JB/T 7946.4-1999 JB/T 7946.4-1999 Grain size of cast aluminum-copper alloy JB/T7946.4-1999 Standard download decompression password: www.bzxz.net

JB/T7946.4—1999
This standard is a revision of JB/T7946.4-95 "Revision of Cast Aluminium Alloys". The main technical contents remain unchanged.
This standard replaces JB/T7946.4--95 from the date of implementation. Editorial revisions were made to the original standard during the revision. This standard was 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. 388
1 Scope
Metallograph of cast aluminium alloysCast aluminium-copper alloys--Grain size This standard specifies the classification principles and rating methods for the grain size of cast aluminium-copper alloys. This standard is applicable to the evaluation of the grain size of cast aluminum-copper alloys. 2. Cutting and preparation of samples
JB/T 7946.4---1999
Replaces JB/T7946.4-95
2.1 Metallographic samples are usually cut from tensile test bars. If there are special requirements, they can be cut according to the provisions of the technical documents. 2.2 The metallographic samples are mechanically polished after rough grinding and fine grinding with metallographic sandpaper. If necessary, they can be finely polished manually or electrolytically polished. 2.3 The polished metallographic samples are etched with 0.5% hydrofluoric acid aqueous solution or a mixed acid aqueous solution of 0.5ml hydrofluoric acid, 1.5mL hydrochloric acid, 2.5mL nitric acid, and 95.5mL water at room temperature. 2.4 Heating and deformation are not allowed during the cutting and preparation of metallographic samples. 3 Microscopic examination
3.1 Use an optical microscope to evaluate the grain size of cast aluminum-copper alloys. The magnification is 100 times. 3.2 During microscopic inspection, the entire surface to be inspected should be viewed first, and then the evaluation should be carried out according to the corresponding grade diagram of most fields of view. 3.3 In the same sample, if there are grains of different sizes, the percentage of each type of grain should be estimated and noted in the report. 3.4 The grain size of cast copper alloy is divided into eight grades. The description of the grades is shown in Table 1. Table 1
Number of grains per unit area
pieces/mm2
Approved by the State Bureau of Machinery Industry on June 24, 1999 Number of grains per area with field diameter ±70mm
(0.385mm*)）
(1.54mm2)）
Implementation on January 1, 2000www.bzxz.net
Figure 525
JB/T 7946.4-1999
Figure 23
Figure 650
Figure 7100
JB/T 7946.4--1999
Figure 8200
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