JB/T 8888-1999 JB/T 8888-1999 Test method for measuring residual stress in steam turbine and turbogenerator rotor forgings by ring core method JB/T8888-1999 Standard download decompression password: www.bzxz.net

[C5 77.140.85
Machinery Industry Standard of the People's Republic of China
JB/T8888-1999
Test method for measuring residual stresses by the ring-coremethod in rotor forgings for turbiae and generator1999-06-28, issued
National Machinery Industry Standard
2000-01-01 Implementation
This standard is formulated for the following six product technical parts on residual stress measurement, these six technical parts are: JB/T7025-J993 "Technical conditions for forgings of steam turbine rotors and main shafts below 25MW", JB/T1265-1993 "Technical conditions for forgings of 25-200MW steam turbine rotors and raw shafts", JB/T7027-1993 "Technical conditions for forgings of 300-600MW steam turbine rotors", JB/T7026--1993 "Technical conditions for forgings of steam turbine generator rotors below 50MW", JB/T1267-1993 (50 ~200MW steam turbine generator rotor forging technical conditions", JB/T7178-1993 (309-600MW steam turbine generator rotor forging technical conditions". From the implementation of this standard, the test method of measuring residual stress by ring cutting method in the above six product technical conditions will be gradually replaced. This standard is proposed and coordinated by Yunyang Large Forging Research Institute, and the drafting unit of this standard is Zhengzhou Machinery Research Institute. The main drafter of this standard is Lian Huinan
China Machinery Industry Standard
Test Method for Measuring Residual Stress of Steam Turbine and Steam Turbine Generator Rotor Forgings by Ring Core Method
Test method for measuring residual stress on the rmg coremrtbod in rotor forgins for turbines and turbine generators by ring core method, test equipment and measuring procedures.
This standard is applicable to the residual stress measurement of various rotors in JB/T7025, JB/T1265, JB/T7027. JB/T7026, JB1267 and JB/T7178, and is also applicable to the residual stress measurement of other shaft forgings. Reference standards
The provisions contained in the following standards constitute the provisions of this standard by reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, so the parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T13992—1992 Electric limit strain gauge
JB/T1265—1993
JB/T1267—1993
JB/T7025—1993
JB/T7026—1993
JB/T7027—1993
JB/T71781993
3 Measurement method
25~200MW steam turbine rotor body and main shaft forging technical conditions 50-200MW steam turbine generator rotor forging technical conditions Technical conditions for turbine rotor bodies and shaft parts below 25MW Technical conditions for turbine generator rotor winding parts below 50MW Technical conditions for turbine rotor forgings of 300~600MW Technical conditions for turbine generator rotor forgings of 300~600MW 3.1 Paste a double-axis (mutually-stationary) sensitive resistance strain rosette on the measuring plate of the rotor outer surface, and the two sensitive directions are aligned with the circumferential and axial directions of the rotor respectively. 3.2 Mill a ring with an inner diameter of 5mm around the center of the strain rosette. The depth is 2mm each time and 4mm each time, as shown in the figure.
3.3 The residual stress on the boundary of the ring core must be released, and the released strain is measured by a strain gauge. 3.4 The difference between the two released strains and the residual stress on the rotor surface at a depth of 2-4mm has the following relationship:,=(2.150,.379)
,(0.379+2150)
Where: T,. π, — converted to the circumferential and axial residual stresses in the depth range of 2-4mm below the surface, MPa;, the difference between the circumferential and axial loading strains, that is, 4 e=: [2=2mm)- 8, (z-4mm)
Approved by the State Machinery Industry Bureau on 1999-06-2%
Implementation on 2000-01-01
88988-1959
48=e, (z-2mm)-
E-, converted to the elastic operation of the material, MPA. (2-4mm)
1 and 2 Strain gauge payment
1 Symbol definition
4 Test equipment
4.1 Resistance strain gauge
4.1.1 Double-axis electric seat strain rosette with 90° digital sense (such as BI1-120-1.5BB) or double-axis resistance strain rosette with 90° sensitive sense (such as BJ-120.5C) can be used. 4.1.1 The outer size of the resistance strain rosette is the inner diameter of the ring groove. 4.1.3 When using the resistance strain gauge (paste, lead, protective coating), the manufacturer's recommendations should be followed, and the resistance strain gauge should be protected during milling.
4.1 The strain resolution of the strain gauge should be ±10-, and the accuracy and accuracy of the measurement crown should be at least ±2×10-°. 4.3 Clamp Ring Device
4.3.1 Any sharp ring that can be easily mounted on the outer surface of the shaft is suitable for installation. The clamp ring is cut out of the center end of the chamber. The resistance strain gauge measuring wire passes through the main shaft and is connected to the strain gauge. 4.3.2 The inner diameter of the die should be Φ15mm. The width of the ring groove is not strictly specified and can be 2mm or 2.5mm. 4.3.3 When the ring groove is controlled, the depth can be accurately measured or controlled. The device should have a mechanism to measure or control the depth of the ring die. The depth measurement and control error should not exceed ±0.05mm. 5. The position of the residual stress measuring point of the rotor key type should be in accordance with the technical conditions of JB/T7025, JB/T7(27, JHF7026, JB1267, and JBT7178. The position of the super-surface opposite to the ring test should be taken, and 3 measuring points should be evenly distributed. 2. The measurement step should be 2.
6. Surface preparation of measuring point
JB/T8BBB—1999
6.1.1 The surface preparation before pasting the resistance strain gauge must meet the requirements of the adhesive for pasting the electric strain gauge. 61.2 The pasting direction and the ring groove position of the resistance strain gauge need to be marked. 61.3. The surface needs to be cleaned and degreased. 6.2 Pasting of resistance strain gauge
The stability of the pasting of the resistance strain gauge should be confirmed, and the insulation distance to the ground should not be less than 200M. 6.3 When installing the chain ring device and connecting the adjustment disk line, the misalignment between the ring center and the electric strain rosette center is allowed to be ±0.5mm. 6.4 Ring groove and strain measurement
6.4.1 The first ring is milled to a depth of 2mm, and the machine is stopped to measure the strain reading of each resistance strain gauge. The second ring is milled to a depth of 4mm, and the machine is stopped to measure the strain reading of each resistance strain gauge. 6.4.2 When the sharpening cutter is inserted into the ring, the axial feed should be light and slow to allow sufficient heat exchange. The sharpening speed should not exceed 100r/min, and the axial feed speed should not exceed 0.5mm/min
The strain gauge period
7.1 From the measured strain difference 848, the circumferential and axial residual stresses are calculated according to formula (1). 7.2 When the milling cutter washes the ring groove, residual stress will be generated in the part. , which has an impact on the accuracy of the test results. A test piece that produces less residual stress should be selected. If there is no previous experience to draw on, it is recommended to conduct a milled residual stress test, that is, to paste a resistance strain rosette opposite to the future test on a stress-free test block of the same material as the rotor, mill a ring groove of the same diameter, measure the strain at depths from 2 mm to 4 mm at more than 5 test notches, and take the average value. If necessary, it is recommended to subtract the above strain average value from the rotor relief strain measurement value (m/s, m/s, 4,), and then calculate the residual stress according to formula (8). 8 Test report
8.1 A test report should be written after the residual stress measurement is completed. 8.2 The test report shall include the following contents: Www.bzxZ.net
a) Forging name:
b) Forging production number, furnace number, card number [workpiece serial number; c) Forging steel type;
d) Heat treatment state of forging;
) Main mechanical properties of forging materials:
Circumferential and axial residual stress measurement results of plated parts: 2) The bag residual stress results of various forgings are respectively evaluated according to the provisions of JD/T7025, J/T7027, JB/T7026, JB1267, and JB/T717B: h) Test date:
) Signature of the test personnel.
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