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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces JB/T 6398-2006 Heavy stainless acid resistant steel and heat resistant steel forgings and the following main technical changes have been made with respect to JB/T 6398-2006:
——the normative references are added (see Clause 2; Clause 2 of Edition 2006);
——provisions on order contract in order requirements are modified (see 3.1; 3.1 of Edition 2006);
——witness items about the product manufacturing process in order requirements are added (see 3.3);
——manufacturing process requirements for smelting, forging, heat treatment and machining are modified (see 4.1~4.4; 4.1 of Edition 2006);
——manufacturing process requirements for welding repair are added (see 4.5);
——Table 2 in the original standard is deleted and revised to comply with GB/T 222 (see 5.1.2; 4.2.2 of Edition 2006);
——according to GB/T 20878-2007, the expression methods of material designation in Tables 1 and 2 are modified; the material designation "1Cr18Ni9Ti" is canceled, and the contents of P and S in Table 1 are modified (see Tables 1 and 2; Tables 1 and 3 of Edition 2006);
——hardness value in mechanical performance is modified (see Table 2; Table 3 of Edition 2006);
——non-destructive testing requirements and inspection criteria are added (see 5.5 and 6.4);
——requirements and test criteria for other inspection items are added (see 5.6 and 6.5);
——hardness test content is modified (see 6.3; 5.2.3 of Edition 2006);
——retest contents are modified (see 6.6; 6.2 of Edition 2006).
——the requirements of re-heat treatments are modified (see 6.7; 6.2 of Edition 2006);
——the specific contents of acceptance and quality certificate are modified (see Clause 7; 6.1 and Clause 7 of Edition 2006);
——the requirements for marking, cleaning, packaging and transportation are modified; contamination-proof requirements for stainless steel are added (see Clause 8; Clause 8 of Edition 2006).
This standard was proposed by the China Machinery Industry Federation.
This standard is under the jurisdiction of the National Technical Committee on Heavy Casting and Forging of Standardization Administration of China (SAC/TC 506).
The previous editions of this standard are as follows:
——JB/T 6398-1992, JB/T 6398-2006.
Heavy stainless acid resistant steel and heat resistant steel forgings - Technical specification
1 Scope
This standard specifies the order requirements, manufacturing process, technical requirements, inspection rules, test methods, acceptance, quality certificate, marking, cleaning and packaging of austenitic and martensitic heavy stainless acid resistant steel and heat resistant steel forgings with general requirements.
It is applicable to the order, manufacturing and inspection of heavy stainless acid resistant steel and heat resistant steel forgings (hereinafter referred to as 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 222 Permissible tolerances for chemical composition of steel products
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 228.2 Metallic materials - Tensile testing - Part 2: Method of test at elevated temperature
GB/T 229 Metallic materials - Charpy pendulum impact test method
GB/T 231.1 Metallic materials - Brinell hardness test - Part 1: Test method
GB/T 4334-2008 Corrosion of metals and alloys - Test methods for intergranular corrosion of stainless steels
GB/T 6394 Determination of estimating the average grain size of metal
GB/T 10561 Steel - Determination of content of nonmetallic inclusions - Micrographic method using standards diagrams
JB/T 8467 Ultrasonic testing for steel forgings
3 Order requirements
3.1 The purchaser shall specify name, material designation, technical requirements, inspection items, delivery condition and supply quantity of forgings and other additional requirements in the order contract.
3.2 The purchaser shall provide the order drawings and technical documents agreed by the supplier and the purchaser.
3.3 When the purchaser needs to witness the production and test of forgings, it shall propose the specific stages of production and test to be attended.
4 Manufacturing process
4.1 Smelting
4.1.1 Steel ingots for forgings shall be smelted by electric furnace and vacuum refined by ladle furnace, or other refining methods such as electroslag remelting agreed by the purchaser.
4.1.2 Without the consent of the purchaser, the supplier shall not intentionally add elements not listed in Table 1 to the steel, and shall also take reasonable measures to prevent the introduction of elements that may affect the corrosion resistance and mechanical performances of the steel from steel-making scrap steel or other materials.
4.2 Forging
4.2.1 The sprue and riser of steel ingot shall have adequate cut-off quantity so as to ensure that the forging is free from injurious defects like shrinkage cavity and excessive segregation.
4.2.2 Forgings shall be forged on a forging press with sufficient capacity to fully forge the entire section to the shape and size of the finished forging as much as possible. When ingots or billet are used for forging, forging ratio of forging’s principal section shall not be less than 3 (that of electroslag remelted steel not less than 2); while where mill bars are used, it shall not be less than 1.6.
4.3 Heat treatment
4.3.1 Austenitic profile steel shall be subjected to solution heat treatment, while martensitic profile steel shall be subjected to quenching and tempering. Change of heat treatment state by the supplier shall be agreed by the purchaser.
4.3.2 All heat treatment processes (including heat treatment holding temperature and its deviation, holding time, heating rate and cooling method, etc.) shall be recorded. The temperature deviation of forgings during heat treatment holding time shall not exceed ±10℃.
4.4 Machining
All machining (such as cutting, sawing or grinding) shall be carried out before performance heat treatment as far as possible to avoid cold hardening of the material, unless the cold hardening can be removed by subsequent machining.
4.5 Welding repair
4.5.1 Welding repair may be conducted upon the agreement of the purchaser.
4.5.2 The supplier shall submit welding process specification (WPS), welding process qualification report (PQR) and welding personnel qualification document to the purchaser. Non-destructive testing methods and qualification levels before and after welding repair shall be agreed upon by the supplier and the purchaser.
4.5.3 Drawings for forging's welding repair parts, depth and area, welding materials and non-destructive testing report shall be provided by the supplier to the purchaser.
Foreword i
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 Welding repair
5 Technical requirements
5.1 Chemical composition
5.2 Mechanical performance
5.3 Uniformity of hardness
5.4 Surface quality, shape and dimensional tolerance
5.5 Non-destructive testing
5.6 Other requirements
6 Inspection rules and test methods
6.1 Chemical composition analysis
6.2 Mechanical performance test
6.3 Hardness test
6.4 Non-destructive testing
6.5 Other test methods
6.6 Retest
6.7 Re-heat treatment
7 Acceptance and quality certificate
7.1 Acceptance
7.2 Quality certificate
8 Marking, cleaning and packaging
Table 1 Chemical composition
Table 2 Mechanical performance
