ERW straight welded pipe weld shape

High-frequency welding pipe ERW process is the use of high frequency current generated by the skin effect of the principle of the edge of the hot rolled coil is heated to a molten state, and then by mechanical extrusion welding. Indeed through this process to produce welded steel pipe weld fusion center will have a white line on both sides of the fusion line will produce heat affected zone extending from the middle to the surface of the metal flow lines. During the welding process, the metal tube experienced a cold, hot, then cold thermal cycling process, therefore, the physical and chemical properties of the base material, grain size, non-metallic inclusions, forming and welding conditions and heat treatment process, and this will the weld toughness properties, especially impact punch. In the pipe production process, the impact toughness by selecting coil to ensure the performance of welded steel base metal, combined with adjustment of the welding process to ensure the best possible control and reduce defects, guarantees a high performance of the weld.

Welding quality of weld seam by the appearance of the weld morphology, surface conditions and the mechanical properties of the weld testing and metallographic analysis to judge. In the production process, the curved shape and the surface condition of the seam welding process can be adjusted to provide a reference. Mechanical properties testing generally in accordance with the standard requirements or customer specific requirements. Appearing in a variety of pipe production quality defects are caused by many factors, but mainly due to the weld quality problems inside and outside edge of the plate and extrusion temperature and the heating temperature does not match the result. Board outside edge temperature can not exceed the range of inconsistency, otherwise it will have serious quality problems. One of the more typical problem is the two extremes burnt and cold welding. Burnt is to ensure that all of the inner and outer "penetration", resulting in high temperature side of the "burnt." When removing burrs, the oxides can be found and impurities remain in the right side, the naked eye can see the formation of cracks or holes are not welded. By flattening slightly lighter degree can check out. Or to limit the scope of the outside temperature exceeds a certain cause other side appeared cold welding. When the temperature is not completely outside the above range, the quality of the welding must be checked to determine. Heating of the slab edge is consistent by observing the inner and outer weld burrs or protrusions are the same size can be. Generally indicates the outer edge of the outer coarse protrusions on the inside edge of the heating intensity, whereas the inner edge of the high temperature. Between a heating temperature of the pressing amount is appropriate bonding surface will ultimately affect the strength of the weld and weld appearance. Typically the welding process, the following occurs: When asked appearance quality, often appear soldering temperature is too low; when stressed weld strength, it usually occurs soldering temperature is too high; Or proper welding temperature, extrusion volume control improper. Typically, the amount of compression can have a proper range, when the squeeze is large, due to lower heating temperature; when pressing volume is small, appropriately increasing the heating temperature, which ensures that the weld strength and weld shape to achieve better combined effect.