Electrode selection and use of a direct impact on the appropriateness of the chemical composition and weld performance, large-diameter seamless steel pipe welding is a very important preparation for a part. Select the appropriate electrode, a number of factors to be taken into account, and sometimes need to do experimental verification, can be finalized. Need to consider the following aspects of the use of performance requirements of the weld metal, electrode shape, rigidity and weld position, weld metal crack resistance, operating processes, equipment and construction conditions, economic rationality.
Large-diameter seamless steel pipe heat treatment of large forgings of large forgings mainly by direct forging into ingots, and therefore must be considered in the heat treatment smelting, ingot casting, forging and other processes of the internal quality of the casting, as long as the factors are: non-uniform chemical composition the presence of defects in a variety of smelting; coarse grains, and very uneven; more gas and impurity materials; large forging and heat treatment stress stress. After the heat treatment of large forgings forging white point and purpose is to prevent hydrogen embrittlement, to improve the internal organization of forging, forging to eliminate stress, reduce the hardness to improve cutting performance, to obtain good mechanical properties after heat treatment or for the good organization and preparation.
Large-diameter seamless steel forging on part of the casting of large forgings. Large-diameter seamless steel pipe with welded main differences are the different molding process. Ordinary steel, such as water pipes, generally through the flat plate by welding after bending up, you can find a seam in the above; is generally thicker in diameter spiral weld. The seamless steel pipe is generally the molten steel through the annular slit of the backlog by stretching out before treatment processes such as molding, so that no seam. In performance, especially on the bearing capacity has greatly improved as compared with ordinary steel, it is often used for high voltage devices. Such as hydraulic equipment, piping connections. The ordinary steel pipe weld area is its weak link, weld quality is also affecting the overall performance of the main factors. People who lived in the north generally have had water pipes or heating pipe burst in the winter experience of being frozen, burst welds are generally the place. Seamless pipe is not. Seamless steel pipe production process is mainly done by the tension-reducing, tension-reducing process is hollow mandrel base metal without the continuous rolling process. In ensuring the quality of the mother under the premise of pipe welding, pipe tension reducing the overall process is to pipe heated to 950 degrees Celsius, and then stretch reducing mill (tension reducing mill there 24 times) rolling into a variety of outer diameter pipe with wall thickness of the finished product, produced using this process hot-rolled steel pipe with an ordinary essential difference between the high-frequency furnace heating through the weld and the parent of the microstructure and mechanical properties can be achieved exactly the same addition, large-diameter seamless steel pipe more than pass through the stretch reducing mill makes steel rolling and automatic control of dimensional accuracy (especially in tube roundness and wall thickness accuracy) than similar seamless.
Countries in the world production of fluid pipes, boiler tubes have been widely used in the process of seamless pipe, with the development of society, domestic hot-rolled seamless pipe instead of the situation has been gradually formed. Seamless steel pipe with large diameter difference can be several ways from the first pipe is cut to length in general, and are generally 6 meters, nine meters or 12 meters. Seamless steel pipe cut to length is very small, because the cut-factory increase very much. The second head from the pipe cross-sectional view, if there is rust, then wipe clean, look carefully will find the welding zone. If you look at the third acid, then the most obvious. After coating the coating material in the pre-quality steel in the indirect effects of the coating compete with power off. On the appearance of large diameter pre-coated steel pipe volume should reach GB/T8923 scale in designated Sa2 Level to supply. According to the needs of different coating PVC, polyethylene, epoxy resin and other various properties of plastic coating, good adhesion, corrosion resistance, and can be resistant to acid, alkali and other chemical corrosion, non-toxic, not rust, wear, impact resistance, strong penetration, pipe surface is smooth, does not adhere to any substance that can reduce delivery time of resistance, increase traffic and transportation efficiency, reduce transport pressure loss. Coating solvent, no leakage of material, which does not pollute the transmission medium, in order to ensure fluid purity and health, in the range of -40 ¡æ to +80 ¡æ thermal cycling can be used interchangeably, not aging, not cracking, which can in cold areas such as the use of harsh environments. Degree anchor light pattern to 50¦Ìm-75¦Ìm. Appearance of pre-6h successful within the pipe should be coated, the new super power should be handled after 6h. Large-diameter seamless steel pipe elastic deformation, improper operation of the construction of large diameter steel pipe easy to make a greater vertical deformation as well as instability, seriously affecting the use of functions.