JB/T 5000.8-2007 English PDF (JBT5000.8-2007)

This Part of the JB/T 5000 specifies the ultrasonic, magnetic-powder and penetration testing methods and quality grades of forged steel. This Part applies to non-destructive testing of forged steel for heavy machinery. Non-destructive testing methods as specified in this Part may involve hazardous materials, operations and equipment, so the non-destructive testing personnel shall comply with relevant safety and health regulations.

JB/T 5000.8-2007
JB
MECHANICAL INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
ICS 25.120.20
H 90
Registration number. 21702-2007
Replacing JB/T 5000.8-1998
Heavy mechanical general techniques and standards -
Part 8. Forging
ISSUED ON. AUGUST 28, 2007
IMPLEMENTED ON. FEBRUARY 01, 2008
Issued by. National Development and Reform Commission
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Ordering requirements ... 6
4 Technical requirements ... 6
4.1 Manufacturing process ... 6
4.2 Chemical composition ... 7
4.3 Mechanical properties ... 7
4.4 Others ... 7
5 Inspection rules and test methods ... 7
5.1 Analysis of chemical composition ... 7
5.2 Test of mechanical properties ... 9
6 Acceptance, re-inspection and re-heat treatment... 15
7 Quality certificate ... 15
8 Print packaging ... 15
Foreword
JB/T 5000 “Heavy mechanical general techniques and standards” is divided into 15 parts.
- Part 1. Check of product;
- Part 2. Oxygen cutting workpiece;
- Part 3. Standards welding;
- Part 4. Iron casting;
- Part 5. Non-ferrous casting;
- Part 6. Steel castings;
- Part 7. Repair welding for steel castings;
- Part 8. Forging;
- Part 9. Cutting;
- Part 10. Assembly;
- Part 11. Attached piping;
- Part 12. Paint;
- Part 13. Packing;
- Part 14. Non-destructive inspection of cast steel;
- Part 15. Non-destructive inspection of forged steel.
This part is the part 8 of the JB/T 5000.
This part replaces JB/T 5000.8-1998 “Heavy mechanical general techniques and standards - Part 8. Forging”.
As compared with JB/T 5000.8-1998, the main changes of this part are as follows.
- ADD the descriptions of Table 3.
- In 5.2.2.3, ADD the followings. when the forging’s thickness is more than 200 mm, it is allowed to cut the specimen side by side; when the forging’s heightening part is greater than 200 mm, it is allowed to cut the specimen side by side.
Heavy mechanical general techniques and standards -
Part 8. Forging
1 Scope
This part of JB/T 5000 specifies the technical requirements, inspection rules, test methods, quality certificates and markings for general purpose large forgings.
This part applies to the ordering, manufacturing, inspection of the large forgings of carbon steel and alloy structural steel which are free-forged by the hydraulic (oil) press and the forging hammer.
2 Normative references
The provisions in following documents become the provisions of this part through reference in this part of JB/T 5000. For the dated references, the subsequent amendments (excluding corrections) or revisions do not apply to this part; however, parties who reach an agreement based on this part are encouraged to study if the latest versions of these documents are applicable. For undated references, the latest version of the referenced document applies. GB/T 223 (All parts) Methods for chemical analysis of iron, steel and alloy GB/T 226 Etch test for macrostructure and defect of steels (GB/T 226-1991, neq ISO 4969.1980)
GB/T 228 Metallic materials - Tensile testing at ambient temperature [GB/T 228-2002, eqv ISO 6892.1998 (E)]
GB/T 229 Charpy notch impact test (GB/T 229-1994, eqv ISO 148.1983)
GB/T 231.1 Metallic materials - Brinell hardness test - Part 1. Test method [GB/T 231.1-2002, eqv ISO 6506-1.1999 (E)]
GB/T 1979 Diagram of a low magnification texture blemish grading of
structural steel
GB/T 4338 Metallic materials - Tensile testing at elevated temperature (GB/T 4338-1995, eqv ISO 738. 1989)
GB/T 6394 Metal - Methods for estimating the average grain size (GB/T
6394-2002, ASTM E 112.1996, MOD)
4.1.2.5 Forgings are heat-treated in a certain way after being forged, to reduce the forging stress and make it have good mechanical processing properties. For forgings which uses the post-forging heat treatment as final heat treatment, it shall meet the technical requirements of the drawings after heat treatment. 4.1.2.6 The shape and dimensions of the forgings shall be in accordance with the requirements of the forging’s drawings and process documents.
4.1.3 Heat treatment
The final heat treatment of the forgings shall be carried out in accordance with the delivery status as specified in the order contract or drawings.
4.1.4 Machining
The machining of forgings shall be in accordance with the dimensions and surface roughness as specified in the order drawings.
4.2 Chemical composition
The chemical composition of the steel shall comply with the requirements of the standards as specified by the ordering contract or the drawings.
4.3 Mechanical properties
The mechanical properties of the forgings shall comply with the requirements of the standards as specified by the ordering contract or the drawings. 4.4 Others
When the purchaser considers it necessary, it may propose the non-destructive testing, high-temperature strength, low-temperature toughness, grain size, inclusions, metallographic structure, other supplementary requirements. The inspection methods and acceptance criteria shall be determined by both parties through negotiation.
5 Inspection rules and test methods
5.1 Analysis of chemical composition
5.1.1 Melting analysis
5.1.1.1 It shall carry out sampling analysis at the time of pouring of each furnace 6 Acceptance, re-inspection and re-heat treatment.
6.1 Forgings are not allowed to have visible cracks, folds or other appearance defects that may affect the use. Local defects may be removed, but the depth of removal shall not exceed 75% of the machining allowance. Defects on the non-machined surface of the forging shall be cleaned and smoothed, the depth of removal shall not exceed the deviation of the forging’s dimensions of the manufacturer. For defects that exceed the machining allowance and forging’s dimensional deviation, the weld can be removed and repaired after obtaining the consent from the purchaser.
6.2 Forgings are not allowed to have white spots, internal cracks or residual shrinkage cavities.
6.3 In the test of mechanical properties, if the tested specimen is defective, as long as the noncompliance of mechanical properties is not due to cracks and white spots, it is allowed to take sample again for testing, as the initial test result. 6.4 When the initial test result of a certain mechanical property does not meet the requirements, it is allowed to take double sample near the unqualified sample to carry out the retest, the results of the retest shall all meet the requirements. If any of the results after the retest is still unsatisfactory, the forgings may be reheat-treated and resampled for testing. The number of reheat treatments (re-austenification) must not exceed two.
7 Quality certificate
The quality certificate contains the forging’s name, designation, weight, quantity; contract number, drawing number, furnace number, forging number; various inspection results as specified in the contract and drawings.
8 Print packaging
8.1 The supplier shall print the contract number, furnace number, forging number in the forging equivalent to the steel ingot’s nozzle end.
8.2 The surface of machined forgings shall be protected against rust. Forgings are packaged to avoid damage during transportation.