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JB/T 1268-2014 PDF in English


JB/T 1268-2014 (JB/T1268-2014, JBT 1268-2014, JBT1268-2014)
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JB/T 1268-2014: PDF in English (JBT 1268-2014)

JB/T 1268-2014
JB
MECHANICAL INDUSTRY STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.85
J 32
Registration number. 47212-2014
Replacing JB/T 1268-2002 (part), JB/T 7029-2004
Mn18Cr5 series nonmagnetic retaining ring forgings
for turbine generator - Technical specification
ISSUED ON. JULY 09, 2014
IMPLEMENTED ON. NOVEMBER 01, 2014
Issued by. Ministry of Industry and Information Technology of PRC
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 Ordering requirements ... 6 
4 Manufacturing process ... 6 
4.1 Smelting ... 6 
4.2 Forging ... 6 
4.3 Heat treatment... 7 
4.4 Machining ... 7 
4.5 Welding ... 7 
5 Technical requirements ... 7 
5.1 Chemical composition ... 7 
5.2 Mechanical properties ... 7 
5.3 Residual stress ... 8 
5.4 Grain size ... 8 
5.5 Non-destructive testing... 8 
5.6 Magnetic permeability ... 9 
5.7 Dimensions and surface roughness ... 9 
6 Inspection rules and test methods ... 9 
6.1 Chemical composition analysis ... 9 
6.2 Mechanical properties test ... 10 
6.3 Determination of residual stress ... 10 
6.4 Grain size test ... 10 
6.5 Non-destructive testing... 11 
6.6 Magnetic permeability testing ... 11 
6.7 Retest ... 11 
7 Acceptance and quality certificate ... 11 
8 Markings and packaging ... 12 
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard replaces JB/T 1268-2002 “Specification for nonmagnetic
retaining ring forgings for 50MW to 200MW turbine generators” and JB/T 7029-
2004 “Specification for nonmagnetic retaining rings forgings used below 50MW
turbine generator”.
This standard is based on JB/T 1268-2002 and incorporates part of JB/T 7029-
2004. As compared with JB/T 1268-2002, the main technical changes of this
standard are as follows.
- In the manufacturing process, ADD the expression of welding, forgings
cannot be welded during the manufacturing process (see 4.5);
- In accordance with the provisions of the new standard, MODIFY some
symbols in the mechanical properties of Table 2, RE-MODIFY the forging
grades and performance indicators, ADD the mid-section of the table (see
5.2; 4.3 of 2002 version);
- CHANGE the residual stress on the forgings not exceeding the lower limit
of the yield strength specified in Table 2 from 20% to 10%, ADD the concept
of absolute residual stress (see 5.3; clause 4.4 of 2002 version);
- MODIFY the grain size specification (see 5.4; 4.5 of 2002 version);
- MODIFY the technical requirements for the disappearance of bottoms due
to defect when using longitudinal wave detection in the ultrasonic testing
(see 5.5.3.5; 4.6.3.5 of the 2002 version);
- With reference to the technical conditions of foreign orders, CHANGE the
magnetic permeability of the forged piece shall not be greater than 13.8 x
10-7 to the relative permeability μr of the forged piece shall not be greater
than 1.05 (see 5.6; 4.7 of the 2002 version);
- DELETE the 1Mn18Cr18N forgings, INCLUDE the forgings into the
“Mn18Cr18N series nonmagnetic retaining ring forgings for turbine
generator - Technical specification” (see 4.2 and 4.6 of 2002 version).
This standard was proposed by China Machinery Industry Federation.
This standard shall be under the jurisdiction of the National Standardization
Technical Committee for Casting and Forging Parts (SAC/TC 506).
Drafting organizations of this standard. Harbin Institute of Electrical Engineering,
Erzhong Group (Deyang) Heavy Equipment Co., Ltd., Dongfang Motor Co., Ltd.,
Mn18Cr5 series nonmagnetic retaining ring forgings
for turbine generator - Technical specification
1 Scope
This standard specifies the ordering requirements, manufacturing process,
technical requirements, inspection rules and test methods, quality certificates
and marking for the Mn18Cr5 series nonmagnetic retaining ring forgings for
turbine generator.
This standard applies to the ordering, manufacturing and inspection of
Mn18Cr5 series nonmagnetic retaining ring forgings for turbine generator.
2 Normative references
The following documents are essential to the application of this document. For
the dated documents, only the versions with the dates indicated are applicable
to this document; for the undated documents, only the latest version (including
all the amendments) are applicable to this standard.
GB/T 222 Permissible tolerances for chemical composition of steel products
GB/T 223 (all parts) Steel and alloy chemical analysis method
GB/T 228.1 Metallic materials - Tensile testing - Part 1. Method of test at
room temperature
GB/T 3656 Method of coercivity measurement for magnetically soft materials
by pull out procedure
GB/T 4336 Carbon and low-alloy steel - Determination of multi-element
contents - Spark discharge atomic emission spectrometric method (routine
method)
GB/T 6394 Metal - Methods for estimating the average grain size
GB/T 20124 Steel and iron - Determination of nitrogen content - Thermal
conductimetric method after fusion in a current of inert gas
JB/T 4010 Ultrasonic examination of turbine - Generator steel retaining rings
ASTM E165 Standard practice for liquid penetrant examination for general
industry
3 Ordering requirements
3.1 The purchaser shall specify in the ordering contract or technical agreement
the standards adopted, material grades, forging strength grades, corresponding
technical requirements and inspection items, and other additional instructions.
3.2 When ordering, the purchaser shall provide the supplier with a roughing
pattern (if necessary, provide the finishing size), and shall also indicate the
sampling position on the pattern.
3.3 The purchaser shall mark the selected material grade on the pattern and
mark the number of this standard and the selected forging grade on the
technical conditions. And mark it as follows.
Material grade
Forging strength level x This standard number
4 Manufacturing process
4.1 Smelting
The steel used in forgings shall be subject to electric furnace plus external
furnace refining; with the consent of the purchaser, it may also use other
smelting methods that guarantee quality.
4.2 Forging
4.2.1 The upper and lower ends of the steel ingots for forgings shall have
sufficient margin, to ensure that the forgings have no shrinkage or severe
segregation.
4.2.2 Forgings shall be forged on a forging press with sufficient capacity, to
ensure that the entire cross section of the forging is fully forged.
4.2.3 Forgings shall be deformed with appropriate methods at room
temperature or slightly higher than room temperature, such as wedge reaming,
hydraulic bulging and so on.
defect signal between the reference line and the 1/2 reference line shall not
exceed 4 and the distance between any adjacent defects shall not be less than
50 mm.
5.5.3.3 The retaining ring which cannot differentiate the V-notch reflection signal
from the noise level due to the coarse grain or microstructure shall be rejected.
5.5.3.4 In case of longitudinal wave testing, there shall be no defects with an
equivalent diameter of more than 3 mm. In the full circumference range of any
100 mm width, the number of defects having an equivalent diameter of Φ2 mm
~ Φ3 mm shall not exceed 4.
5.5.3.5 When the longitudinal wave is used for the testing at the end face and
the circumferential face, the forgings shall be regarded as unqualified when the
bottom wave disappears due to the presence of a recording defect.
5.6 Magnetic permeability
When the magnetic field strength is 100Oe (Oester, 1Oe = 79.57 A/m), the
relative magnetic permeability μr of the forging shall not be greater than 1.05.
5.7 Dimensions and surface roughness
Forging dimensions, tolerances, and surface finishes shall all meet the
requirements of the ordering pattern.
6 Inspection rules and test methods
6.1 Chemical composition analysis
6.1.1 The supplier shall conduct smelting analysis for each molten steel, to
determine the mass fraction of the elements specified in Table 1. Smelting
analysis shall be sampled during molten steel casting.
6.1.2 The purchaser shall carry out the finished product review analysis. The
sample shall be taken from any point of the 1/2 wall thickness of the forging
extension, it may also be taken from the mechanical property sample.
6.1.3 Analysis of chemical composition shall be conducted in accordance with
the methods specified in GB/T 223, GB/T 4336, GB/T 20124 or other methods
that can guarantee the quality of analysis.
6.4.2 The grain size sample is taken from the mechanical property test ring and
measured on a longitudinal section in the radial direction.
6.5 Non-destructive testing
6.5.1 Ultrasonic testing of forgings shall be carried out in accordance with JB/T
4010.
6.5.2 Liquid penetrant testing shall be conducted in accordance with ASTM
E165.
6.6 Magnetic permeability testing
Magnetic permeability testing is carried out in accordance with the provisions
of GB/T 3656.
6.7 Retest
6.7.1 If a result in the mechanical property test does not meet the requirements,
two specimens may be taken on the forging adjacent to the original sample for
retesting. The retest results of the two specimens shall all meet the specified
requirements.
6.7.2 If the test results are not qualified due to cracks and white spots, it shall
not perform retest.
7 Acceptance and quality certificate
7.1 The supplier shall test the forgings in accordance with this standard and the
items specified in the contract. The testing results shall comply with the
specified requirements. The certificate shall have the signature and chop of the
quality testing person in charge of the supplier.
7.2 The purchaser may select certain items for retest in accordance with the
provisions of this standard and the contract. After the forgings are accepted by
the supplier, if the purchaser finds that the forgings do not meet the
requirements in the retest, subsequent processing or inspection, the purchaser
shall notify the supplier in a timely manner and be resolved through consultation
between both parties.
7.3 The supplier shall provide the necessary conditions to the purchaser’s
acceptance personnel, so that the acceptance inspection personnel of the
purchaser can perform site acceptance work. The inspectors of purchaser shall
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Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.