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 certificate and marking, etc. of large forgings for general purpose.
This part is applicable to the ordering, manufacturing and inspection of large carbon steel and structural alloy forgings forged freely by water (oil) press and forging hammer.
2 Normative References
The following normative documents contain provisions which, through reference in this part, constitute provisions of this part. For dated reference, subsequent amendments to, or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this part are encouraged to study whether the latest edition of these documents is applicable. For undated references, the latest edition of the normative document referred to 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 4949:1980)
GB/T 228 Metallic Materials-Tensile Testing at Ambient Temperature [GB/T228-2002, eqv ISO 6892:1998 (E)]
GB/T 229 Metallic Materials-Charpy Notch Impact Test (GB/T229-1994, 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 Standard Diagrams for Macrostructure and Defect of Structural Steels
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, ASTME112: 1996, MOD)
GB/T 10561 Steel-Determination of Content of Non-metallic Inclusion-Micrographic Method Using Standard Diagrams (GB/T 10561-1989, eqv ISO 4967: 1979)
JB/T 5000.15 Heavy Mechanical General Techniques and Standards-Part 15: Non-destructive Inspection of Forged Steel
3 Order Requirements
3.1 The demander shall specify the standards adopted, forging groups, steel grades, corresponding technical requirements and inspection items as well as other additional information in the order contract or order agreement.
3.2 The demander shall provide order drawings.
3.3 Supplementary requirements shall be negotiated by both the supplier and demander.
4 Specifications
4.1 Manufacturing Process
4.1.1 Smelting
If no special requirement is made by the demander, then the smelting process shall be determined by the supplier.
4.1.2 Forging
4.1.2.1 The upper and lower parts of the ingots shall be provided with sufficient removal in order to make the finished forgings free from shrinkage and severe segregation. 4.1.2.2 Forgings shall be forged and formed on forging press with adequate capacity in order to ensure thorough internal forging.
4.1.2.3 If ingots are adopted for forging, their forging ratio shall be generally no less than 3 for those un-upset and no less than 2.5 for those upset. The forging ratio of flanges shall not be less than 1.7. If advanced forging methods are adopted, their forging ratio may be appropriately reduced.
4.1.2.4 If forge bars or mill bars are adopted for forging, the forging ratio shall be generally not less than 1.5 and that of the flanges not less than 1.3.
4.1.2.5 The forgings, after forging, shall be subjected to heat treatment with a certain method to reduce the forging stress and make forgings be with good machining property. As for those forgings for which the post-forging heat treatment is taken as the final heat treatment, they shall meet the technical requirements of drawing.
4.1.2.6 Forms and dimensions of forgings shall meet the requirements specified in the forging drawing and process documents.
4.1.3 Heat treatment
Final heat treatment of the forgings shall be carried out based on the delivery state specified in the order contract or drawing.
4.1.4 Machining
Machining of the forging shall be in accordance with the dimensions and surface roughness specified in the order drawing.
4.2 Chemical Compositions
Chemical compositions of the steel shall meet the defined standards specified in the order contract or drawing.
4.3 Mechanical Properties
Mechanical properties of the forging shall meet those specified in the order contract or drawing.
4.4 Others
The demander, when necessary, may put forward non-destructive inspection, elevated temperature strength, low temperature flexibility, grain size, inclusion, metallurgical structure and other supplementary requirements, whose test methods and acceptance standards shall be determined through negotiation by both sides.
Foreword II
1 Scope
2 Normative References
3 Order Requirements
4 Specifications
4.1 Manufacturing process
4.2 Chemical compositions
4.3 Mechanical Properties
4.4 Others
5 Test Rules and Test Methods
5.1 Chemical Composition Analysis
5.2 Mechanical Test
6 Acceptance, Re-inspection and Re-heat Treatment
7 Quality Certificate
8 Printing and Packing
Figure 1 Axial or Square and Rectangular Forging
Figure 2 Hollow Forging
Figure 3 Disc Forging
Figure 4 Ring Forging
Table 1 Permissible Deviation of Common Straight Carbon Steel and Low-alloy Steel Product Analysis
Table 2 Permissible Deviation of Qualitative Carbon Steel and Alloy Structural Steel Product Analysis
Table 3 Acceptance and Grouping of Forgings
Table 4 Reduction Value of Tangential and Transverse Mechanical Properties
