ASTM E716-16(R2021) pdf free download

ASTM E716-16(R2021) pdf free download.Standard Practices for Sampling and Sample Preparation of Aluminum and Aluminum Alloys for Determination of Chemical Composition by Spark Atomic Emission Spectrometry
6.1 Ladle, capable of holding a minimum of 250 g (8.8 oz) of molten metal, with a handle of sufficient length to reach into a furnace, trough, or crucible. The ladle should be lightly coated with a tightly adhering ladle wash that will serve in part to prevent contamination of the sample and also prevent contact of molten aluminum with metal oxides, that is, rust. (Warning—Traces of moisture in the coating may cause dangerous spattering.) N OTE 1—A suitable ladle wash may be prepared as follows: Mix 255 g (9 oz) of fine whiting (CaCO 3 ) with 3.8 L (1 gal) of water and boil for 20 min. Add 127 g (4.5 oz) of sodium silicate solution (40 °Bé to 42 °Bé) and boil for 30 min. Stir well before using. N OTE 2—Molten aluminum in contact with rust may initiate a thermite reaction.
6.2 Sample Molds shall be capable of producing homog- enous chill-cast disks having smooth surfaces, free of surface pockets and porosity. These chill cast disks should have a spectrochemical response similar to the reference materials used in preparing the analytical curves and should at least have a spark to spark repeatability of no more than 2 % relative on major elements. They must be representative of the melt in the region excited. Several types of molds have been found acceptable: 6.2.1 Type B Mold 4 center-pour mold, is shown in Fig. 1. This mold produces a horizontally cast disk with the sprue over the center of one side. The mold dimensions are such as to produce a disk approximately 50 mm to 64 mm (1.97 in. to 2.5 in.) in diameter by 6 mm to 13 mm (0.24 in. to 0.50 in.) in thickness. A circular central recess 10 mm to 20 mm (0.4 in. to 0.8 in.) in diameter on one side of the disk facilitates machin- ing 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 be so large as to restrict the throat for the sprue. A slight taper, 1° to 2°, on the hinged portion of the mold facilitates opening when a disk has been cast.N OTE 3—About sample molds: Previously two relatively simple types of massive iron or steel sample molds were considered suitable, Type A and Type B. Type A molds produced vertical chill cast samples with the sprue and riser on the edge ofthe sample, as opposed to the Type B which produces a horizontal chill cast sample with the sprue and riser on the back of the sample. The Type A sampler was later found to not produce a repeatable sparking surface, even in the restricted sparking areas. The Type A mold was removed from the list of recommended conventional molds. Because many people are familiar with the terms “Type A” and “Type B” molds, reference to “Type B” mold remains in the text of this standard even though reference to the “Type A” no longer appears.
6.2.2 Scissor Mold 5 is shown in Fig. 2. This mold produces disks that are 60 mm (2.4 in.) in diameter and 13 mm (0.5 in.) thick and weigh approximately 100 g (3.5 oz). The mold consists of two halves weighing about 3 kg (6.6 lbs). The halves are connected by a pivot bolt which allows the halves to function as scissors. When the upper halfwith the sprue hole is moved to cover the sample cavity in the lower half, molten metal is poured into the riser cup, through the sprue hole into the sample cavity. After the metal has frozen, the user holds the steel spring heat dissipater surrounding one handle and strikes the other handle on the ground causing the upper half to pivot away and shear off the riser at the sprue. The sample and the sprue can then be easily removed.