Standard Practice for Sampling Aluminum Ingots, Billets, Castings and Finished or Semi-Finished Wrought Aluminum Products for Compositional Analysis

Abstract

5.1 Products covered by this practice are unwrought aluminum ingots, billets, and castings and unclad wrought aluminum sheet, plate, rolled or cold finished extrusions, extruded profiles, wire, rod and bar. Machined wrought products (finished or semi-finished) are excluded (see Note 3). These practices, used in conjunction with the appropriate sample preparation techniques in Practices E716 and the Test Methods E1251, E3061, and EN 14242, are suitable to determine if the piece sampled meets the chemical composition limits registered with the Aluminum Association Inc.4 or other specified chemical composition limits for the alloy. Analysis of such samples shall not supersede the analysis of samples taken during pouring of castings or ingots in accordance with Practices E716 and analyzed in accordance with Test Methods E1251, E3061, or EN 14242 and shall not be used for determining compliance with chemical composition requirements for an entire cast lot or part thereof. Note 3: Sampling machined pieces of products pose a particular problem because the piece itself may not be a representative sample of the original cast chemical composition. Larger differences may be expected between an analysis obtained from samples taken in accordance with this practice and the original cast analysis of samples taken during pouring of castings or ingot. Note 4: Portable Spark-AES and hand held XRF instruments should not be used to determine if the piece sampled meets chemical composition limits registered with Aluminum Association Inc or other specified chemical composition limits for the alloy. 5.2 Users should be aware that chemical compositions determined using samples taken from unwrought aluminum ingots, billets, and castings and finished or semi-finished products might differ from the bulk chemical composition determined using samples taken when ingots or castings are poured. This difference can be due to elemental segregation upon solidification, sampling a non-homogenous section of the ingot or billet, removal of enriched material, or depleted areas of solidified material by subsequent procedures such as ingot scalping, the removal of risers from castings, or machining. Note 5: When aluminum solidifies, macro-segregation may cause the chemical composition to vary throughout the ingot or casting. Certain areas may have enhanced or depleted concentrations of some elements relative to the average bulk chemical composition. Remnants of the macro-segregation may be retained in finished and semi-finished products. The sampling procedures described in this practice are designed to provide a laboratory sample for analysis which represents the chemical composition of the piece by taking samples in a way that symmetrically includes the various enhanced and depleted zones for example, sampling across the radius of a round ingot, and so forth.