JB/T 7946.1-1999 This standard is a revision of JB/T 7946.1-95 "Modification of Cast Aluminum-Silicon Alloys". During the revision, only editorial changes were made according to relevant regulations, and the main technical content remained unchanged. This standard specifies the classification principles and rating methods for the modification of cast aluminum-silicon alloys. This standard is applicable to the evaluation of the metallographic structure of cast aluminum-silicon alloys modified by sodium and phosphorus. JB/T 7946.1-1999 Modification of Cast Aluminum-Silicon Alloys JB/T7946.1-1999 Standard download decompression password: www.bzxz.net

ICS77.120.10
Machinery Industry Standard of the People's Republic of China
JB/T7946.1-1999
Metallography of castaluminium alloysCast aluminium-silicon alloysModification1999-06-24Promulgated
National Bureau of Machinery Industry
Implementation on 2000-01-01
JB/T7946.1-1999
This standard is a revision of JB/T7946.1-95 "Modification of cast aluminium-silicon alloys". During the revision, editorial changes were made to the original standard, and the main technical content remained unchanged.
This standard replaces JB/T
7946.1—95
This standard is proposed and managed by the National Technical Committee for Casting Standardization. The drafting units of this standard are Shenyang Foundry and Shenyang Foundry Research Institute. 1
1 Scope
Mechanical Industry Standard of the People's Republic of China
Metallography of cast aluminium alloys
Modified cast aluminium-silicon alloys
Metallography of cast aluminium alloysCastaluminium-siliconalloys-Modificatian This standard specifies the classification principles and rating methods for modified cast aluminium-silicon alloys. This standard is applicable to the evaluation of the metallographic structure of cast aluminium-silicon alloys modified by sodium and phosphorus. 2 Casting aluminum silicon alloy sodium modification
2.1 Cutting and preparation of samples
JB/T7946.1-1999
Replaces B/T7946.1-95
2.1.1 Metallographic samples are usually cut from the single cast tensile test bar of the furnace. Metallographic samples of important castings should be cut from the attached cast test bar of the casting or according to the provisions of the technical documents
2.1.2 The metallographic sample is mechanically polished after rough grinding and fine grinding with metallographic sandpaper, and manual fine polishing can be performed if necessary. The polished metallographic sample is etched with Q.5% hydrofluoric acid aqueous solution at room temperature for 5~10S. 2.1.3
2.1.4 In the process of cutting and preparing the metallographic sample, it should be ensured that the structure does not change. 2.2 Microscopic Examination
The metallographic structure of the cast aluminum-silicon alloy modified by sodium is evaluated by an optical microscope, and the magnification is 200 times. 2.2. 1
When performing microscopic examination, the entire inspection surface should be viewed first, and then the evaluation should be carried out according to the corresponding level diagram of most fields of view. 2.2.2
The sodium modification of cast aluminum-silicon alloy is divided into six levels: unmodified, insufficiently modified, normal modified, degraded, slightly over-modified and severely over-modified.
For the sodium modification of cast aluminum-silicon alloy, the classification of metallographic structure is shown in Table 1. Table 1
Level Name
Unmodified
Insufficiently modified
Normal modified
Degraded
Slightly over-modified
Severely over-modified
Microstructural Characteristics
Eutectoid silicon is long needle-shaped and has no regular distribution. There may be α dendrites or a small amount of blocky primary silicon. The dendrites and eutectics are evenly distributed. Some eutectic silicon is short rod-shaped and some is needle-shaped. The α dendrites and eutectics are evenly distributed. The eutectic silicon is point-shaped or worm-shaped. The distribution of a dendrites and eutectics is not evenly distributed. The eutectic silicon becomes thicker, some are short rod-shaped and some are needle-shaped. The distribution of a dendrites and eutectics is basically even, but linear α bands appear in some eutectics. The distribution of α dendrites and eutectics is very uneven, and coarse metamorphic bands appear (wavy a bands appear in fine eutectics, and there are many coarse eutectic silicon in the bands). Approved by the State Bureau of Machinery Industry on June 24, 1999. Drawing No.
Implementation on January 1, 2000www.bzxz.net
Figure 1 No metamorphism
Figure 3 Normal metamorphism
JB/T 7946.1—1999
Figure 2 Insufficient modification
Degradation
Figure 5 Mild overmodification
3 Cast aluminum silicon eutectic alloy phosphorus modification
Sample cutting and preparation
JB/T 7946.1-1999
Figure 6 Severe overmodification
3.1.1 Metallographic samples are usually cut from the single cast tensile test bars of the furnace. Metallographic samples of important castings should be cut from the attached cast test bars of the castings or according to the provisions of the technical documents.
3.1.2 The metallographic samples are mechanically polished after rough and fine grinding with metallographic sandpaper, and manual fine polishing can be performed if necessary. 3.1.3 The polished metallographic specimen is etched with 0.5% hydrofluoric acid aqueous solution or a mixed acid aqueous solution of 0.5mL hydrofluoric acid, 15mL hydrochloric acid, 2.5mL nitric acid and 95.5mL water at room temperature. 3.1.4 In the process of cutting and preparing the metallographic specimen, it should be ensured that the metallographic structure does not change. 3.2 Microscopic examination
3.2.1 The metallographic structure of the cast aluminum-silicon eutectic alloy modified by phosphorus is evaluated by an optical microscope, and the magnification is 100 times. 3.2.2
When performing microscopic examination, the entire inspected surface should be viewed first, and then the evaluation should be carried out according to the corresponding level diagram of most fields of view. The phosphorus modification of the cast aluminum-silicon eutectic alloy is divided into four levels: unmodified, well modified, normal modified and insufficient modified. The classification description of phosphorus modification of the cast aluminum-silicon eutectic alloy is shown in Table 2. Table 2
Grade Name
Not metamorphosed
Well metamorphosed
Normal metamorphosed
Under metamorphosed
No obvious α dendrites, eutectic silicon is needle-shaped, unevenly distributed
No a dendrites, eutectic silicon is short flakes, evenly distributed, primary silicon is small blocks with a small amount of α dendrites, eutectic silicon is needle-shaped, unevenly distributed. Primary silicon is a small block with developed α dendrites, obvious hypoeutectic organization Figure No.
Figure 7Not metamorphosed
Figure 9Normal metamorphosed
JB/T 7946.1-1999
Good deterioration
Insufficient deterioration
Mechanical industry standard
Metallography of cast aluminum alloy
Deterioration of cast aluminum silicon alloy
JB/T7946.1-1999
Published and distributed by the Machinery Standardization Research Institute of the Ministry of Machinery Industry Printed by the Machinery Standardization Research Institute of the Ministry of Machinery Industry (No. 2 Shouti South Road, Beijing
Postal code 100044)
Format 880×1230
Edition X, XX, 19XX
Printing number 1-XXX
Printing sheet XIX Number of words XXX,XXX
Xth printing, XX, 19XX
Price XXXXX Yuan
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