High-temperature heat-proof steel component welding repair method for power station

Abstract

The invention discloses a high-temperature heat-proof steel component welding repair method for a power station. The high-temperature heat-proof steel component welding repair method for the power station comprises the following steps: 1) removing a cracking area with a mechanical method before welding, and preparing a groove; 2) clearly removing a crack along the crack development direction, and polishing the groove; 3) adopting an Ni base welding rod with low Cr content, wherein the welding method of the whole process is manual welding rod electric arc welding; and 4) after welding, heating a welding repair position to 300-400DEG C by an oxyacetylene torch, and covering a thermal-insulation cotton for slow cooling. According to the high-temperature heat-proof steel component welding repair method for the power station, which is disclosed by the invention, low Cr and Ni base welding material is adopted for welding repair, the thermal expansion coefficient of repair area deposited metal prepared from the welding material is low and is similar to that of heat-resistant steel, and the stress level of a fusion area can be obviously reduced under the high-temperature service situation. In addition, because the Ni base welding material has the low Cr content, the service life of the repair area can be obviously prolonged.

Description

technical field [0001] The invention relates to a welding repair method for high-temperature heat-resistant steel parts of a power station. Background technique [0002] Heat-resistant steel components in power stations, such as headers, high-profile doors, plugged valves, and cylinders, work in high-temperature and high-pressure environments. have happened. Welding and repairing these parts can avoid the huge economic loss caused by the overall replacement, and has high engineering practical value. However, due to the short repair period and excessive equipment size, post-weld heat treatment is often not possible under field conditions. In these cases, it is difficult to realize the homogeneous heat repair welding process of post-weld tempering heat treatment, so dissimilar welding materials can only be selected, and the local preheated heterogeneous cold welding method is used for welding repair. [0003] At present, Ni-based welding consumables are mainly selected for h...

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Problems solved by technology

[0004] (1) There is a certain difference in the thermal expansion coefficient between the Ni-based welding consumables used for welding repair and the heat-resistant steel, resulting in a high stress level near the fusion zone, and the repaired parts are prone to creep-fatigue interaction under high-temperature service conditions. Causes cracking in the fusion zone, causing early failure

[0005] (2) The deposited metal composition of Ni-based welding consumables currently selected has a high Cr content (mass percentage greater than 13wt.%), which will cause C elements to have a tendency to migrate from the base metal to the weld. During the high-temperature service of the workpiece Causes the formation of coarse-sized precipitates near the coarse-grained zone and fusion zone of heat-resistant steel, resulting in creep holes and cracking

For example, the literature J.D.Parker, G.C.Stratford. Review of factors affecting condition assessment of nickel based transition joints. Science and Technology of Welding and Joining. 1999, 4(1): 29-39 research shows that the welding prepared by Inconel182 nickel-based welding material When the joint is in service at high temperature, a large number of larger carbides are precipitated in the fusion zone, resulting in performance degradation and final cracking

[0006] (3) Due to the impossibility of post-weld heat treatment, the heat-affected zone toughness of the heat-resistant steel welding repair area is low, which increases the cracking tendency of the repair area

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