Some standard content:
National Standard of the People's Republic of China
Corrosion resistant high silicon iron castings
Corrosion resistant high silicon iron castingsThis standard applies to high silicon corrosion resistant iron castings containing 10.00%~18.00% silicon. Grade
UDC 621.741.3
: 669.018.8
GB8491--87
The grades in this standard comply with the provisions of GB5612--85 "Method for Expressing Cast Iron Grades" and are divided into five grades: STSi11Cn2CrR, STSi15R, STSi15Mo3R, STSi15Cr4R, and STSi17R. 2 Technical requirements
2.1 Chemical composition is used as the acceptance basis for high silicon corrosion resistant cast iron. It should comply with the provisions of Table 1. 2.2 The mechanical properties of high silicon corrosion resistant cast iron are generally not used as the acceptance basis. If the purchaser has requirements, its mechanical properties shall comply with the provisions of Table 2.
High silicon corrosion resistant cast iron is a relatively brittle metal material. There should be no sharp angles and sharp cross-sectional transitions in the structural design of its castings. 2.3
The gates, risers, burrs, fleshy parts, scars and sand adhesion on the castings shall be removed, and the surface shall be smooth and bright. 2.4
The surface roughness of the castings shall be inspected in accordance with the provisions of GB6060.1-85 "Surface roughness comparison sample casting surface" and the grade agreed upon by the supply and demand parties.
2.6 The dimensional tolerance of the castings shall comply with the provisions of GB6414-86 "Dimensional tolerance of castings". Table 1 Chemical composition of high silicon corrosion resistant cast iron
Maximum value
STSi1Cu2CrR
STSi15R
STSi15Mo3R
STSi15Cr4R
STSi17R
Approved by National Bureau of Standards on December 28, 1987
Maximum value
Maximum value
Minutes, %
R Residue
Maximum catalysis
Implementation on August 1, 1988
STSi11Cu2CrR
STSi15R
STSi15Mo3R
STSi15Cr4R
STSi17R
Big! 0
Maximum length of casting
To 120
Pouring position of casting
Maximum height
120
GB8491—87
Table 2 Mechanical properties of high silicon corrosion resistant cast iron
Minimum bending strength, αw
N/mm2(kgl/mm2)
190(19.40)
140 (14.30)
130(13.30)
130(13.30)
130(13.30)
Minimum deflection
Table 3 Mechanical allowance of castings
Maximum hardness
GB8491--87
2.7 The weight deviation of castings shall comply with the relevant provisions on the drawings or the technical requirements of the order. 2.8 The machining allowance of castings shall comply with the provisions of Table 3. 2.9 If the purchaser has no special requirements, the heat treatment of the casting to eliminate internal stress shall be carried out according to the following specifications: the casting is boxed in a red-hot state, and all mechanical resistance that hinders the free contraction of the casting is quickly eliminated, the pouring gate is cleared, and the red-hot casting is directly placed in a pre-heated heat treatment furnace above 600℃, and then the casting is slowly heated to 750-850℃ (the lifting speed is 45℃/h). According to the structural dimensions and wall thickness of the casting, it is kept in this temperature range for 2-4 hours, and the casting is taken out of the furnace when the furnace temperature drops below 100℃.
The casting should not have casting defects that reduce strength and damage the appearance of the product. The allowable defect range of the casting is in accordance with the provisions of Table 4. The defects that can be repaired and their repair methods shall be determined by the manufacturer or the supply and demand parties through negotiation. 2.10
When the casting needs to be subjected to a water pressure test, it shall be specified in the drawings or ordering technical documents. 302
GB 8491-87
000~009
.00002
3 Test methods
3.1 Chemical analysis
GB 8491-87
The arbitration analysis of the chemical composition of high silicon corrosion resistant cast iron shall be carried out in accordance with the provisions of GB223--84 "Chemical analysis methods for steel and alloys". The sampling method for chemical analysis shall be carried out in accordance with the provisions of GB222-84 "Sampling method for chemical analysis of steel and allowable deviation of chemical composition of finished products". Note: Hydrofluoric acid is used as solvent for analyzing silicon.
3.2 Test bars
Bending and deflection tests use single cast test bars with a diameter of 30mm and a length of 340mm. The hardness test bars are taken from the bending test bars. Single casting test bar is used for casting the same batch of molten iron (not the first and last package) in the wet mold or ten-mold, and vertical pouring. In the same mold, several test bars can be poured at the same time, and the distance between the test bars should not be less than 50mm. 3.3 Mechanical property testwwW.bzxz.Net
3.3.1 Bending and deflection test shall be carried out in accordance with the provisions of GB977-84 "Metallic Rockwell Hardness Test Method". 3.3.2 Rockwell hardness test shall be carried out in accordance with the provisions of GB230-83 "Metallic Rockwell Hardness Test Method". 3.4 Water pressure test
For parts subjected to hydraulic pressure, water pressure test can be carried out with clean water at room temperature, and the test pressure shall be 1.5 times of the working pressure, and the pressure holding time shall be not less than 10 minutes.
4 Inspection rules
4.1 Batch division
For cast iron, under the specified melting process and fixed charge, each batch of castings is limited to 2000kg, as a batch, and the sampling times are taken.
4.2 Number of tests and furnace number
4.2.1 Each batch should be subjected to at least one group (three bars) of bending test and one chemical composition analysis. 4.2.2 In order to ensure that the furnaces of castings and test bars are alternated, clear furnace numbers should be cast on the non-important surfaces of castings and test bars. 4.3 Evaluation of inspection results
4.3.1 When inspecting the bending strength, first use a group (three bars) of test bars for testing. If two bars meet the requirements, they are qualified. If only one bar meets the requirements in the qualified test results, another group (three bars) of test bars should be taken from the same batch of test bars. Repeat the test. If two test bars meet the test results, the casting is still qualified. Otherwise, the batch of castings is unqualified. 4.3.2 If the test bar fails the test due to the following reasons, the test is invalid. a. There are casting defects on the surface of the test bar,
b. There are casting defects on the fracture of the test bar:
The test bar is improperly installed on the testing machine or the testing machine is improperly operated. C.
4.4 Casting quality and geometric shape
4.4.1 The appearance quality of the casting should be checked piece by piece, and its surface roughness should be sampled. 4.4.2 The size and geometric shape of the first batch of castings and important castings should be checked piece by piece, and general castings can be sampled. The sampling method is determined by negotiation between the supply and demand parties.
4.4.3 For the pressure-bearing parts that require water pressure test, they should be inspected piece by piece. During the inspection, if the casting leaks or sweats during the pressure duration, the casting is unqualified. 5. Certificate, marking, packaging, transportation and storage 5.1 Each batch of castings shall be accompanied by a certificate of conformity with this standard, the contents of which shall include: a. Manufacturer's name; b. Drawing number and part number, c. High silicon corrosion resistant cast iron grade, GB849187 inspection results (including the word "qualified" or test results); e. This standard number. 5.2 Qualified castings shall have the mark of the manufacturer's technical inspection department. 5.3 Castings may be wrapped with straw ropes or straw bags before leaving the factory, or they may be packed in packaging boxes. Castings shall be protected from collision and hammer damage during transportation, storage, installation and use. 5.4 STSil1Cu2CrR STSi15R.STSi17R
STSi15Mo 3R
STSi15Cr 4R
Additional notes:
GB 8491-87
Appendix A
Performance, applicable conditions and application examples of high silicon corrosion resistant cast iron parts (reference parts)
Performance and applicable conditions
It has good mechanical properties and can be produced by general mechanical processing methods. It has relatively stable corrosion resistance in sulfuric acid with a concentration greater than or equal to 10%, nitric acid with a concentration less than or equal to 46%, or mixed acid composed of the above two media, sulfuric acid with a concentration greater than or equal to 70% plus fluorine, benzene, benzenesulfonic acid and other media, but no sharp alternating load, impact load and temperature mutation are allowed.
It has good corrosion resistance in oxidizing acid (for example: nitric acid, sulfuric acid, chromic acid, etc. of various temperatures and concentrations), various organic acids and series of salt solution media, but it is not corrosion resistant in halogen acid, salt solution (such as hydrofluoric acid and fluoride, etc.) and strong alkali solution. No sharp alternating load, impact load and temperature mutation are allowed.
In sulfuric acid, nitric acid, hydrochloric acid of various concentrations and overflows, in alkaline aqueous solution and brine solution, when the temperature difference of various parts on the same casting is not more than 30℃, it has particularly high corrosion resistance without dynamic load, alternating load and pulse load, has excellent electrochemical corrosion resistance, and has corrosion resistance with improved oxidation resistance conditions. The chromium in high silicon chromium cast iron can improve its passivation and pitting breakdown potential, but no sharp alternating load and temperature mutation are allowed. This standard was proposed by the State Machinery Industry Committee and is under the jurisdiction of Shenyang Foundry Research Institute. Dalian Acid Pump Factory was responsible for drafting this standard, and Dalian Institute of Technology participated in the drafting. The main drafters of this standard are Yu Yong, Shao Youquan, Xiang Li, Shang Zhanshan, Li Longsheng, and Qin Zirui. 30 Application examples Horizontal centrifuges, submersible pumps, valves, cocks, tower tanks, cooling drain pipes, elbows, etc. Chemical equipment and parts, etc. Various centrifugal pumps, valves, cocks, pipe fittings, tower tanks, low-pressure vessels and various non-standard parts. In the cathode expansion system of impressed current, rat parts are used to assist anode castings.
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