Q355GNH straight seam welded steel pipe is a high-strength low-alloy structural steel welded pipe widely used in construction, bridges, machinery manufacturing, and other fields, with excellent mechanical properties and welding properties. As one of the important types, Q355GNH straight seam welded steel pipe occupies an important position in the market with its stable quality and reliable performance.
First, the characteristics of Q355GNH straight seam welded steel pipe
Q355GNH straight seam welded steel pipe uses Q355GNH steel plate as raw material and is made by high-frequency welding or submerged arc welding process. Q355GNH steel is a low-alloy high-strength structural steel, and its chemical composition and mechanical properties meet the requirements of the national standard GB/T 1591-2018 “Low Alloy High Strength Structural Steel”. This steel has good comprehensive properties, including high strength, good plasticity and toughness, and excellent welding performance.
The main features of Q355GNH straight seam welded steel pipe include:
1. High strength: The yield strength of Q355GNH steel can reach more than 355MPa, and the tensile strength is 470-630MPa, which can meet the strength requirements of most engineering structures.
2. Good welding performance: The carbon equivalent of Q355GNH straight seam welded steel pipe is low, it is not easy to crack during welding, and the performance of the welded joint is stable.
Second, the production process of Q355GNH straight seam welded steel pipe
The production process of Q355GNH straight seam welded steel pipe mainly includes the following steps:
1. Raw material preparation: A Q355GNH steel plate that meets the GB/T 1591-2018 standard is selected as the raw material to ensure that its chemical composition and mechanical properties meet the standards.
2. Steel plate pretreatment: The steel plate is pretreated by leveling, cutting, planing, etc. to ensure its dimensional accuracy and surface quality.
3. Forming: The steel plate is rolled into a tube by a forming machine to form the prototype of the straight seam welded pipe.
4. Welding: Use high-frequency welding (HFW) or submerged arc welding (SAW) to weld the edges of the steel plates together to form a complete welded pipe.
- High-frequency welding: Use the skin effect and proximity effect generated by the high-frequency current to quickly heat the edges of the steel plates to a molten state and achieve welding under pressure. High-frequency welding is fast and efficient and is suitable for the production of small and medium-diameter welded pipes.
- Submerged arc welding: The arc burns under the flux layer to achieve welding of the edges of the steel plates. Submerged arc welding has stable quality and is suitable for the production of large-diameter and thick-walled welded pipes.
5. Weld seam treatment: Remove burrs inside and outside the weld seam after welding, polish it, and ensure that the weld seam is flat and smooth.
Third, the application field of Q355GNH straight seam welded steel pipe
Q355GNH straight seam welded steel pipe is widely used in the following fields due to its excellent performance:
1. Building structure: Used for steel structure frames of large buildings such as high-rise buildings, gymnasiums, exhibition halls, etc., to provide stable support and load-bearing capacity.
2. Bridge engineering: used for bridge trusses, piers, guardrails, and other parts to bear the load of vehicles and pedestrians.
3. Machinery manufacturing: used for the skeleton and supporting structure of equipment such as engineering machinery, agricultural machinery, mining machinery, etc.
4. Shipbuilding: used for structural parts such as decks and bulkheads of ships, with good corrosion resistance and strength.
Fourth, the purchase precautions of Q355GNH straight seam welded steel pipe
When purchasing Q355GNH straight seam welded steel pipe, you should pay attention to the following points:
1. Material certification: require suppliers to provide quality certificates of raw materials to ensure that their chemical composition and mechanical properties meet national standards.
2. Production process: understand the production process of welded pipes, and give priority to products using high-frequency welding or submerged arc welding processes to ensure welding quality.
3. Appearance inspection: check whether the surface of the welded pipe is flat and smooth, whether there are defects such as cracks, pores, slag inclusions, and whether the weld is uniform.
4. Dimensional accuracy: measure the outer diameter, wall thickness, length, and other dimensions of the welded pipe to ensure that it meets the design requirements.
5. Nondestructive testing report: Suppliers are required to provide nondestructive testing reports of welds to ensure that their internal quality meets the standards.
Fifth, the market status and development trend of Q355GNH straight seam welded steel pipes
In recent years, with the rapid development of my country’s infrastructure construction, the market demand for Q355GNH straight seam welded steel pipes has continued to grow. Especially in the fields of construction, bridges, machinery manufacturing, etc., Q355GNH straight seam welded steel pipes have gradually replaced some seamless steel pipes and other low-alloy steel welded pipes due to their excellent performance and reasonable prices.
In the future, the development trend of Q355GNH straight seam welded steel pipes will be mainly reflected in the following aspects:
1. High performance: By optimizing the chemical composition and heat treatment process, the strength and toughness of Q355GNH steel will be further improved to meet higher requirements for engineering applications.
2. Green and environmental protection: Promote the use of environmentally friendly anti-corrosion coatings and galvanizing processes to reduce environmental pollution during production and use.
3. Intelligent production: Introduce automated and intelligent production equipment to improve production efficiency and product quality stability.
4. Application field expansion: With the development of new materials and the application of new processes, Q355GNH straight seam welded steel pipe will be used in more fields, such as new energy, rail transit, etc.
Sixth, Conclusion
Q355GNH straight seam welded steel pipe, as a high-performance structural steel welded pipe, plays an important role in construction, bridges, machinery manufacturing, and other fields. By understanding its characteristics, production process, application fields, and purchase precautions, users can better choose and use Q355GNH straight seam welded steel pipe to ensure project quality and safety. With the advancement of technology and the development of the market, the application prospects of Q355GNH straight seam welded steel pipe will be broader.
Post time: May-15-2025