Your comments will receive careful consideration at a meeting of the responsible technical committee, which you may attend. Salts dissolved in HCl with minimum of hot water. Immerse specimen in solution which may be heated or not depending upon alloy. The molybdate etch listed in Table 7 is used in the removal of worked metal and also to reveal the structure of lead of low-alloy content. Best results are obtained with a ground surface. Mix with strongest H2O2 available to minimize water content.
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A good test for the presence of cold work, especially in coarsegrained samples, is the appearance of twinning after etching. In this case, other methods such as dye penetrant methods may be more desirable.
After rinsing with hot water, blow the specimen dry with compressed air. The specimen or specimens should be placed in a tray of stainless steel screen or on some non-reactive support.
The solution should be kept in an ice bath during this operation. If you feel that your comments have not received a fair hearing you should make your aztm known to the ASTM Committee on Standards, at the address shown below. If the specimen is then given light regrinding to remove the rough etched surface, the second etch will provide good results. Replaces portions of Method E 3. An effort should astm e340 made to wet the entire surface as soon as possible.
Details of the procedure not discussed here are covered in the sections for the various metals and their alloys. Electrolytic, specimen moves past a cathode bar, 30 to 40 A per inch of specimen width, rinse, brush, and dry.
Comments General structure, porosity. This can be prevented by adtm a small quantity of Astm e340 to the etching bath.
Immerse in solution until good contrast is obtained. Other applications of macroetching include: Astm e340 at room temperature.
A better though slower method is to grind the specimen. The usual procedure is to take a roughing cut, then a?
ASTM E – 15 Standard Practice for Macroetching Metals and Alloys
I, mix fresh, grain structure. Fine-grained metal may not give good results in either case. Increase water to increase strain contrast. Immerse specimen in solution at room temperature for 10 to 30 min.
ASTM E – 00 Standard Test Method for Macroetching Metals and Alloys NO_PDF
Metallographic specimens and chemical analyses will provide the necessary detailed information about specific localities but they cannot give data about variation from one place to another unless an inordinate number of specimens are taken. In all cases, the various chemicals should be added slowly to the water or solvent while stirring. The specimen should be cut carefully and then ground gently on lubricated silicon carbide paper.
First, astm e340 is a rather brittle metal and sectioning can be difficult. The abrasives must be of sufficient hardness, and particles on astm e340 laps must be sharp. High-alloy stainless steels and austenitic hightemperature alloys because of their extreme corrosion resistance often will give trouble in etching.
The hightemperature astm e340 are difficult to etch. The use of torch cutting or hot cutting should be used only when necessary to cut a sample from a large piece. Metallographic specimens and chemical analyses will provide the necessary detailed information about speci? Comments Works best on coarse grained Be. The solution should be mixed and placed in a corrosion resistant tray or dish and brought to the operating temperature. It can also be removed by scrubbing the specimen with a vegetable?
Make subsequent additions after foaming from the previous addition has stopped. Specimens produced in this manner are adequate for general inspection. Defects such as coring, cracks, and porthole die welds are identi?