This standard applies to carbon steel castings with good weldability for general engineering structures. GB 7659-1987 Carbon steel castings for welded structures GB7659-1987 Standard download decompression password: www.bzxz.net

UDC621.741.4:621.791
National Standard of the People's Republic of China
GB 7659-87
Carbon steel castings suitable for welded structure1987—04-17Promulgated
National Bureau of Standards
Implementation on 1987-12-01
WNational Standard of the People's Republic of China
Carbon steel castings suitable for welded structureThis standard applies to carbon steel castings (hereinafter referred to as castings) with good weldability for general engineering structures. Grade
UdC 621.741.4
：621.791
GR 765987
This standard includes three cast steel grades: ZG200-400H, ZG230-450H, and ZG275-485H. The grade notation method shall comply with the provisions of GB561385 "Method for indicating cast steel grades". The "H" at the end of the grade is the first letter of the Chinese pinyin of the word welding, indicating welding steel.
2 Technical requirements
2.1 Chemical analysis
The chemical composition of each grade of cast steel shall comply with the provisions of Table 1. For every 0.01% reduction in the actual carbon content from the upper limit of carbon in the table, the actual manganese content is allowed to exceed the upper limit of manganese in the table by 0.04%, but the total excess shall not exceed 0.20%. Table 1 Chemical composition
ZG 20l - 40H
ZG 230 - 450H
ZG 275-485H
Heart, called
2.2 Manufacturing
The smelting method and casting process of steel shall be determined by the supplier. 2.2.1
Not more than
Castings shall be cleaned and finished. Castings after cleaning and finishing shall comply with the provisions of 2.5.1 and 2.5.2. 2.2.2
Castings shall be heat treated. The heat treatment process shall be determined by the supplier. Common heat treatment types are: 2.2.3
Normalizing!
Normalizing and tempering (tempering temperature not less than 550℃) For castings that need repair welding, repair welding and inspection can be carried out according to the supplier's standards. If the purchaser has other requirements, it shall be carried out according to the provisions of the contract.
2.3 Shape, size and weight
2.3.1 The shape, size and weight of the casting shall comply with the requirements of the drawing or contract. The dimensional tolerance of the casting shall comply with GB6414-86 "Casting Dimension Tolerance" or the requirements of the drawing or contract. The weight tolerance of the casting shall comply with the requirements of the drawing or contract. 2. Mechanical properties of the series
Approved by the National Bureau of Standards 19B-04-17
Implementation in 198-12-01
WGB785987
The mechanical properties of each brand system meet the requirements of Table 2. The impact performance index is the average value of the test results of the gram impact specimens. Only one specimen is allowed to have a test result of the minimum index. But it shall not be less than two-thirds of the index. Table 2 Primary performance
Vpa (kgr/mm')
ZG 200-400H
ZG230-45n1
7.G 275 - 486H
(kgf.m/cm\)
Note: Impact performance, instrument loss party does not have the total ratio (Y-type notch) minus plus\conditions, it is allowed to temporarily follow the impact performance value of the summer book (U plastic notch) test bank "ku delivery
2.5 Quality
2.5.1 The surface roughness of the casting shall comply with the provisions of G86060.1-85 "Surface Roughness Comparison Sample Casting Table". 2.5.2 There should be no defects such as cracks, holes, cold shuts and sand on the casting that affect its use, and the oxidized iron scale should be removed. 2.5.3 When the purchaser requires non-destructive testing of the casting, the inspection The test location and method shall be specified in the drawing or contract.
3 Test method
3.1 Chemical composition analysis
The sample for chemical analysis shall be prepared in accordance with the provisions of GB222--84 "Sampling method for chemical analysis of steel and allowable deviation of chemical composition of products". Chemical analysis shall be carried out in accordance with the provisions of GB223-81 "Chemical analysis method for steel and alloys". 3.2 Mechanical performance test
3.2.1 Tension and punching test specimens shall be prepared on test blocks for mechanical properties. 3.2.1.1 Shape, size, method and cutting position of test blocks It shall comply with the provisions of GB6676-85 (Generally speaking, it is a steel for process use). However, the casting part of the test block is determined by the supplier. If the purchaser has special requirements, the supply and demand parties shall negotiate. 3.2.1.2 The test block and the batch of castings it represents (see 4.2) shall have the same furnace number and the same steel grade. The test pieces can be heat treated in the same furnace. 3.2.2 When the number of test blocks is not fixed, it is allowed to take samples from the missing pieces in the batch for testing. The sampling position is determined by the supplier, and the performance indicators are negotiated by the supply and demand parties.
3.2.3 The tensile test specimen shall be a short proportional specimen with a diameter of 10mm (specimen number R4) in accordance with GB6397-《Metal Tensile Test Specimen》11. The tensile test shall be carried out in accordance with the provisions of GB22876 "Metal Tensile Test Method". 3.2.4 The impact test shall be carried out in accordance with the provisions of GB2106-80 "Metal Charpy (V-notch) Punch Test Method" or temporarily in accordance with GB229-81 "Metal Charpy (U-notch) Impact Test Method". The impact test specimen shall be a standard specimen. Inspection rules
4.1 Inspection and acceptance
The inspection and acceptance of castings shall be carried out by the technical inspection department of the supplier. The purchaser has the right to conduct a review in accordance with the provisions of the contracting company of this standard. 4.2 Castings with the same cast steel grade, the same smelting furnace number and the same heat treatment shall be considered as a batch. 2
WGB 7659-87
4.2.1 When the capacity of the steelmaking furnace is less than 50 kg, under the condition of stable smelting process and small chemical composition fluctuation, castings cast by the same grade of cast steel smelted in the same steelmaking furnace in the region are allowed to be treated as castings with the same smelting furnace number (only applicable to mechanical property inspection)
4.2.2 When the capacity of the heat treatment furnace is small, under the condition of stable heat treatment process and stable heat treatment quality, castings heat treated in the same type of heat treatment furnace are allowed to be treated as castings with heat treatment. 4. Sampling quantity
4.3.1 Take one chemical analysis sample for each smelting furnace number. 4.3.2 Take one tensile test sample and one impact test sample for each batch of castings. .4 Evaluation and re-test
4.4.1 The chemical analysis results are qualified when they meet the requirements of 2.1. 4.4.2 The mechanical properties test results are qualified when they meet the requirements of 2.1. If they do not meet the requirements of 2.4, the unqualified tests can be retested. The retest results are qualified when they meet the requirements of 4.4.3 and 4.1.4. 4.4.3 For the retest of the tensile test, two specimens shall be taken from the same batch of test blocks, and the test results of each specimen shall meet the requirements of 2.4. 4.4.4 For the retest of the impact test, three specimens shall be taken from the same batch of test blocks, and the test results shall meet the requirements of 2.4, and the average of the test results of the six specimens including the initial test shall meet the requirements of Table 2: 4.1.5 When the mechanical properties test or retest fails, it is allowed to reheat treat the batch of castings and test blocks and then retest. Without the final consent of the purchaser. The reheat treatment shall not exceed two times (the number of tempering is unlimited) 4.4.6 When there are structural defects on the cross section of the mechanical properties test specimen, or the test operation is wrong, the test result is invalid. Another sample should be taken from the same batch of test blocks for testing.
5 Marking
5.1 The casting should be cast or punched with a mark. The finished product should be marked with the seal of the supplier's technical inspection department and with a stamped paint. 5.1.1 After consultation between the supplier and the buyer, small castings shall be marked by batch. The mark should be punched on the label of each batch of castings. 5.2 The finished casting should have a certificate, the contents of which include: a. Name*
b, order contract number,
c: cast steel brand number, melting furnace number, batch number: d. Various inspection results;
Inspection results of special requirements specified in the drawing or contract. W.GB 7659—B7
Appendix A
Regulation on Carbon Equivalent
(Supplement)
When the purchaser has carbon equivalent (CE) requirements, the magnetic equivalent of each grade of cast steel shall comply with the provisions of the following table. A.1
Carbon Equivalent
ZG200-400H
ZG230-450H
ZG275-485H
A,2 Carbon content is calculated according to the following formula:
CE(%) -C+
Cr+Mo+Www.bzxZ.net
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Where C, Mn, Cr, Mo, Ni, V, Cu are the content of each element (%). WGB7659-87
Supplementary provisions on mechanical properties
(Supplementary)
B.1 The mechanical properties of each grade of cast steel in Table 211 of this standard are applicable to castings with a thickness not exceeding 100mm. B.2 When the wall thickness of the casting exceeds 100mm, the yield strength in Table 2 can be used for design. B.3 When it is necessary to take samples from castings that have been heat treated or from large test blocks representing castings, the performance indicators shall be negotiated by both the supply and demand parties. Additional notes,
This standard was proposed by China Shipbuilding Industry Corporation and is under the jurisdiction of Shenyang Foundry Research Institute. This standard was drafted by the Luoyang Ship Material Research Institute of China State Shipbuilding Corporation, with participation from Jiangnan Shipyard, Beijing Cheng Machinery Steel Plant, Shanghai Jiaotong University and Dalian Shipyard. The main drafters of this standard are Ji Jialong, Mo Weijie, Cheng Keqin, Liao Jiaheng, Yao Shoushan and Chen Bingli.
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