Overview
ISO 22961:2008 specifies an atomic absorption spectrometric (AAS) method for determining the mass fraction of iron (Fe) in titanium and titanium alloys. The method covers samples with iron mass fractions from 0.005 % to 2.0 % (m/m). It defines sample size, reagents, apparatus, calibration, measurement conditions and result calculations for routine laboratory analysis.
Key Topics and Requirements
- Scope and applicability: Intended for titanium and titanium alloys; iron range 0.005–2.0 %.
- Sample size and sampling: Test portion of 0.50 g, with at least duplicate determinations; sampling procedure to be agreed until a dedicated sampling standard is published.
- Reagents and reference materials: Analytical-grade reagents and water (ISO 3696 grade 2). Key reagents include hydrochloric (HCl), hydrofluoric (HF), nitric (HNO3) acids, boric acid, and certified iron standard solutions prepared as described.
- Sample preparation: Dissolve the test portion in HCl and HF, oxidize with HNO3, add boric acid, and dilute to volumetric solution for AAS measurement.
- Instrumentation and settings: Atomic absorption spectrometer with an iron hollow cathode lamp; wavelength 248.3 nm; air/acetylene flame specified.
- Calibration and working curve: Calibration solutions are prepared by fortifying titanium digests with known iron standards; a working curve (absorbance vs. mg Fe/100 ml) is constructed and shifted to pass through the origin for sample quantification.
- Calculation and reporting: Provides formulae for converting measured concentrations to mass fraction (WFe) with separate expressions for