Research On ARC Welding Progress Of High Yield Strength Steel DL-700 For Power Fan

Power industry is the economic lifeline of a country, it is very impotent for the economy and people’s daily life. Fan is an indispensable important power plant equipment, the high yield strength steel DL-700 is used for high speed blower impeller, its welding technology research has great significance.DL-700 steel is the main research object of this paper. First of all, the weld ability of the same kind of steels are analyzed in details, then the basic mechanics performance of DL-700 steel is tested and analyzed. On this basis, different t8/5 impact on the performance of the welded joint studied. On the basis of the impact, welding procedure qualification related production is carried out. For the viewpoint of safe operation, according to the wear characteristics of the power station fan, selecte and use two kinds of typical wear-resisting welding materials and two kinds of transition welding materials, in order to stop the wear-resisting layer’s cracks extending to the parent metal. Test results demonstrated:DL-700 steel plate in different rolling direction performed no differences on the tensile strength, yield strength and elongation. Welded joints of DL-700 steel’s mechanical properties affected by the change of t8/5, through the analysis of test data, this paper draped a t8/5 reasonable range from 7.1s to 25.5s, tallies with Germany ThyssenKrupp and SEW-088. DL-700 steels’welding procedure qualification all qualified, expected 2 welding materials with low strength, it covers all welding method, material, position and work piece thickness and possible welding of dissimilar steel, can be used in practical production. Weld wear-resisting material on the surface should be choose for DL-700 steel, no matter have or not have surfacing welding cracks. Because transition layer can prevent the propagation of the crack, so transition welding material for fan has important significance to the safe operation of power plant.Finally, according to the test results and production experience of DL-700 steel fan impeller, welding procedures of DL-700 steel are summarized.