With the development of the national economy and the improvement of people's living standards.Spiral welded pipe has become a new trend in the development of domestic pipeline system. The company has always believed in "quality, customer first, sincere friends, and technology to prosper".The philosophy of Hebei Tianyuan Steel Pipe Manufacturing Co., Ltd. is "cooperation, innovation, progress and development".Since our company was founded.We always pay attention to the quality of products and the processing management of difficult products, and at the same time, we undertake various difficult processing and production of welded pipes.Realize user value.Is our goal.Difference between spiral welded pipe and longitudinal welded pipe metallurgical properties of materials longitudinal submerged arc welded pipe is produced from steel plate.The spiral welded pipe is produced by hot rolling coil. Quality requirements of steel pipes Surface quality of steel pipes: surface smoothness requirements a. Dangerous defects: cracks, internal folds, external folds, crushing, delamination, scabs, sags, bulges, etc.General defects: pockmarks, green lines, scratches, bruises, slight inner and outer straights, roll marks, etc.Cause: It is caused by surface defects or internal defects of the tube blank.During production, such as incorrect rolling process parameter design, unsmooth die surface, poor lubrication conditions, and unreasonable pass design and adjustment.In the process of heating, rolling, heating and straightening of pipe blanks (steel pipes), if excessive residual stress is generated due to improper control of heating temperature, uneven deformation, unreasonable heating and cooling speed or too large straightening deformation, surface cracks may also occur on the steel pipes. S355J2 is a European standard hot-rolled structural steel product, and other materials in the same series such as S355JO. C：≤0.22；Si：≤0.55；Mn：≤1.60；P：≤0.025；S：≤0.025；Cu：≤0.55；
S355 is a European standard low alloy high-strength plate Compared with fully quenched gcr15 steel bearing, the life of gcr4 steel bearing is significantly improved, which can be used for heavy haul high-speed train bearings.In the future, bearing steel should be developed in two directions of high cleanliness and functional diversification.Improving the cleanliness of bearing steel, especially reducing the oxygen content in steel, can significantly extend the life of bearings.The oxygen content decreased from 28 ppm to 5 ppm, and the number of exhausted lives could extend by an order of magnitude.In order to extend the life of bearing steel, people have been devoting themselves to developing and applying refined skills to reduce the oxygen content in steel for many years.Through unremitting efforts, the oxygen content in bearing steel has dropped from 28 ppm in the 6th century to 5 ppm in the 9th century.
The steel grade shall consist of the following parts:
- The standard number (EN10025-2);
- Steel name or steel grade: steel name consists of the following parts:
- Symbol letter S (structural steel) or E (engineering steel);
- Description of yield strength in MPa for thickness ≤ 16mm;
- When feasible, mark the name of the mass composition of the impact energy;
- where practicable, letters marked for special purposes;
- If the product is delivered in "+N or+AR" status, it must be marked with "+N or+AR". 1. Fake and inferior rectangular tubes are prone to folding.Folding is a variety of broken lines formed on the surface of rectangular tubes.This defect often runs through the longitudinal direction of the whole product.The reason for folding is the pursuit rate of fake and inferior manufacturers.The reduction is too large.Ears.Folding occurs during the next rolling.Folded products will crack after bending.The strength of steel is greatly reduced.2. The appearance of fake and inferior rectangular pipes is often pitted.Pitted surface is an irregular and uneven defect on the steel surface caused by serious wear of rolling grooves.Because the manufacturers of fake and inferior rectangular tubes want to pursue profits.Trough rolling often exceeds the standard.3. The surface of fake and inferior rectangular tubes is easy to produce scars.There are two reasons: (1). The material of fake and inferior rectangular tubes is uneven.There are many impurities.
This product is non corrosive, non combustible, non explosive, easy to use, transport and storage#The thermal process quenching and tempering of (No.) steel and 4Cr steel is the dual heat of quenching and high temperature tempering, which aims to make the workpiece have good comprehensive mechanical properties.The quenched and tempered steel includes carbon quenched and tempered steel and alloy quenched and tempered steel. Whether it is carbon steel or alloy steel, its carbon content is strictly controlled.If the carbon content is too high, the strength of the quenched and tempered workpiece is high, but the toughness is not enough. If the carbon content is too low, the toughness is increased and the strength is not enough.In order to obtain good comprehensive performance of quenched and tempered parts, the carbon content is generally controlled at. 3~5%.During quenching, tempering and quenching, the whole cross section of the workpiece is required to be fully quenched, so that the workpiece can obtain a microstructure dominated by fine needle quenched martensite.
