ASTM E1251

ASTM E1251 – Standard Test Method for Analysis of Aluminum and Aluminum Alloys by Spark Atomic Emission Spectrometry

Description:

Significance and Use

5.1 The metallurgical properties of aluminum and its alloys are highly dependent on chemical composition. Precise and accurate analyses are essential to obtaining desired properties, meeting customer specifications, and helping to reduce scrap due to off-grade material.

5.2 This test method is applicable to chill cast specimens as defined in Practices E716 and can also be applied to other types of samples provided that suitable reference materials are available. Also, other sample forms can be melted and cast into a disk, using an appropriate mold, as described in Practices E716. However, it should be noted that some elements (for example, magnesium) readily form oxides, while some others (for example, sodium, lithium, calcium, and strontium) are volatile, and may be lost to varying degrees during the melting process.

Scope

1.1 This test method describes the analysis of aluminum and its alloys by spark-atomic emission spectrometry (Spark-AES). The aluminum specimen to be analyzed may be in the form of a chill cast disk, casting, foil, sheet, plate, extrusion, or some other wrought form or shape. The elements covered in the scope of this method are listed in the table below.

Element	Tested Mass Fraction Range (Wt %)
Antimony	0.001 to 0.003
Arsenic	0.001 to 0.006
Beryllium	0.0004 to 0.24
Bismuth	0.03 to 0.6
Boron	0.0006 to 0.009
Calcium	0.0002 to –
Chromium	0.001 to 0.23
Cobalt	0.4 to –
Copper	0.001 to 5.5
Gallium	0.02 to –
Iron	0.2 to 0.5
Lead	0.04 to 0.6
Lithium	0.0003 to 2.1
Magnesium	0.03 to 5.4
Manganese	0.001 to 1.2
Nickel	0.005 to 2.6
Phosphorus	0.003 to –
Silicon	0.07 to 16
Sodium	0.003 to 0.02
Strontium	0.03 to –
Tin	0.03 to –
Titanium	0.001 to 0.12
Vanadium	0.002 to 0.022
Zinc	0.002 to 5.7
Zirconium	0.001 to 0.12

NOTE 1: The mass fraction ranges given in the above scope were established through cooperative testing (ILS) of selected reference materials. The range shown for each element does not demonstrate the actual usable analytical range for that element. The usable analytical range may be extended higher or lower based on individual instrument capability, spectral characteristics of the specific element wavelength being used, and the availability of appropriate reference materials.

NOTE 2: Mercury (Hg) is intentionally not included in the scope. Analysis of Hg in aluminum by Spark-AES is not recommended. Accurate analysis of Hg using this technique is compromised by the presence of an intense iron interference. Inaccurate reporting of Hg due to these interference effects can jeopardize the current designation of aluminum production as a mercury-free process. To demonstrate compliance with legislated Hg content limits, use of an alternate method capable of analysis with a minimum reporting limit of 0.0001% or lower is recommended. Suitable techniques include but are not limited to GD-MS, XRF (X-ray fluorescence), cold vapor AA, and ICP-MS.

1.2 This test method is suitable primarily for the analysis of chill cast disks as defined in Practices E716. Other forms may be analyzed, provided that: (1) they are sufficiently massive to prevent undue heating, (2) they allow machining to provide a clean, flat surface, which creates a seal between the specimen and the spark stand, and (3) reference materials of a similar metallurgical condition and chemical composition are available.