Ferrite Counting - Material Analysis (Welding)
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Microstructure of Duplex Stainless Steel at 100 micrometers under light microscope. These images were taken with a high resolution camera attached to the light microscope. They are especially relevant in the root cause failure analysis of welding between metals. The particular test employed is called ferrite-count analysis or ferrite-counting.
Ferrite counting used to be done by hand and this was extremely tedious as one would have to look through up to 5800 different images at a time (typical job looks like this; 30 images, 10 nodes per quadrant, 5 quadrants total -> 30x10x5 = 1500 images to analyze). Above you can see gridlines, these separate the image into so called 'quadrants'. Within each quadrant several 'nodes' (different images of the quadrant as a whole) are analyzed by computer software and manually operated.
Now all you have to do it manually select 3 options - No Cross, BLACK CROSS & RED CROSS. Ferrite counting helps us determine the % composition of a metal weld. The two predominant components of welds in the Engineering industry will be that of Austenite and Ferrite.
Ferrite is present wherever you see a Black Cross.
Austenite is present wherever you see No Cross
An overlapping/touching boundary is present wherever you see a Red Cross
X-Ray Fluorescence Composite Analysis
XRF is an acronym for X-ray fluorescence spectroscopy. XRF is a non-destructive analytical technique (especially advantageous for hard to source or expensive samples) used to determine the elemental composition of materials. Handheld XRF analyzers work by measuring the fluorescent (or secondary)
X-rays emitted from a sample when excited by a primary X-ray source. Each of the elements present in a sample produces a set of characteristic fluorescent X-rays, or “unique fingerprints”. These “fingerprints” are distinct for each element, making handheld XRF analysis is an excellent tool for quantitative and qualitative measurements
X-rays are produced by the analyzer and pointed at a sample surface.
The energy causes inner-shell electrons to be ejected.
Outer-shell electrons fill the vacancies left by the ejected electrons and fluorescent x-rays are emitted.
The fluorescent x-rays enter the detector and send electronic pulses to the preamp.
The preamp amplifies the signals and sends them to the Digital Signal Processor (DSP).
The DSP collects and digitizes the x-ray events and sends the spectral data to the main CPU for processing.
The CPU analyzes the spectral data to produce detailed composition analysis.
Composition data and other grade or value identification are displayed and stored in memory for later recall or download to an external PC.
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