1000MPa-grade hydroelectric high-strength steel pulse welding method

Abstract

The invention relates to a 1000MPa-grade hydroelectric high-strength steel pulse welding method, which mainly comprises the following steps of: processing a butt joint groove which is an asymmetric X-shaped groove, the angle of an overflowing surface groove is 40 degrees, the angle of an outer surface groove is 50 degrees, timely cleaning and polishing a surface hardening layer and oxides after the groove is processed until metal luster is leaked, preheating a welding seam before welding, and welding the welding seam after welding. Welding seam preheating is carried out in an electric heating mode, the preheating temperature is controlled to be not lower than 130 DEG C, the interlayer temperature is controlled to be 140-170 DEG C, the post-heating temperature is 230-280 DEG C * 2-4 h, the ratio of mixed gas is 85% of Ar to 15% of CO2, a pulse welding machine is used for carrying out pulsed arc transition welding, and welding is carried out after welding. Important technical support is provided for comprehensive autonomy of manufacturing of high-water-head and large-capacity impact type and pumped storage unit complete equipment, and a solid foundation is laid for subsequent manufacturing of key core pressure-bearing components such as 1000 MPa-level high-strength steel water diversion pressure pipelines and steel branch pipes. The welding process is successfully applied to Zhejiang rooftop pumped storage steel branch pipe projects, and practices prove that the process is feasible and can be popularized and applied.

Description

Technical Field

[0001] The invention belongs to the technical field of pumped storage power station pressure pipeline welding, in particular to a 1000MPa grade hydropower high-strength steel pulse arc transition welding method. Background Art

[0002] With the development of clean energy in the country, the steady promotion of green and low-carbon energy, large-scale pumped storage power stations in China have sprung up like mushrooms after a rain, with increasing capacity and head. In this way, it is necessary to provide pressure pipes with higher pressure and larger flow to meet the safe and stable operation of pumped storage power stations and realize their functions. The main driving force of high-strength steel application is the power station's goal of achieving high head and large capacity. The welding difficulty of 1000MPa-grade hydropower high-strength steel is particularly large, and the product welding process is still blank in China. The process technology parameter window is very narrow, which is mainly manifested in the cold and hot crack sensitivity of 1000MPa-grade steel plate welding, the influence of welding line energy on the performance of 1000MPa-grade steel plate joints, high-purity welding joint process assurance, high-strength and tough welding joint organization and performance assurance. By adopting steel plates with higher strength grades and smaller wall thicknesses, reducing the weight and welding amount of steel pipes, and thus reducing construction time and cost, it can produce huge benefits in terms of material reduction and cost reduction. Summary of the invention

[0003] The purpose of the present invention is to provide a 1000MPa grade hydropower high-strength steel pulse welding method, which effectively guarantees the performance quality of the welded joint and fills the domestic 1000MPa grade hydropower high-strength steel welding process gap.

[0004] The invention has been improved through repeated exchanges and discussions with technicians and welding personnel, multiple welding process assessment tests and research, and practice. Finally, a domestic 1000MPa grade hydropower high-strength steel pulse welding method was successfully developed by mastering the 1000MPa grade high-strength steel welding technology.

[0005] The technical solution of the present invention is: The specific steps of the 1000MPa grade hydropower high-strength steel pulse welding method are as follows: Step 1: Processing of the butt groove, the groove is an asymmetric X-shaped groove, the groove is larger outside and smaller inside, the groove angle of the inner flow surface is 40°, and the groove angle of the outer surface is 50°. After the groove is processed, the surface hardened layer and oxides are cleaned and polished in time until the metallic luster is exposed; Step 2: Preheat the weld before welding. The weld preheating is carried out by electric heating. The minimum preheating temperature is controlled to be no less than 130℃, the interlayer temperature is controlled between 140℃ and 170℃, the post-heating temperature is 230℃ to 280℃, the post-heating time is 2h-4h, and the mixed gas ratio is 85%Ar:15%CO2.

[0006] Step 3: Welding: Use a manual gas shielded welding pulse welder to perform pulse arc transition welding (the welding process parameters must strictly follow the welding process instructions confirmed by the welding process assessment).

[0007] Furthermore, the outer groove angle described in step 1 is 50° with a deviation of -1° to +3°, and the inner groove angle is 40° with a deviation of -1° to +3°.

[0008] Furthermore, the asymmetric X-shaped groove described in step 1 has a blunt edge of 2 mm.

[0009] Furthermore, the pulse welding method uses an OTC P500L welding equipment with a pulse function, the flat welding current is 140A to 160A, the welding voltage is 20V to 26V, and the welding speed is 150 to 320mm / min, the horizontal welding current is 150A to 240A, the welding voltage is 22V to 28V, and the welding speed is 200 to 320mm / min, the vertical welding current is 100A to 150A, the welding voltage is 18V to 22V, and the welding speed is 100 to 240mm / min, and the overhead welding current is 100A to 130A, the welding voltage is 18V to 22V, and the welding speed is 100 to 240mm / min.

[0010] The domestic 1000MPa-grade hydropower high-strength steel pulse welding method of the present invention controls the groove form, welding process parameters, welding equipment, gas ratio, preheating temperature, post-heating temperature, etc., and adopts OTC P500L welding equipment with pulse function for welding. The welding quality is verified by experiments and the product welding is reliable, which fills the domestic 1000MPa-grade hydropower high-strength steel welding process technology gap. By mastering the 1000MPa-grade high-strength steel welding technology, it provides important technical support for the comprehensive independent manufacturing of high-head, large-capacity impact and pumped-storage unit equipment, and lays a solid foundation for the subsequent manufacturing of key core pressure-bearing components such as 1000MPa-grade high-strength steel water diversion pressure pipelines and steel bifurcated pipes. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 It is a schematic diagram of the groove structure of the pulse welding method for 1000MPa grade hydropower high-strength steel of the present invention. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment.It will be appreciated by those skilled in the art that the following examples are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.In the embodiment, if specific techniques or conditions are not indicated, they are carried out according to the techniques or conditions described in the literature in this area or according to the product specification.If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be obtained by purchase.

[0013] At the same time, the terms such as "inside", "outside", "deviation", "large", "small", etc. cited in this specification are only for the convenience of description to be clearer, and are not used to limit the scope of implementation of the present invention. Changes or adjustments in their relative relationships should also be regarded as the scope of implementation of the present invention without substantially changing the technical content. Example

[0014] A 1000MPa grade hydropower high-strength steel pulse welding method: Step 1: Processing of the butt groove of 1000MPa grade hydropower high-strength steel weld. The groove is an asymmetric X-shaped groove. The groove angle of the flow surface is 40°, the deviation is -1°~+3°, the groove angle of the outer surface is 50°, the deviation is -1°~+3°, and the blunt edge is 2mm. For details of the groove diagram, see Figure 1 After groove processing, the surface hardened layer and oxides shall be cleaned and polished in time until the metallic luster is revealed. No defects are allowed on the groove surface. Step 2: Preheat the weld before welding. The weld preheating is carried out by electric heating. The minimum preheating temperature is controlled to be no less than 130℃, the interlayer temperature is controlled between 140℃ and 170℃, the post-heating temperature is 230℃ to 280℃, the post-heating time is 2h-4h, and the mixed gas ratio is 85%Ar:15%CO2; Step 3: Use a manual gas shielded welding pulse welder to perform pulse arc transition welding. The welding process parameters must strictly follow the welding process instructions confirmed by the welding process assessment.

[0015] Preferably, the welding equipment is OTC P500L welding equipment with pulse function.

[0016] Priority, flat welding current is 140A ~ 160A, welding voltage is 20V ~ 26V, welding speed is 150 ~ 320mm / min, horizontal welding current is 150A ~ 240A, welding voltage is 22V ~ 28V, welding speed is 200 ~ 320mm / min, vertical welding current is 100A ~ 150A, welding voltage is 18V ~ 22V, welding speed is 100 ~ 240mm / min, overhead welding current is 100A ~ 130A, welding voltage is 18V ~ 22V, welding speed is 100 ~ 240mm / min, as shown in the following table:

[0017] In summary, the domestic 1000MPa-grade hydropower high-strength steel pulse welding method of the present invention controls the groove form, welding process parameters, welding equipment, gas ratio, preheating temperature, post-heating temperature, etc., and adopts OTC P500L welding equipment with pulse function for welding. The welding quality is verified by experiments and the product welding is reliable, which fills the gap in domestic 1000MPa-grade hydropower high-strength steel welding process technology. By mastering the 1000MPa-grade high-strength steel welding technology, it provides important technical support for the comprehensive independence of high-head, large-capacity impact and pumped storage unit equipment manufacturing, and lays a solid foundation for the subsequent 1000MPa-grade high-strength steel water diversion pressure pipelines, steel bifurcated pipes and other key core pressure-bearing components. The welding process has been successfully applied in the Zhejiang Tiantai pumped storage steel bifurcated pipe project, and practice has proved that the process is feasible and can be promoted and applied.

[0018] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A 1000MPa grade hydropower high-strength steel pulse welding method, characterized in that: The steps include: Step 1: Processing of the butt groove, the groove is an asymmetric X-shaped groove, the groove is larger outside and smaller inside, the groove angle of the inner flow surface is 40°, and the groove angle of the outer surface is 50°. After the groove is processed, the surface hardened layer and oxides are cleaned and polished in time until the metallic luster is exposed; Step 2: Preheat the weld before welding. The weld preheating is carried out by electric heating. The minimum preheating temperature is controlled to be no less than 130℃, the interlayer temperature is controlled between 140℃ and 170℃, the post-heating temperature is 230℃ to 280℃, the post-heating time is 2h-4h, and the mixed gas ratio is 85%Ar:15%CO2; Step 3: Welding: Use a manual gas shielded welding pulse welder to perform pulse arc transition welding.

2. The 1000MPa grade hydropower high-strength steel pulse welding method according to claim 1, characterized in that: The outer groove angle described in step 1 is 50° with a deviation of -1° to +3°, and the inner groove angle is 40° with a deviation of -1° to +3°.

3. The 1000MPa grade hydropower high-strength steel pulse welding method according to claim 1, characterized in that: The asymmetric X-shaped groove described in step 1 has a blunt edge of 2 mm.

4. The 1000MPa grade hydropower high-strength steel pulse welding method according to claim 1, characterized in that: The pulse welding method uses OTC P500L welding equipment with a pulse function.

5. The 1000MPa grade hydropower high-strength steel pulse welding method according to claim 1, characterized in that: The flat welding current is 140A~160A, the welding voltage is 20V~26V, the welding speed is 150~320mm / min, the horizontal welding current is 150A~240A, the welding voltage is 22V~28V, the welding speed is 200~320mm / min, the vertical welding current is 100A~150A, the welding voltage is 18V~22V, the welding speed is 100~240mm / min, the overhead welding current is 100A~130A, the welding voltage is 18V~22V, and the welding speed is 100~240mm / min.

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