Metal alloy material verification for Quality Control (QC) and Quality Assurance (QA) has never been more important for safety. From primary metal production, to the metal service center, to component fabrication, to final product assembly, the potential for material mix-ups and the need for traceability are a constant concern at every step. Material verification prior to fabrication or shipping of metal alloy products is critical to ensure that the correct material is sent to the customer and that it is used for the right application. The use of wrong or out-of-specification metal alloys can lead to premature and potentially catastrophic part failures that can be very expensive, damage a business’s reputation, and result in loss of life. Alloy verification using portable x-ray fluorescence (XRF) has become the method of choice for achieving assurance and peace of mind. Before Total QualityManagement (TQM ) and Six Sigma methodology raised awareness of the need for better quality control practices, many QC departments relied on less sophisticated and less rigorous inspection methods, or relied solely upon material test reports (MTRs) supplied with their alloy components. MODERN TECHNOLOGY As alloy testing instruments have become less expensive, Easier to use, faster, more accurate and precise, the practice of total reliance on a questionable MTR paper trail is no longer tolerated by many quality managers. Today’s QA/QC inspectors and manufacturing engineers have access to powerful testing tools that eliminate reliance on dubious paperwork in favor of empirical test results conducted in their facilities. Thanks to pioneering advancements in handheld XRF technology by Thermo Fisher Scientific, quality control and inspection personnel can test thousands of metal alloy samples per day accurately and nondestructively. In fact, even junior inspectors are capable of turning out large amounts of quality testing data with the highest confidence and integrity of results. Point-and-shoot testing has become a reality with Thermo Scientific™ Niton™ XL3t Series XRF analyzers. Typical testing times are 2 to 5 seconds to identify and show the alloy grade on the VIP™ tilting color touch-screen display, with lab-quality chemical analysis requiring a few seconds longer to obtain more precise results. Little or no sample preparation is needed for alloy samples with relatively clean surfaces, regardless of shape or size. From a single strand of 1 mm wire to finished weld beads, to rods, bolts, plates, and complete fabricated assemblies, the Niton analyzer can test a wide variety of materials by just touching the instrument to the sample and initiating measurement with a brief trigger pull. EVALUATING PERFORMANCE When potential users are evaluating the performance of analytical instrumentation, they are generally concerned with two criteria: speed and accuracy. What many do not understand is that there are two distinct factors to consider when asking “How accurate is it?”: • Precision – This is a measure of repeatability, or the degree of agreement between individual measurements in a set of measurements, all of the same quantity. • Accuracy – This is a measure of reliability, and is the difference between the true value of a measured quantity and the measured value. Most analytical instrumentation reports statistical precision along with the quantitative measurement results. Precision is a function of the statistical analysis Of the raw data, whereas accuracy must be determined by testing samples with known values, and comparing the measured results to the known values. However, since even the best laboratory methods used to provide these values have statistical limitations in both precision and accuracy, true value is never really known, even in a “certified standard.” TESTING THE NITON XL3t In our performance testing, each alloy sampled was measured under the same conditions multiple times. While the performance data below can be considered typical, performance of individual instruments of this configuration under varying conditions may differ slightly from those shown here. Analyzer against the values of certified reference materials for Stainless Steel 321 and Hastelloy C-276. The indicated times are total measurement times. Regarding XRF instrumentation, increases in measurement time relate directly to improvement in precision. With XRF analysis, each fourfold increase in measurement time improves the precision for each element by a factor of two. The measurement accuracy, coupled with the Niton XL3t’s unparalleled testing speed, means high throughput with real-time, traceable results you can depend on. By combining advanced electronics and materials technology with the most powerful x-ray tubes ever used in handheld XRF instruments (up to 50 kV), the Niton XL3t is in a class by itself. With multiple primary filters for optimal sample excitation and a geometrically optimized large area drift detector (GOLDD+) option to target light elements from magnesium (12) to sulfur (16), the Niton XL3t provides an analytical range, speed, and precision that is unmatched in any other handheld XRF instrument.
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