Study On Optimized For Welding Process Of The Crack In High-pressured Cylinder Of Steam Turbine

The steam turbine is one kind take the steam as a working substance, and transforms the steam heat energy into the mechanical merit revolving machinery. Turbine's metal part prime task under 500℃. The stress situation is extremely complex. The high temperature high pressure's steamship unit, changes the need which for the adaptation load and overhauls, opens frequently frequently stops and fluctuates the load, the withstanding alternate stresses, the steam turbine structure is complex, thickness is extremely non-uniform, the stress situation is extremely complex, the change has the fatigue failure, produces the crack, the welding repair difficulty is enormous.This research content includes: The steam turbine high pressure cylinder uses the material quality basically belongs to Cr-Mo is the pearlyte high-temperature steel, moreover in the power plant steam turbine is high to the steel welding performance request, its Cast structure and the steel pipe structure property is almost the same. Through carries on the classification comparison to the steam turbine high pressure cylinder patching's each kind of welding process, selects with the steam turbine high pressure cylinder's ingredient, the performance close 12Cr1MoVG pearlyte high-temperature steel, through the R317 welding rod arc heating patching, a132 welding rod electric arc neterogeny half thermit welding and the nickel base welding rod electric arc neterogeny metal cold welding and so on has the representative three technique, according to the welding process method which draws up beforehand carries on the welding process evaluation, the contrast research, then carries on the high temperature thermal simulation to try difficultly, and conducts the welding process optimization research, discovers the quite good welding process, uses in instructing the actual production.In order to inspect the steam turbine high pressure cylinder patching spot the operational performance, divided half quantity the above three kind of attachments to carry on the high temperature aging treatment of metal, examined its mechanical properties, inspected the long-term operational performance which the welding met. The high temperature aging treatment of metal is carries on for 50 hours, 770℃the constant temperature heating, is comes according to the Lassen-miller parameter inferential reasoning, it is equal in the cylinder body in 540℃under moves for 100,000 hours. After the craft evaluation's test content mainly includes welds, under the shape and the high temperature effectiveness two kind of stretches, the surface is curved, the back is curved, impact, degree of hardness and metallographic test, and from contrast factor analyses and so on technology capability, scene feasibility, mechanical properties.The results show that three types of welding consumables in the welding of the welded joints (or after welding to stress annealing state) under the welding procedure qualification test results are in line with the relevant eligibility criteria, but in aging heat treatment, the three types of joints and the performance of both of which occurred in varying degrees of transformation, especially the use of semi-hot rod A132 welding joints bending test (including side bends and back bends) in parts of fusion line cracks caused by procedure qualification test failure.Using R317 thermal welding electrode law toughness poor joints, using A132 electrode semi-hot welding fusion line near the first organizations to use and performance in high-temperature process is less stable. At the same time, the existence of these two programs are poor construction, welding deformation shortcomings such as difficult to control, so are not suitable for the repair welding cylinder high-pressure steam turbine. The use of nickel-based electrode cold Law of the excellent performance of the joints, and has good heat stability, and its simple process, welding deformation of small, should be used as high-pressure steam turbine of choice for catch-cylinder welding technology program.For high temperature Weldment use, in addition to conventional welding procedure qualification tests, the proposed supplementary adequate performance of high-temperature aging treatment and testing in order to assess the performance of heat-stable joints.