Q420 tower transmission line tower materials processing materials

Abstract: This paper is for the design of the existing transmission line towers to introduce new material type Q420, Q420 material from the physical and chemical properties of materials in terms of the impact of the introduction of new processing and testing aspects Tower, indicating that processing and welding should be noted matters to ensure the quality of the products to be discussed.

Keywords: Tower; Q420; processing
Abstract: This article is mainly aims in the existing transmission line iron tower design to introduce new material quality type Q420, to introduces the iron tower processing which and the examination aspect from Q420 material quality's physics and the chemical properties aspect the new material quality affects explained that processes the item which and welds should pay attention to guarantee the product the quality has carried on the elaboration.

Keywords:: iron tower; Q420; processing

With the rapid development of industry, as the power output of basic industries play a particularly important role in early 2008, our big ice storm occurred in the south for a higher power transmission line tower requirements, how to improve the Eiffel Tower in the extreme the ability of the environment, from the perspective of design and processing to improve risk prevention Tower urgent and necessary. from the aspect of economy and efficiency start to improve the performance of the material to resist foreign natural disasters.

1 Q420 physical and chemical properties of materials
2 Q420 incoming material inspection and welding materials requirements
Q420 high-strength steel into the plant inspection items include the appearance of steel quality, size, tolerance, mechanical properties and chemical element analysis, the appearance of quality steel products shall meet the relevant standards and design requirements, there should meet the following requirements: When steel surface corrosion, pitting or scratches and other defects, its depth not greater than the thickness of the steel allows the negative deviation of 1 / 2; steel side edge or the fracture should not be layered, mixed and other defects. welding material into the plant should provide a certificate of product quality (including the cladding metal chemical composition, mechanical properties guaranteed, the recommended welding parameters, etc.). Q420 high-strength steel, welded steel and other low-level, the better to use the low level of intensity and the side of steel matching welding material. rod, flux should be in accordance with the instructions in the use of the request before the drying, repeat the drying not more than twice. damp the electrode should not be used. wire should be clean before use rust, dirt, oil.

Links to Research Papers Download http://www.hi138.com 3 Q420 material machining requirements
Q420 material from the physical properties of the chemical properties and start, Q420 material angle and the poor mechanical properties of sheet strength, although high, but the toughness, ductility is low. Welding, the tendency of large brittle. Hot and cold workability is still good, but the gap greater sensitivity. It is for this reason, from the design specifications and requirements of the State Grid Corporation of Q420 in all material set forth requirements for machining, materials processing involving Q420 drilling process must be used, that is, through hole to weaken the notch sensitivity, to improve the mechanical properties of materials used, so the required angle of Q420 material cutting through the band saw to completion. all use the site need to punch holes.

4 heat and thermal distortion correction process
Thermal correction should be neutral flame heating. Heat correct position before the heat should be identified and corrective steps. Workpiece after the first heat did not meet the required correction, does not allow repeated heating in the original location. Heating temperature at 200 �� ~ 300 �� range non-hammering and bending. heat correct spots commonly used heating method for heating or linear. plus hot spots diameter determined according to the thickness of sheet metal, typically 10 mm ~ 30 mm, plus hot deformation determined based on the spacing, should normally greater than 50 mm. linear heating plus hot plate width should be 0.5 to 2 times the thickness, plus the distance between the hot parts of the roughness, as determined in general should be larger than 50 mm. heating should be uniform when the flame moves. hot corrected when the heating temperature should not exceed 900 ��. Thermal correction of the work piece forced cooling is strictly prohibited. at low temperature (0 �� or less) thermal correction, the heating area measures should be taken to slow cooling. hot deformation processing techniques before the need to process documents in accordance with drawings confirm the workpiece to develop technology program. hot deformation processing should be used for special equipment and tooling. on the plate, when the curved line pattern perpendicular to the direction and the rolling process, the minimum thermal deformation radius of curvature of 1.5 times the thickness, when the bending corrugated line parallel to the direction and the minimum curvature radius of 2 times thickness; on the angle, the processing behind the thinnest thickness of not less than 75% of the original thickness; of steel, the processing time of the minimum curvature radius of 2 times the pipe diameter, and to take appropriate measures to prevent loss of circular steel pipe. should be used for heating furnace, coal stove or oil furnace and other equipment, not using oxygen gas flame heating.

5 welding process
Q420 high-strength steel welding welders, technical management, quality control personnel, should be subject to special Q420 high-strength steel welding technology assessment, to obtain the appropriate qualification certificate is required for welding, technology management, and quality inspection; nondestructive testing personnel, subject to professional examination bodies authorized by the state passing the examination, the corresponding certificates should be in the validity and authority by passing the examination in the project and review the work of non-destructive testing welds. welding equipment and auxiliary equipment shall meet the requirements of welding parameters, before welding the first welding procedure qualification, procedure qualification testing by the relevant national technical quality supervision department with certified qualification test units; welding, the operation area of ​​the ambient temperature shall not be less than 5 ��, relative humidity of not more than 90%, or Preheat measures should be taken weldment. groove preparation methods should be mechanical processing. welding parts in the group should be thoroughly removed before welding on site and the surrounding 10 mm ~ 15 mm range of oxide, oil, rust and other debris, until the exposed metal luster. positioning welding materials used in welding, welding technology should be officially welding materials, processes the same. locate the weld seam thickness of not more than the design thickness of 2 / 3, positioning weld length appropriate for the 30 mm ~ 50 mm, interval of not more than 600 mm. positioning welding, is strictly prohibited outside of the base metal in the weld on the arc, arc extinction when the pit filled.

Quality inspection requirements 6
Quality inspectors should first examine the factory material inspection certificate Q420, Q420 to ensure the physical and chemical properties of materials to meet the requirements; further after the re-examination of raw materials (including appearance and physical and chemical properties), only be carried out to meet the requirements of all these put into production use. aspects of the various processes of production technology to strictly abide by the rules and design requirements for testing, to ensure that every link in the control of the scale. heat correct on steel surfaces, concave or should not have significant damage, scratch depth not greater than 0.5 mm, and should not be greater than the thickness of the steel allows negative deviation of 1 / 2. heat correct defects in the workpiece surface cracks are not allowed. steel heat corrected size of permitted deviation, shall comply with relevant regulations. by Number of random 10% correction, and should not be less than 3, inspection and test methods for the observation of actual checks. sampling artifacts, if any failed parts, sampling should be doubled. If there are still parts failed double sampling artifacts, the response The remaining parts of the full inspection.

7 Conclusion
This paper mainly introduces the transmission line towers in the introduction of new material Q420, from inspection of raw materials to production and processing of the technological requirements of the various processes and the actual practices, the face of new technical requirements on the tower and processing enterprises proposed a new subject. requires only processing enterprises Tower strict compliance with national standards and technical requirements in order to ensure processing quality and safety performance tower.

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