ASTM B953-07
(Practice)Standard Practice for Sampling Magnesium and Magnesium Alloys for Spectrochemical Analysis
Standard Practice for Sampling Magnesium and Magnesium Alloys for Spectrochemical Analysis
SIGNIFICANCE AND USE
This practice, used in conjunction with the following quantitative atomic emission spectrochemical test method, B 954, is suitable for use in manufacturing control, material or product acceptance, certification, and research and development.
SCOPE
1.1 This practice describes the sampling of magnesium and magnesium-base alloys to obtain a chill-cast sample suitable for quantitative atomic emission spectrochemical analysis. The disk in the region to be excited is representative of the melt and gives a repeatability of results that approach that of the reference materials used.
1.2 This practice describes the procedure for representative sampling of molten metal.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in 5.1
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: B953 − 07
StandardPractice for
Sampling Magnesium and Magnesium Alloys for
Spectrochemical Analysis
This standard is issued under the fixed designation B953; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope produce a chill-cast disk. The disk is machined to a specific
depth that represents the average melt composition and pro-
1.1 This practice describes the sampling of magnesium and
duces an acceptable surface for excitation.
magnesium-base alloys to obtain a chill-cast sample suitable
for quantitative atomic emission spectrochemical analysis. The 3.2 Fabricated, cast, or wrought products may be excited
disk in the region to be excited is representative of the melt and directly without remelting; however, accuracy of results may
gives a repeatability of results that approach that of the suffer in highly alloyed samples due to the potential for
reference materials used. elemental segregation.
1.2 This practice describes the procedure for representative
4. Significance and Use
sampling of molten metal.
4.1 This practice, used in conjunction with the following
1.3 The values stated in SI units are to be regarded as the
quantitative atomic emission spectrochemical test method,
standard. The values given in parentheses are for information
B954, is suitable for use in manufacturing control, material or
only.
product acceptance, certification, and research and develop-
1.4 This standard does not purport to address all of the
ment.
safety concerns, if any, associated with its use. It is the
5. Apparatus
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
5.1 Ladle, capable of holding a minimum of 400 g (7.7 oz)
bility of regulatory limitations prior to use. Specific precau-
of molten metal, with a handle of sufficient length to reach into
tionary statements are given in 5.1.
a furnace, trough, or crucible sufficiently deep to obtain a
sample representative of the melt being cast. The ladle may be
2. Referenced Documents
lightly coated with a tightly adhering ladle wash that will not
2.1 ASTM Standards:
contaminate the sample. Boron nitride can be applied at
E401 Practice for Bonding Thin Spectrochemical Samples
elevated temperatures to form a tenacious coating. Warning—
and Standards to aGreater Mass of Material (Withdrawn
Trace moisture in the coating or on the tool may cause
1995)
dangerous spattering. Preheat all sampling tools and molds
E1257 Guide for Evaluating Grinding Materials Used for
prior to use.
Surface Preparation in Spectrochemical Analysis
5.2 Sample Molds, capable of producing homogeneous
B954 Test Method for Analysis of Magnesium and Magne-
chill-cast disks having smooth surfaces, free of surface pockets
sium Alloys by Atomic Emission Spectrometry
and porosity. These castings should have a spectrochemical
3. Summary of Practice
response similar to the reference materials used in preparing
the analytical curves and must have a repeatability from
3.1 Molten metal representative of the furnace melt is
excitation-to-excitation of no more than 2% relative on major
poured directly into a specified mold (described in 5.2.1)to
alloying elements. They must be representative of the melt in
1 the region excited. Several types of molds have been found
These practices are under the jurisdiction of ASTM Committee B07 on Light
Metals and Alloys and are the direct responsibility of Subcommittee B07.04 on
acceptable:
Magnesium Alloy Cast and Wrought Products.
5.2.1 Type A, open cavity mold, is shown in Fig. 1. The
Current edition approved June 1, 2007. Published July 2007. DOI: 10.1520/
advantage of this mold is its simple design and ability to
B0953-07.
produce a sample disk that can be excited around the entire
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
annular area. Mold dimensions can be modified to produce a
Standards volume information, refer to the standard’s Document Summary page on
disk size ranging from approximately 44 to 64 mm (1.75 to 2.5
the ASTM website.
3 in.) in diameter by 10 to 15 mm (0.4 to 0.6 in.) in thickness.A
The last approved version of this historical standard is referenced on
www.astm.org. circular central recess 10 to 20 mm (0.4 to 0.8 in.) in diameter
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B953 − 07
FIG. 1 Type A Mold – Open Cavity Mold and Sample
ononesideofthedisk(analyticalside)facilitatesmachiningof
that side in preparation for excitation. It also promotes a more
uniform freezing of the raised peripheral area. The mold
material should be mild steel and should weigh approximately
2 to 3 kg (4.5 to 6.5 lb).
5.2.2 Type B, center pour mold, is shown in Fig. 2. The
advantage of this mold is that the sample obtained may be
excited around the entire annular area. This mold produces a
horizontally cast disk with the sprue over the center on the
backside. The mold dimensions are such as to produce a disk
approximately 64 mm (2.5 in.) in diameter by 13 mm (0.5 in.)
in thickness. A circular central recess 10 to 13 mm (0.4 to 0.5
in.) in diameter on one side of the disk (analytical side)
facilitates machining of that side in preparation for excitation.
It also promotes more uniform freezing of the raised peripheral
area, but the corresponding raised portion of the mold must not FIG. 3 Type U Mold – U-Block Mold and Sample
be so large as to restrict the throat for the sprue.Aslight taper,
1 to 2°, on the hinged portion of the mold facilitates opening
chill plate produces a spectrochemically homogenous sample
when a disk has been cast. The mold material should be mild
for at least the first third and usually up to two thirds of the
steelandshouldweighapproximately3.5to4.5kg(8to10lb).
length of the U-block sample from chill the cast face (Note 1).
5.2.3 Type U, U-Block mold, is shown in Fig. 3. This side
gated block mold produces a cylindrical block sample of
NOTE 1—To improve the performance and durability of the molds
approximately 40 mm (1.6 in.) in diameter by 60 mm (2.4 in.)
described above, prepare the surface of the mold cavity to minimize the
formationofgaspocketsonthesurfaceofthecastingsandtoresistrusting
high. The mold is placed on top of a massive 150 mm (5.9 in.)
of the mold cavity surface. To do this, blast the inner surface with a sharp
diameter by 50 mm (2.0 in.) thick copper chill plate with a
grit that cuts rather than peens. The resulting finely roughened face is
knurled working surface. The mold material is mild steel. The
essential for obtaining a smooth and uniform surface on the cast disk.
downsprue directionally choked side gate promotes a con-
Next,degreasethemold,placeinacoldfurnace,andraisethetemperature
trolled fill.The strong directional solidification provided by the to 400°C (752°F).At this temperature and throughout the remainder of the
FIG. 2 Type B Mold – Center Pour Mold and Sample
B953 − 07
heating cycle, introduce steam into the furnace. Raise the temperatu
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