Heavy low alloy steel castings

Transcription

1 ICS J 31 Recording No.: MECHANICAL INDUSTRY STANDARD OF THE PEOPLE S REPUBLIC OF CHINA JB/T Replacing JB/T Heavy low alloy steel castings 大型低合金钢铸件 Issued on: November 27, 2006 Implemented on: May 1, 2007 Issued by: National Development and Reform Commission

2 Contents Scope Nonnative References Ordering Requiretnents... I 4 Technical Requiren1ents Manufacturing Che1nical Co1nposition Mechanical Property Quality of the Cast Surface Shape and Size Tolerance Test Method and Test Rules Chemical Composition Analysis Mechanical Property Test Re-examination and Re-heat Tssreatment Surface Roughness Certificate of Conforn1ity Marking and Packaging... 6

3 Foreword This Standard replaces JB/T "Heavy Low Alloy Steel Casting". Compared with JB/T , this Standard has the following major changes: --Add ZG45Mn2, ZG30CMnMo and ZG15Cr1Mo material grades; --P and S content are reduced to be :s;0.030%; --C content of ZG20CMnMo in Table 1 chemical is changed from 0.12%~0.22% to 0.16%~0.22%; --The normalizing + tempering 22:55% of ZG40Mn2 in Table 2 "Mechanical Properties" is changed into 2::40%, add AKU2:30J; --In Table 2 "mechanical properties", hardness value of the ZG20Mn normalizing+ tempering 156HB is changed into 2:: 145HB, and at the same time, Refo Rm and A of the normalizing+ tempering state are modified; --In Table 2 "Mechanical Properties", ZG20CrMo and ZG42CrMO will be supplemented with indexes of the normalizing+ tempering state; --In Table 2 "Mechanical Properties", the ZG34CrMo grade is changed into ZG35Cr1Mo, and at the same time, the hardening and tempering state is added with Z, AKu and HB indexes, Rm is modified, the index of the normalizing + tempering state is also supplemented; --Add provisions on impact test in Table 2 (see 5.2.4); This Standard was proposed by China Machinery Industry Federation. This Standard is under the jurisdiction of Mechanical Industry Standardization Technical Committees on Heavy Casting Forging. This Standard was drafted by China National Erzhong Group Co. This Standard was prepared by XIAO Zhangyu and LV Youqing. All previous editions of this Standard are: -JB/T6402- l 992.

4 Heavy Low Alloy Steel Castings 1 Scope This national standard specifies general low alloy steel-cast ordering, technical requirements, test method, test rules, qualification, marking and packaging of heavy steel casting. This Standard is applicable to sand casting or castings of casting moulds with thermal conduction are similar to that of the sand mould. 2 Normative References The following standards contain provisions which, through reference in this text, constitute provisions of this Standard. For dated reference, subsequent amendments (excluding content of corrigenda) to, or revisions of, any of these publications do not apply. However, Parties to agreements based on this Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. For undated houses, the latest edition of the normative document referred to applies. GB/T 222 GB/T 223 Permissible Tolerances for Chemical Composition of Steel Products (All the parts) Methods for Chemical Analysis oflron, Steel and Alloy GB/T 228 Metallic Materials-Tensile Testing at Ambient Temperature (GB/T , eqv ISO 6892: 1998) GB/T : 1983) Metallic Materials-Charpy Notch Impact Test (GB/T , eqv ISO GB/T Metallic Materials-Brine II Hardness Test-Part 1: Test Method (GB/T , ISO : 1999, MOD) GB/T Roughness Comparison Specimens-Cast Surfaces (GB/ eqv ISO : 1979) GB/T JB/T Carbon Steel Castings for General Engineering Purpose The Heavy Mechanical General Techniques and Standards-Steel Castings JB/T Welding Steel Castings The Heavy Mechanical General Techniques and Standards- Repair JB/T 6397 The Heavy Carbon Structural Steel Forgings 3 Ordering Requirements The purchaser shall provide design sample to the supplier Grades and delivery states of the castings, other technical requirements are agreed upon by mutual agreement.

5 4 Technical Requirements 4.1 Manufacturing Smelting The steel for castings shall smelted by induction furnace, arc furnace, refined-smelting ladle furnace, or other adequate melting method confirmed by both the supplier and the purchaser Casting The casting method, excepted as otherwise stated herein, is solved by the supplier itself Heat Treatment The casting shall be heat-treated, unless otherwise specified, the supplier may make heat treatment according to the mechanical properties requirements Repair Welding The supplier may make repair welding for the casting defects according to provisions of JB/T Straightening The deformation of the casting may be eliminated by straightening, and the straightening is usually operated at room temperature, heat straightening may be adopted in particular cases. 4.2 Chemical composition The smelting chemical composition of the steel shall be in accordance with those specified in Table The mass fraction of the residual element content: Ni:S0.30%, Cr:S0.30%, Cu:S0.25%, Mo:S0.15%, V:S0.05% and the total residual elements' content is:sl.0%. If the purchaser has no demand, the residual element may not be used as the acceptance criteria When the product chemical compositions are analyzed according to the purchaser's requirements, the tolerance of the product chemical analysis shall be in accordance with GB/T Mechanical property The mechanical properties of the materials shall be in accordance with those specified in Table Quality of the cast surface The roughness of the casting surface shall be in accordance with the design or ordering contract, and it shall be as high as Ra l OOµm under general situation The surface of the casting shall not have defect influence its service and repair 2

6 5.2.4 For impact test, the average value of the three impacts on one group must be as high as the specified value, and only one could fail to be the specified value, but the value must be no less than 2/3 of the specified value. 5.3 Re-examination and Re-heat Treatment When the mechanical property test result is unqualified, double samples may be taken from the adjacent position of the unqualified test specimens, so as to make the test of the unqualified project. If any re-examination result is unqualified, the casting and standby test specimen may be used for the re-heat treatment The times for the re-heat treatment shall not be more than two times, but the tempering times are unlimited. 5.4 Surface roughness The inspection for the roughness of the cast surface complies with GB/T Certificate of Conformity When delivering the goods, the supplier must provide certificate of conformity to the purchaser, and the certificate includes the following content: a) Ordering contract number; b) Drawing number; c) Casting name; d) Materials grades; e) Standard number; f) Furnace number; g) Package number; h) Weight; i) Chemical composition analytic result; j) Mechanical property check result; k) Check result required by other contract. 7 Marking and Packaging 7.1 The supplier shall mark the supplier logo, contract number, manufacturing batch number and package number on the prominent positions of the casting. 7.2 The supplier shall pack the goods according to the condition and requirements for transportation. 6