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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard was proposed by China Machinery Industry Federation.
This standard is under the jurisdiction of National Technical Committee on Heavy Forgings of Standardization Administration of China (SAC/TC 506).
Heavy alloy structural steel forgings - Technical specification
1 Scope
This standard specifies the order requirements, manufacturing process, technical requirements, inspection rules, test methods, acceptance, quality certificate, marking and packaging etc. of alloy structural steel forgings.
This standard applies to the order, manufacturing and inspection of heavy alloy structural steel forgings for general use.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 223 (all parts) Methods for chemical analysis of iron, steel and alloy
GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature (GB/T 228.1-2010, ISO 6892-1:2009, MOD)
GB/T 229 Metallic materials - Charpy pendulum impact test method (GB/T 229-2007, ISO 148-1:2006, MOD)
GB/T 231.1 Metallic materials - Brinell hardness test - Part 1: Test method (GB/T 231.1-2009, ISO 6506-1:2005, MOD)
3 Order requirements
3.1 The purchaser shall specify the name, grade, material designation, delivery state, and supply quantity of forgings in the order contract.
3.2 The purchaser shall provide the order drawing.
3.3 When the purchaser has additional requirement, it shall be agreed between both parties.
4 Manufacturing process
4.1 Smelting
Steel used for forgings shall be smelted in basic electric furnace. As agreed by the purchaser, other smelting method ensuring the quality may also be adopted.
4.2 Forging
The forgings shall be forged from steel ingot or billet. There shall be sufficient metal removal at both ends of the steel ingot so as to ensure no shrinkage cavity or severe segregation on the forging body. The forging shall be forged on the forging and pressing equipment with adequate capability to ensure full forging and uniform microstructure. Forgings are allowed to be forged with multiple length. Forgings shall be slowly cooled after forging to prevent cracking.
4.3 Heat treatment
Forgings shall be subject to high temperature tempering or normalizing plus tempering or be cooled slowly by other modes to improve the microstructure and machining performances. Normalizing plus tempering or quenching and tempering treatment processes may be adopted according to the material designation and strength grade of forgings. Heat treatment with multiple length is allowed for forgings.
4.4 Machining
4.4.1 The supplier may decide whether to carry out rough processing to all the surfaces of the forgings before the performance heat treatment according to the specific conditions.
4.4.2 The requirements for the dimensions, tolerances and surface roughness of the delivered forgings shall meet the requirements of the purchaser's order drawings.
4.5 Defect removal and repair welding
4.5.1 Local defects of forgings may be removed, but the defect cleaning depth shall not exceed 75% of the machining allowance.
4.5.2 As for the defective forgings, they may be restored by repair welding only after that the welding assessment result is in accordance with the mechanical properties of the same material designation and approval is obtained from the purchaser.
5 Technical requirements
5.1 Chemical compositions
5.1.1 The supplier shall conduct smelting analysis on each furnace (each pack) of molten steel, and the analysis results shall meet the requirements of Table 1. The weighted average analysis result shall be reported when multiple furnaces are combined.
5.1.2 When the purchaser has special requirements, the supplier shall carry out finished product analysis for the forgings, and its specific requirements shall be specified in the contract or drawing. The results of the finished product analysis shall meet the requirements of Table 1 but are allowed to have the deviations specified in Table 2.
Foreword II
1 Scope
2 Normative references
3 Order requirements
4 Manufacturing process
4.1 Smelting
4.2 Forging
4.3 Heat treatment
4.4 Machining
4.5 Defect removal and repair welding
5 Technical requirements
5.1 Chemical compositions
5.2 Mechanical properties
5.3 Hardness
5.4 Non-destructive testing
6 Inspection rules and test methods
6.1 Chemical composition analysis
6.2 Mechanical property tests
6.3 Hardness inspection
6.4 Retest
6.5 Re-heat treatment
7 Acceptance and quality certificate
8 Marking and packaging
Table 1 Chemical composition
Table 2 Allowable deviations for chemical compositions of finished products
Table 3 Mechanical properties
Table 4 Grades and inspection items
Figure 1 Sampling positions of solid axle, square and rectangular forgings
Figure 2 Sampling positions of hollow forgings
Figure 3 Sampling positions of disk forgings
Figure 4 Sampling positions of ring forgings
