Q235B LSAW Steel Pipe DN700

Why Q235B material can be the preferred base material of LSAW steel pipe?

The core competitiveness of Q235B LSAW steel pipe originates from the excellent characteristics of Q235B material. As a general grade of carbon structural steel, Q235B material is not the steel with the highest strength and superior performance, but it is one of the most suitable substrates for LSAW process and the most practical engineering requirements. Its adaptability, economy and processability perfectly match the production characteristics of longitudinal submerged arc welding process and meet the core requirements of most projects for pipes, which is also the key reason why Q235B material has become the preferred substrate for LSAW steel pipe.

First of all, Q235B material has excellent welding performance, which perfectly meets the requirements of LSAW process. The core requirement of LSAW longitudinal submerged arc welding process is that the substrate has good weldability, and high-quality welding can be realized without complicated preheating and post-heating processes, so as to avoid cracks, pores and incomplete penetration in the weld. The carbon content of Q235B material is controlled below 0.20%, and the carbon equivalent is less than or equal to 0.3%, which belongs to the category of low carbon steel. The low carbon content greatly improves the weldability of steel, and it is not easy to produce hardened structure during welding. The fusion between weld and base metal is good, and the strength and toughness of welded joint can approach the level of base metal, so the welding quality requirements can be met without adding additional alloy welding materials. Compared with Q355B and other low-alloy high-strength steels, Q235B has simpler welding process and lower welding cost, which is especially suitable for mass production, and can effectively improve the production efficiency and reduce the production cost of LSAW steel pipes, which is one of the important reasons for the outstanding cost performance of Q235B LSAW steel pipes.

Secondly, the mechanical properties of Q235B material are balanced, which is suitable for the requirements of medium and low pressure working conditions. For most industrial and infrastructure projects, the working conditions of pipeline transportation are mostly medium and low pressure (the pressure range is 6~14MPa), and it is unnecessary to use high-strength low-alloy steel or stainless steel, so the mechanical properties of Q235B material can fully meet the demand. According to national standards, the yield strength of Q235B material is ≥235MPa, the tensile strength is 370~500MPa, the elongation at break is ≥26%, and the impact energy at room temperature at 20℃ is ≥ 27 J. Q235b material can withstand the scouring of medium and low pressure fluid, the load of soil and the impact of environment, and has good plasticity and toughness. It is not easy to brittle fracture in various laying environments such as underground and open air, thus ensuring the long-term stable operation of pipelines. For example, in people's livelihood projects such as urban water supply and drainage, central heating, farmland irrigation, etc., the conveying medium is mostly water and hot water, and the pressure is low. The mechanical properties of Q235B material can fully meet the demand, and it is unnecessary to use Q355B material with higher strength, which can greatly reduce the cost of raw materials.