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Method for repairing defects of pipe orifice of high-alloy hollow valve shell casting

A technology for hollow valves and defects, which is applied in the repair field of nozzle defects of high-alloy hollow valve casing castings, to achieve the effect of improving repair quality, reducing internal stress and reducing defects

Inactive Publication Date: 2015-03-25
KOCEL STEEL
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Problems solved by technology

[0005] The purpose of the present invention is to overcome the defects of the prior art, to provide a unique method, which can minimize the defects, effectively reduce the internal stress caused by uneven preheating, reduce the defects caused by welding, and reduce the cost. A method for repairing nozzle defects of high-alloy hollow valve casing castings

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Embodiment Construction

[0017] A method for repairing nozzle defects of high-alloy hollow valve casing castings, which is characterized in that: the method first carries out defect gouging from the inner side, and then removes the defects from the outer side, and then uses heating equipment to pre-heat all the upper and lower parts of the nozzle. Heat, then use the welding principle from the inside to the outside and the multi-layer and multi-pass welding sequence, the welding method with the swing width of the electrode ≤ 20mm for welding, and finally perform post-weld heat treatment.

[0018] The specific method is as follows:

[0019] 1) Excavation of defects a. In the range of 50mm from the inside of the nozzle, the defect gouging is carried out from the inside, and the rest are excavated from the outside;

[0020] b. Carbon rods with a diameter of 13mm are used for gouging. For larger defects, carbon rods with a diameter of 13mm are used for gouging at the bottom of the defect, and carbon rods ...

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Abstract

The invention relates to a method for repairing crank defects of high-alloy steel castings, in particular to a method for repairing defects of a pipe orifice of a high-alloy hollow valve shell casting pipe orifice. The method comprises the steps that firstly, defects are gouged and removed from the inner side of the pipe orifice, and then the remaining defects are removed from the outer side of the pipe orifice; secondly, a heating device is used for preheating both the upper portion and the lower portion of the pipe orifice, and then welding is conducted according to the inside-to-outside welding principle in a multilayer multipass welding sequence through the welding method that the swing width of a welding rod is smaller than or equal to 20 mm; finally, postweld heat treatment is conducted. The method is unique, the defects can be minimized, internal stress caused by uneven preheating is effectively reduced, the defects caused by welding are reduced, and cost is lowered.

Description

technical field [0001] The invention relates to a method for repairing crack defects of high-alloy steel castings, in particular to a method for repairing nozzle defects of high-alloy hollow valve casing castings. Background technique [0002] High-alloy hollow valve casing castings are one of the core products of steam turbines. The wall thickness difference of the nozzle of the casting reaches 250mm, the inner diameter of the nozzle is 100mm, and the distance between the outer end surface of the nozzle and the inner cavity is 400mm. Due to factors such as large wall thickness variation, small diameter and deep depth, immature production process, and unstable material structure, the nozzle of this product has different degrees of visible crack defects at the nozzle after the heat treatment of the casting quality. In actual production, once a crack defect occurs at the nozzle of the casting, the depth varies and runs through the entire pipe. The traditional repair process f...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23P6/00
CPCB23P6/04
Inventor 陈得润李成志曹鹏胡进林李文辉雷永红张宏凯
Owner KOCEL STEEL
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