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Perforation status and improvement measures of the immediate failure

2016/7/11      view:

    Perforated top head is one of the most important tools in the production of seamless steel tube. Due to perforation of the plug of the poor working conditions, thus making its use life is not high, analysis from the following aspects, can effectively improve the perforation top life.


    1 The improvement of the material piercing plug


    Currently, domestic production of ordinary carbon steel pipe application more immediate material 3Cr2W8V and 20Cr2Ni4W steel. Before use, plug of hanging film processing; common base alloy plug production of stainless steel pipe, the high temperature oxidation serious and need to continue to carry out high temperature lubricating. Practice show that the new compound plug, namely to 3Cr2W8V steel as the main body, is made into a hollow plug, plug nose and heat resistance surfacing alloy in constitute model compound plug. Better results, in addition to the use of 15Cr2Ni3MoW material instead of 20CrNi3 material, the use of 38CrNiMoV steel instead of 20CrNi3 steel is very good.


    2 improve head structure and cooling conditions


    The plug wall thickness should be reasonable. When the head wall is too thin, the composite strength could not withstand the frequency of stress caused brittle cracking. But too thick, immediate internal water cooling effect will be significantly weakened, which led to the plug surface temperature is too high, sticking steel, eating meat failure. Plug reasonable wall thickness of immediate maximum diameter of 0.18-0.22. In addition, plug nose shape and rolling and the transition section of the concave part of the spray hole, not only to improve the head and working section of the cooling conditions and continuous updating of the oxide film, will be perforated metal at high temperature and plug metal is separated from the heat insulation and lubrication. In addition, to ensure that the cooling water pressure maintained at 1 ~ 1.5MPa above the good cooling effect, can prolong the service life of plug.


    3 the use of rare earth Aluminum Alloy to improve the service life of piercing


    The study shows that adding a small amount of rare earth elements in steel can improve the high temperature strength, plasticity, wear resistance and fatigue life of steel, and improve the oxidation resistance and corrosion resistance of steel. Hai'an wedding the ladle bottom flushing method and adding 0.1% rare earth can significant grain refinement, effectively removal steel gas and the harmful elements P, s, purifying the liquid steel; at the same time, rare earth can also effectively improve the morphology of inclusions in steel, making drill steel performance is better.


    4 Heat treatment


    The heat treatment process to achieve two objectives: 1. To plug the matrix microstructure of granular bainite and martensite. High temperature oxidation treatment surface of the plug to form a dark grey full, smooth and dense oxide film, and has a good adhesion and plug the matrix.


    5 Effect of rolling process on the plug life


    In the rolling process and head shape design should pay attention to improve the rolling speed, reduce the head and pipe contact time. According to the main aspects of the failure of the appropriate adjustment of heat pipe technology parameters. To improve the shape of the inner cooling, appropriately increasing the wall thickness of the rolling zone, plug life better.