube formwork removal and curing can be tested according to the requirements and the following ways: use a magnifying glass to observe whether there are non external force cracks on the structural surface of the solid seamless qb square tube. When non external force cracks appear on the surface of qb square pipe， the crack width on the structural surface of ordinary qb square pipe shall not be greater than .mm.
， the blank holder area is insufficient， which easily leads to instability wrinkle; If the fillet is too small，Q345D square tube the resistance of the material into the die will increase in the deformation process， and the material is not easy to move and transfer inward，Galvanized spiral pipe manufacturerLook thus increasing the large tensile stress in the force transfer area， which may lead to tensile cracking.
Large diameter welded square pipe for low pressure fluid transmission， Standard No.: gbt-. Representative material: qab grade. It is mainly used to transport low-pressure fluids， such as water， sewage， gas， square tubes are used in more and more fields. So how can we correctly select the square tube? Let me introduce the process of the lower tube.
QCarbon steel classified by chemical composition: square tube A. low carbon steel (C & le; .%); b. Medium carbon steel (C & le; . ~ .%); c. High carbon steel (C & le; .%).
The standard quantity of combustible and nonflammable square tubes is gbt- (gbt-). The representative material is l-l pipeline steel. It specializes in selling square tubes rectangular tubes， seamless square tubes，Galvanized pipe_ Galvanized square pipe_ Seamless steel pipe_ Square tube - Wuxi Jiahang galvanized square tubes and galvanized tubes， with large quantity， high quality and low price. It is fire-resistant， waterproof， high temperature resistant， durable， safe and reliable. It is mainly used to transport combustible and nonflammable fluids， with high requirements.
aIn the test， place the sample between two parallel plates and press it evenly to the flattening distance h specified in relevant technical conditions with a press or testing machine at a speed of no more than mmin.
kPFor seamless qb square tubes there is a certain hardness， so there are still many for bearing in application， so it is necessary to test the mechanical properties of seamless qb square tubes.
Brinell hardness， Rockwell hardness and Vickers hardness are commonly used.