Reference materials for analysis of C in high purity iron

A set of reference materials was developed for analysis of C in high purity iron. The starting material was a specially developed electrolytic iron an d was purified in an induction-melting furnace with a cold-copper crucible under ultra-high vacuum. After machining the surface layer, the ingots were forged and then drawn to wires. The surface layer of the wires was machine d again to eliminate the contamination possible to exist during this manufa cturing process. The wires were finished to the pins of phi 3.9mm x 11.4mm with the weight of Ig. The pins were plated with nickel to protect further contamination during handling. Uniformity of these materials was confirmed by analyzing several parts of the wires. The concentrations of C were deter mined by cooperative analysis of two independent laboratories. This set of reference materials is applicable to analysis of C in the concentration ran ge of 1-20 mass ppm.