JB/T 7029-1993 Technical Specifications for Non-magnetic Guard Ring Forgings for Turbogenerators below 50MW JB/T7029-1993 Standard Download Decompression Password: www.bzxz.net

Mechanical Industry Standard of the People's Republic of China
Technical Conditions for Non-magnetic Guard Ring Forgings for Steam Turbine Generators Below 50MW
Subject Content and Scope of Application
JB/T 7029-93
This standard specifies the technical requirements, test methods, acceptance rules, certificates and marks for non-magnetic guard ring alloy steel forgings for steam turbine generators below 50MW.
This standard is applicable to the ordering, manufacturing and inspection of non-magnetic guard ring alloy steel forgings for steam turbine generators below 50MW. 2 Reference standards
GB222 Sampling method for chemical analysis of steel and allowable deviation of chemical composition of finished products GB223 Chemical analysis methods for steel and alloys
I3228 Metal tensile testing method
JB4010 Ultrasonic flaw detection method for steel guard ring for steam turbine generator JB/ZQ6158 Magnetic permeability determination method for weakly magnetic materials 3 Ordering requirements
3.1 The purchaser shall specify the grade and steel number of the standard forgings used, the corresponding technical requirements and inspection items, and other additional instructions in the order contract or order agreement.
3.2 When placing an order, the purchaser must provide the supplier with a rough machining drawing (finishing dimensions if necessary), and the sample location should also be marked on the drawing. It should be marked as follows:
Steel, No.
Forging grade × Number of this standard
4 Technical requirements
4.1 Manufacturing process
4.1.1 Refining
Steel for forgings should be smelted in an electric furnace, and other smelting processes may be used with the consent of the purchaser. 4.1.2 Head and tail cutting
The upper and lower ends of the steel ingot for forgings should be sufficiently cut off to ensure that the forgings have no shrinkage cavities and unacceptable segregation. 4.1.3 Forging
4.1.3.1 Forging should ensure that the entire cross section of the forging is fully forged. 4.1.3.2 Deformation strengthening should be carried out at room temperature or slightly above room temperature (15~~200C) by using appropriate strengthening methods to expand the hole, such as wedge expansion, hydraulic bulging or other methods that can ensure quality with the consent of the purchaser. 4.1.4 Heat treatment
4.1.4.1 Forgings can be solution treated after hot forming and before deformation strengthening. 4.1.4.2 After deformation strengthening, forgings should be heated to 320~350℃ at a speed of no more than 40℃/h, kept warm for 8~12h, and then slowly cooled to below 100℃ at a speed of no more than 40/h to eliminate residual stress. 4.1.5 Machining
4.1.5.1 Forgings shall be rough machined before deformation and strengthening. 4.1.5.2 Forgings shipped must be machined to the size and surface roughness indicated on the purchaser's drawings. 4.2 Chemical composition
The chemical composition of steel for forgings shall comply with the provisions of Table 1. Table 1
50Mn186r5
50Mn18Cr5N
50Mn18Cr4WN
4.3 Mechanical properties
Chemical composition
0.40~-0.6017.00~19.000.30~0.80Cr
≤0.025≤0.0803.506.00
0.40~~0.60 17.00~19.000.30~~0.80≤0.025≤0.0803.50~~6.00
0.400.60 17.00~19.000.30~0. 80≤0.025≤0.080
13.005.00
The mechanical properties of forgings shall comply with the provisions of Table 2. Table 2 Mechanical properties
Forging grade
4.4 Nondestructive testing
≥735
≥735
≥785
0.70~~1.20
4.4.1 Forgings shall not have cracks, folds or other defects that seriously affect their use. Local defects on the surface may be removed, but the depth of removal shall not exceed 75% of the finishing allowance.
When the purchaser makes a request, the supplier shall conduct ultrasonic inspection on the processed forgings. The inspection requirements are as follows: the entire outer cylindrical surface is inspected by transverse and longitudinal waves, and the two end surfaces are inspected by longitudinal waves; when inspecting by transverse waves, no defect signal exceeding the standard push line is allowed; b.
In any full circumference of 100mm width, there shall be no more than 8 defect signals between the standard line and the 1/2 standard line, and the distance between any two adjacent defects shall not be less than 50mm. The guard ring whose "V*-shaped groove reflection signal cannot be distinguished from the noise level due to the coarse grain or microstructure of the guard ring is rejected; d.
When inspecting by longitudinal waves, no defect larger than 3mm in equivalent diameter is allowed , and only 4 defects with an equivalent diameter of 2 to 3 mm are allowed within any full circumference of 100 mm width; f During longitudinal wave flaw detection, if the bottom wave disappears due to the presence of defects, the forging should be a defective product. 4.5 Magnetic permeability
When the magnetic field strength is 1.6×101A/m, the magnetic permeability of the forging should not be greater than 13.8×10-7H/m. 4.6 Residual stress
The residual stress of the forging shall not exceed 20% of the specified yield strength. 4.7 Dimensions and roughness
The dimensions, tolerances and surface roughness of the forgings shall comply with the requirements of the order drawings. 5 Inspection rules and test methods
5.1 Chemical composition analysis
JB/T 7029—93
5.1.1 The supplier shall conduct smelting analysis on each furnace of molten steel, and the results shall comply with the provisions of Table 1. 5.1.2 The purchaser shall conduct a review analysis on the finished product, and the sample shall be taken from any point on the inner ring of the extended section of the forging, or from the mechanical properties sample. 5.1.3 Chemical composition analysis shall be carried out in accordance with GB223 and relevant analysis methods. 5.2 Mechanical properties inspection
5.2.1 The tensile test shall be carried out in accordance with GB228. 5.2.2 The performance sample shall be cut from the specified extended section after deformation strengthening and stress relief treatment. The mechanical properties sample is taken from the outer ring by the supplier and from the inner ring by the purchaser. Two tensile specimens are taken at relative positions of the test rings. 5.2.3 For any forging, due to the expansion of defects in the sample during the test, its mechanical properties test results cannot meet the specified requirements, and the defects are not If it is caused by fracture and crack, it is allowed to take two adjacent samples for retest. If one sample is still unqualified after the retest, it should be processed again. For the reprocessed forgings, sample inspection shall be carried out in accordance with Article 5.2.2 of this standard. 5.3 Non-destructive testing
Ultrasonic flaw detection of forgings shall be carried out in accordance with JB4010 method. 5.4 Magnetic permeability determination
The sample and test method shall be carried out by the purchaser in accordance with JB/ZQ6158. 5.5 Residual stress test
5.5.1 The residual stress test shall be carried out by the ring cutting method. When other methods are used, the consent of the purchaser shall be obtained. 5.5.2 The ring cutting method is to cut a 25mm×25mml ring at the same end of the mechanical properties test ring, and calculate the residual stress by measuring the average deformation of the ring before and after cutting.
The residual stress calculation formula is:
α= E8/D
Residual stress, MPa;
·-·Algebraic value of diameter increment, mm;bZxz.net
Outer diameter of the ring before cutting, mm:
E--Elastic modulus of the material, MPa.
6 Acceptance and certificate of conformity
6.1 The forgings shall be accepted by the supplier's quality inspection department in accordance with this standard, and the buyer shall re-inspect in accordance with this standard. 6.2 The supplier shall provide the buyer's inspector with necessary convenient conditions so that the buyer's inspector can carry out his work, and the buyer's factory inspector shall not cause unnecessary obstruction to the supplier's production. Unless otherwise specified, all inspections shall be carried out by the supplier (except for the recheck analysis test). 6.3 The supplier shall provide the buyer with a certificate of conformity when the forgings leave the factory. The certificate of conformity shall include the following: a.
Contract number, melting furnace number, order forging drawing number and grade number; chemical composition analysis results;
Mechanical property test results;
Residual stress measurement results;
Ultrasonic test results, including defect distribution diagram; r. Solution treatment and stress relief tempering temperature, holding time and strengthening method; g.
Supplementary required test results.
6.4 After the forgings are accepted by the supplier, if unacceptable defects are found during the buyer's re-inspection and processing, the buyer shall promptly notify the supplier and the two parties shall negotiate to resolve the problem.
7 Marking and Packaging
7.1 The supplier shall mark the supplier's factory name or logo, order contract, order drawing number, smelting furnace number and forging card number on the end face of each forging. 1085
JB/T7029-93
The surface of each forging shall be fully coated with rust inhibitor to prevent corrosion during transportation. 7.3 Packaging and shipment should avoid damage to forgings when they are transported to the buyer. Additional Notes:
This standard is proposed and managed by the Deyang Large Castings and Forgings Research Institute of the Ministry of Machinery Industry. This standard is drafted by the Deyang Large Castings and Forgings Research Institute. The main drafters of this standard are Zhu Jiexiu, Zhang Xiushan, Chen Yuqian and Liu Xiaoguang. 1086
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