ASTM E415-14 pdf free download. Standard Test Method for Analysis of Carbon and Low-Alloy Steel by Spark Atomic Emission Spectrometry.
4. Summary of Test Method
4.1 A capacitor discharge is produced between the flat, ground surface of the disk specimen and a conically shaped electrode. The discharge is terminated at a predetermined intensity time integral of a selected iron line, or at a predetermined time, and the relative radiant energies of the analytical lines are recorded. The most sensitive lines of arsenic, boron, carbon, nitrogen, phosphorus. sulfur, and tin lie in the vacuum ultraviolet region. The absorption of the radiation by air in this region is overcome by evacuating the spectrometer and flushing the spark chamber with argon.
5. Significance and Use
5. 1 This test method for the spectrometric analysis of metals and alloys is primarily intended to test such materials for compliance with compositional specifications. It is assumed that all who use this Lest method will be analysts capable of performing common laboratory procedures skillfully and safely. It is expected that work will be performed in a properly equipped laboratory.
6. Apparatus
6. 1 Sampling Devices:
6.1.1 Refer to Practice E 1806 for devices and practices to sample liquid and solid iron and steel.
6.2 Excüaiioii Source, capable of providing electrical parameters to spark a sample. Sec 11.1 for details.
6.3 Spark Chamber, automatically flushed with argon. The spark chamber shall be mounted directly Ofl the spectrometer and shall be provided with a spark stand to hold a hat specimen and a lower counter electrode of rod form.
6.3. 1 Follow the manufacturer’s recommendations for cleaning the spark chamber (during continuous operation, this typically should be done every 24 h). Follow the manufacturer’s recommendations for cleaning the entrance lens or window (verifier data or other reference sample intensity data can typically indicate when this is necessary).
6.4 Spectroiizeter having a reciprocal linear dispersion of 0.60 nm/mm, or better, in the first order and a focal length of 0.75 m to 3 m. Its approximate range shall be from 145.0 nm to 400.0 nm. Masks shall be provided in the spectrometer to eliminate scattered radiation. The spectrometer shall he provided with an air inlet and a vacuum outlet.
7. Reagents and Materials
7.1 Counter Elect rodes—T he counter electrodes can be silver or thoriated tungsten rods, or other material, provided it can be shown experimentally that equivalent precision and bias is obtained. The rods can vary in diameter from 1 .5 mm to 6.5 mm (depending on the instrument manufacturer) and typically are machined to a 90° or 120° angled tip.
7.1.1 A black deposit will collect on the tip of the electrode. This deposit should be removed between specimens (typically with a wire brush). If not removed, it can reduce the overall intensity of the spectral radiation or transfer slight amounts of contamination between specimens, or both. The number of acceptable excitations on an electrode varies from one instrument to another, and should be established in each laboratory.
Note 4—It has been reported that thousands of excitations can be performed on a thorianed tungsten electrode before replacement is necessary.ASTM E415 pdf download.