Some standard content:
Mechanical Industry Standard of the People's Republic of China
Technical Conditions for Steel Castings for Fans
Subject Content and Scope of Application
This standard specifies the technical requirements, test methods and acceptance rules for steel castings for fans. JB/T6888--93
This standard applies to carbon steel, stainless acid-resistant steel and low-temperature steel castings for turbine compressors, blowers, ventilators, expanders and Roots blowers (including accessories).
2 Reference standards
GB150
GB223
GB228
GB229
GB231
Steel pressure vessels
Methods for chemical composition analysis of steel and alloys
Metal tensile test methods
Metal Charpy (U-notch) impact test methodsJinzhan Brinell hardness test methods
GB1223
Test method for intergranular corrosion tendency of stainless acid-resistant steelGB2100Technical conditions for stainless acid-resistant steel castingsGB.4159
Metal low-temperature Charpy impact test method
GB 6060. 1
Surface roughness comparison sample casting surface
GB6414Dimensional tolerances of castings
GB/T 11350
GB/T11351
GB/T 11352
Machining allowance of castings
Tolerance of casting weight
Casting carbon steel parts for general engineering
JB/T6890Technical conditions for repairing defects of carbon steel castings for fans 3 Technical requirements
For castings with special requirements, the order contract between the supply and demand parties shall be followed. 3.1 The grade of steel castings shall comply with the provisions of GB11352 and GB2100. 3.2 Production method and heat treatment
3.2.1 Steel castings can be made of electric furnace steel or open-hearth steel. For stainless acid-resistant steel and low-temperature steel, only electric furnace steel can be used. 3.2.2 Steel castings shall be shot blasted and delivered after stress relief treatment. 3.2.3 Steel castings that need to be stress-relieved after rough machining shall be clearly specified in the drawings or order contracts. 3.3 Mechanical properties and chemical composition
3.3.1 The chemical composition and mechanical properties of steel castings shall comply with the provisions of Table 1. 3.3.2 For steel castings with mechanical property requirements, at least three groups of test blocks (two of which are spare test blocks) shall be kept in each furnace and marked or cast with corresponding marks to check the mechanical properties of the materials. 3.4 Geometric shape, machining allowance, dimensional tolerance and weight tolerance 3.4.1 The outline of steel castings shall be clear, and the shuttle angle and fillet shall be distinct. Approved by the Ministry of Machinery Industry of the People's Republic of China on July 13, 1993 226
Implementation on July 1, 1994
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JB/T6888-93
14, GB6414 regulations (see Appendix A, Appendix B), weight 3.4.2 Machining allowance and dimensional tolerance shall comply with GB/T11350 (T tolerance shall comply with GB/T11351 MT14/12 grade regulations (the number above the slash is the upper deviation grade of weight tolerance, and the number below is the lower deviation grade).
3.4.3 The fillets without dimensions on the drawings are all R5. 3.4.4 The deviation of the volute and flow channel in the casing shall not exceed ±2% of the corresponding diameter size. 3.4.5 The misalignment of steel castings shall not exceed the wall thickness dimensional tolerance, and the misalignment box shall be rounded (flat) and smoothly transitioned after cleaning. 3.5 Surface quality
3.5.1 The surface roughness of the flow channel of the steel casting shall meet the requirements of R.50 of GB6060.1 for more than 50% of the surface, and R.100 for the rest of the surface. The surface roughness of the rest of the steel casting shall not exceed R.100. 3.5.2 The gates, risers, subsidies and process ties on the non-processed surface shall be removed before heat treatment. The residual height after cutting shall not exceed the requirements of Table 2.
Table 2 Residual height of gates, risers, subsidies and process reinforcements on non-machined surfaces after cutting Grommets, risers, subsidies
Maximum size of reinforcement
Residual height
100
+3
2
>100～~200
+
200~350
+
>350～500
4
>500~750
+
mm
>750
3.5.3 The roots of gates, risers, subsidies, process reinforcements and flash on non-machined surfaces after cutting shall have a round (flat) smooth transition with the casting surface after cleaning.
3.5.4 The scale, chill and core bone on the inner and outer surfaces of steel castings shall be cleaned up. 3.6 Defects
3.6.1 Steel castings are not allowed to have cracks, shrinkage and cold shut defects that affect the use of castings. Otherwise, they should be completely removed. If the wall thickness exceeds the allowable deviation of the size after the defects are removed, welding should be performed. 3.6.2 The degree of shrinkage, pores, sand holes and slag inclusion defects on the non-machined surface of steel castings shall not exceed the following provisions: 3.6.2.1 The area, number, distance and depth of defects: a.
b.
1%,
c.
d.
The area of ??a single defect shall not be greater than 0.5cm2; there shall be no more than two defects per 100cm2 plane, and the sum of the defect areas on the entire plane shall not exceed the total area of ??the plane. The distance between two defects shall not be less than 6 times the maximum diameter of the defect; the relationship between the depth of the defect and the wall thickness of the casting shall comply with the provisions of Table 3. Table 3
Thickness of casting
12
>12～20
≥2032
>32～50
>50～80
>80
Defect depth
2
3
A
6
8
10
mm
3.6.2.2 For non-penetrating pinhole defects with a diameter less than 1.5mm, the pinhole spacing shall not be less than 6mm, and there shall be no more than 4 pinholes per 1000cm2 plane. The total unit area of ??the defect shall be less than 10% of the total area of ??the region where it is located. 3.6.3 The depth of casting defects on the machined surface of steel castings shall not exceed the hand of the machining allowance. 3
228
3.7 Repair welding
JB/T 6888-93
3.7.1 Repair welding of defects in carbon steel castings shall comply with the provisions of JB/T6890 "Technical Conditions for Repair Welding of Defects in Carbon Steel Castings for Fans". 3.7.2. For repair welding of stainless acid-resistant steel and low-temperature steel castings, the welding process of the steel type should be considered. 3.8 Stainless acid-resistant steel castings should be subjected to intergranular corrosion test in accordance with GB1223 according to the requirements of the drawing and order contract. 3.9 For cast steel parts under pressure such as casings, a 1.5 times working pressure test should be carried out after rough machining, and no leakage should be allowed for 30 minutes. 4 Acceptance rules for test methods
4.1 Chemical analysis
4.1.1 Chemical analysis test blocks should be poured from the molten steel in the ladle, and test blocks poured in the middle of the pouring should be used. When using drilling for chemical analysis, the sample should be taken from a position less than 6 mm from the surface of the test block. 4.1.2 Chemical analysis should be carried out for each furnace, and the results should comply with the requirements in Table 1. 4.1.3 The chemical composition analysis method of steel castings should comply with the regulations of GB223. 4.2 Mechanical properties
4.2.1 The mechanical properties test block should be of the same furnace number as the casting it represents, and the same heat treatment heat treatment. 4.2.2 The size specifications and pouring method of the test block should comply with the regulations of GB11352. 4.2.3 For castings with body test blocks, the size specifications and location of the body test blocks shall be specified by the part drawing or process drawing. 4.2.4 When the sample is insufficient, it can be cut from the casting after negotiation, but it must be ensured that there is sufficient processing allowance for the sample. 4.2.5 The tensile test shall be carried out in accordance with the provisions of GB228, the low overflow impact test shall be carried out in accordance with the provisions of GB4159, and the hardness test shall be carried out in accordance with the provisions of GB231. The results should comply with the requirements in Table 1. 4.2.6 If the sample is found to have casting or machining defects, the test results will be invalid and the sample should be re-sampled for testing. 4.2,7 When the collective results of the mechanical property test do not meet the requirements, double the number of samples are allowed to be retested for the unqualified items. Even if one sample fails, the castings it represents will be continued. The spare test block is subjected to another heat treatment and retested. If the test results are still unsatisfactory, the castings represented by the test specimens shall be reported. 4.3 The intergranular corrosion test shall be carried out in accordance with the provisions of GB1223. 4.4 For pressure cast steel parts such as casings, a hydraulic test should be carried out after rough construction. The pressure test standards shall refer to the provisions of the test part of GB150 for acceptance.
4.5 Shape dimensions, wall thickness deviations and weight deviations shall be accepted according to the provisions of Article 3.4. 4.6 Use graphic measurements and conventional measuring tools to check the appearance quality. 4.7 Carry out non-destructive inspection in accordance with the drawings or ordering contract, using magnetic particle inspection method for steel castings and coloring method for austenitic stainless steel. 4.8 For castings that require ultrasonic flaw testing or radiographic flaw testing, the inspection locations and acceptance standards should be clearly specified in the drawing or order contract, and acceptance should be carried out according to the specified standards.
5 Marks and Product Certificates
5.1 The delivery castings should have the following marks:
a.
b.
c.||tt ||Use a steel stamp to mark the part drawing number on the white-painted position; use a steel stamp to mark or cast a mark (cast the student number), and its location should be in an obvious place on the non-processed surface or as specified in the drawing: use a steel stamp to mark the inspection qualification mark .
5.2 Each batch of delivered castings should have a product certificate, the content of which is as follows: a.
b.
&
Ordering contract number (when there is an ordering contract) Adopted); part drawing number;
material grade and heat treatment status:
melting furnace number:
chemical composition and mechanical properties and special test reports as specified in the part drawing or order contract; 229
f． Copy of repair welding record of pressure parts such as casing: .
Acceptance standard number.
JB/T6888—93
5.3 The product certificate shall have the seal of the person in charge of the technical inspection department of the manufacturer and the seal of the inspection department. Appendix A
Casting machining allowances used in conjunction with casting dimensional tolerances (GB/T11350) (supplement)
Dimensional tolerance levels
CT
Machining allowances Level
MA
Basic size
100
>100～160
>160～250
>250～400||tt ||>400～630
>630～1 000
14
Machining allowance
8.5
6.0
10|| tt||7.0
13
9.0
15
11
18
13
20||tt| |15
Dimensional tolerance level
CT
Machining allowance level
MA
Basic size
>1000～1 600|| tt||>1600~2500
>2 500~4 000
>4 000-6 300
≥6 300-~10 000
14||tt ||J
Machining allowance
23
17
25
19
29
22||tt ||34
25
38
28
Note: There are two machining allowance values ??in each column in the table. The above values ??are based on one side. The allowance value for single-sided machining; the following value is the machining allowance value for each side when double-sided machining is performed,
230
The basic size of castings
is greater than ||tt| |10
16
25
40
63
100
160
250
400
630
1000
1600
2500
4000
6300
to
10|| tt||16
25
40
63
100
160
250
400||tt| |630
1000
1600
2500
4000
6300
10000
3
0.18
0.20
Gate 22
0.24
0.26
0.28
0.30
0.34
0.10| |tt||0,26
0.28
0.30
0.32
0.36
.40
0.44
0.50
56
0.64
JB/T6888-93
Appendix B
Casting dimensional tolerance values ??(GB6414-86) (supplement)||tt ||public
6
0.36
0.38
Q,42
0.46
0.50
0.56||tt ||0.62
0.70
0.78
0.90
1.0
Q.52
0.54
0.58||tt ||0.64
0.70
0.78
0.88
1.0
1.1
1.4
ftt
0. 74
0.78
0.82
0.90
1.0
1.1
1.2
. 6||tt| |2.0
2, 2
8
.
1,4
2.8
difference
etc.|| tt||1.0
7.0
10
11
level
12
14
16||tt| |CT
Note: There is no specified tolerance value for CT1 and (T2), which are reserved for meters that may require more precise tolerances. 23
28
32
30
35
40
② When CT13 and CT16 are less than or equal to the basic size of 16mm casting.The tolerance value needs to be marked separately and can be increased by 2 to 3 levels. Additional explanation:
This standard is proposed by the National Technical Committee for Fan Standardization. Who is responsible for drafting and reporting this standard to Shenyang Blower Research Institute: the main drafters of this standard; Yan Lizheng, Chen Mingliang, Tian Suwen, and He Jitong. 25
33
38
44
50
12
20
22
25| |tt||28
32
37
49
56
64
231
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