Defect repairing method of investment precision casting for liquid rocket engine
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A defect repair, liquid rocket technology, applied in welding media, arc welding equipment, welding/cutting media/materials, etc., can solve problems such as uneven distribution of residual stress, improve delivery qualification rate, avoid grain growth, The effect of reducing production costs
Active Publication Date: 2020-12-11
XIAN SPACE ENGINE CO LTD
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[0011] In order to overcome the deficiencies in the prior art, the present inventor has carried out determined research, and provides a method for repairing defects of ZG03Cr13Ni5Co9Mo5 and ZG06Cr14Ni7Mo investment castings for liquid rocket engines. The special welding wire for ZG06Cr14Ni7Mo castings is based on the grade I weld of QJ1842-95 "Technical Conditions for Fusion Welding of Structural Steel and Stainless Steel" as the evaluation standard, and a welding process database based on the initial thickness of the repair welding part of the casting is established to ensure that the welding strength meets the design requirements. , and proposed a special post-weld heat treatment system for ZG03Cr13Ni5Co9Mo5 and ZG06Cr14Ni7Mo castings, which solved the problem of uneven distribution of internal organization and residual stress, thereby completing the present invention
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Embodiment 1
[0066] In this example, the investment casting is the primary pump impeller of a certain type of fuel pump, the material is ZG06Cr14Ni7Mo, and the structure is as follows figure 2 and image 3 shown.
[0067] (1) Defect location.
[0068] The internal quality inspection method of the casting is X-ray inspection, the surface quality inspection method is fluorescent inspection, and the inspection level in the design drawing is Class B, and the allowable defects comply with the provisions in Table 2 and Table 3. If the above two inspection methods find defects beyond those specified in Table 2 and Table 3, the results shall be displayed on the X-ray film and the surface, and the position and size of the defects shall be marked on the casting.
[0069] Table 2 X-ray Inspection Standards for Castings
[0070]
[0071] Table 3 Fluorescent Inspection Standards for Castings
[0072]
[0073]
[0074] (2) Defect exclusion. Determine the size and location of the defect ac...
Embodiment 2
[0085] In this embodiment, the investment casting is a certain type of turbine oxygen pump centrifugal wheel, the material is ZG03Cr13Ni5Co9Mo5, and the structure is as follows Figure 8 and Figure 9 As shown, the primary impeller of the fuel pump has the same structure as the centrifugal impeller of the turbo oxygen pump in Embodiment 1 except that the blades rotate in the opposite direction.
[0086] The defect repair method is consistent with that in Embodiment 1, the only difference is:
[0087] The welding wire is wire-cut from the master alloy bar for casting, and the chemical composition should meet the requirements of the casting master alloy GJB7961. The specific chemical composition: 13.0% to 15.0% of Cr element, 6.0% to 8.5% of Ni element, 0.5% to 1.0% % Mo element, the rest is Fe element. The initial thickness of the repair welding part in this implementation is 5mm, and the welding process parameters are selected: the welding current A is 170A, the number of we...
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Abstract
The invention provides a defect repairing method of an investment precision casting for a liquid rocket engine. The defect repairing method comprises the following steps of: positioning defects; removing the defects; machining a groove; treating a repair welding part; performing welding; and performing postweld treatment. According to the defect repairing method, welding wires for ZG03Cr13Ni5Co9Mo5 and ZG06Cr14Ni7Mo castings are defined, and a welding process database based on the initial thickness of repair welding parts of the castings and a postweld heat treatment system are established; acorresponding repair process is adopted; the tensile strength of an obtained ZG03Cr13Ni5Co9Mo5 weld joint at a room temperature is greater than 1070 MPa (the matrix strength is not lower than 1180 Mpa), the rate of elongation is not lower than 15%, and the low-temperature impact toughness at the temperature of minus 196 DEG C is not lower than 39 J; the tensile strength of a ZG06Cr14Ni7Mo weld joint at a room temperature is greater than 900 MPa (the matrix strength is not lower than 980 Mpa), the rate of elongation is not lower than 12%, and the low-temperature impact toughness at the temperature of minus196 DEG C is not lower than 31 J; the internal quality and the surface quality of the weld joints are qualified; and the weld joints meet the I-grade weld joint standard of QJ1842-95 structural steel and stainless steel fusion welding technical conditions and the use requirements of spaceflight products.
Description
technical field [0001] The invention belongs to the technical field of investment precision casting, in particular to a method for repairing defects of ZG03Cr13Ni5Co9Mo5 and ZG06Cr14Ni7Mo investment precision castings for liquid rocket engines. Background technique [0002] Investment casting has the characteristics of high dimensional accuracy, good surface quality, and unrestricted structure, and is widely used in the production of liquid rocket engine castings. [0003] In order to meet the development needs of a new generation of high-pressure supplementary combustion liquid rocket engines, such as high chamber pressure, high speed, high thrust, and ultra-low temperature, ZG03Cr13Ni5Co9Mo5 and ZG06Cr14Ni7Mo martensitic stainless steel for investment casting have been developed, both of which are carbon-free (or ultra-low carbon) ) Martensite-based ultra-high-strength steel, through low-carbon martensitic phase transformation and aging precipitation of intermetallic compo...
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