LSAW straight seam steel industry trend of the next six months
ERW steel pipe (ERW straight pipe joints) "is a high-frequency straight seam resistance welding pipe, English Electric Resistance Welding, abbreviation referred to as ERW, used to transport oil, natural gas, gasoline and liquid objects meet the high and low voltage requirements, is currently in the world delivery on the pipe sector accounts for a pivotal position. 1, pipe referring to the regular "submerged arc welding of steel," electrical engineering with "SC" indicates, can be used for water pipe also can be used for gas conduit, relatively thick. 2, line pipe is wire tube, relatively thin, with a "T" indicates, can only do the stringing works. 3, ERW pipe is "a high-frequency electric resistance welded steel pipe", and not the same as an ordinary pipe welding process, the weld is melted by the body from the base metal strip, good mechanical strength than the average pipe. ERW represents resistance welding, resistance welding with high efficiency, low cost, saving materials, ease of automation and other characteristics, it is widely used in aviation, aerospace, energy, electronics, automobiles, light industry and other industrial sectors, it is an important process of welding one. ERW steel pipe (ERW straight seam steel pipe) and seamless steel pipe ERW biggest difference is that there are welds, which is the key to quality ERW pipe. Modernization of ERW steel pipe production technology and equipment, due to the international arena, especially in the United States for many years of tireless efforts to make the seamless steel pipe ERW have been more satisfactory solution.
Someone ERW steel pipe seamless seamlessly into geometric and physical seamless. Geometric seamless ERW steel pipe inside and outside is to remove glitches. Due to the continuous improvement of the structure and tools within the burr removal system and the improvement of medium and large diameter steel pipe burr removal of existing better treatment. Burr can be controlled within about -0.2mm ~ O.5mm. Seamless refers to the presence of physical differences between the interior of the weld and base metal microstructure and mechanical properties of the weld area leads to decline, the need to take measures to make it uniform, harmonization. ERW steel pipe high-frequency welding thermal process, resulting in a gradient of temperature distribution near the edge of the tube, and formed a melting zone, semi-molten zone, overheating tissue, normalizing zone, the feature region area is not completely normalizing, tempering zones. Where the overheated zone organization since the welding temperature above 1000 ℃, the austenite grain grown dramatically under cooling conditions can form a hard and brittle coarse crystalline phase, in addition there is a temperature gradient will produce welding stresses. Thus, the formation of the mechanical properties of the weld region is lower than the base material, the physical is through seamless weld local heat treatment process which uses conventional induction heating apparatus is heated to a weld area AC3 (927 ℃), then 60m length, speed in air cooling process 20m / min, and then cooled when needed. Use this method to achieve the purpose of eliminating stress, soften and refine the organization, to improve the overall mechanical properties of the weld heat affected zone. Currently, the world's advanced ERW unit has been widely used this method to weld process, it has obtained good results. Quality ERW pipe welds not only can not argue that, but the weld coefficient of 1, to achieve a matching Weld regional organizations and the base material.
Source:http://www.jnsteelpipe.com/
