FERRITIC INCLUSIONS IN NON-FERRITIC TUBE, BAR AND WIRE
Inclusions are small particles or linear ferrite residuals that are usually considered to be undesirable. They may be spherical or elongated. They may originate from two major sources.
The first comes from the material melt, which can contain residual impurities. The second may originate during manufacturing and processing.
Finned Copper Tube with Transitional (land) Zone
In addition, ferrous metal particles such as filings from finning tools can be detrimental to the finished configuration but they can be particularly small and difficult to find.
- Metallic inclusions can create problems when they occur in too high of a concentration.
- Some situations that could be caused by metallic inclusions in tube, bar and wire include pinholes, flange cracks, surface streaks, wire breakage, increased tool wear and tear, increased porosity, potential leaks, poor machinability and cosmetic surface defects.
- Tramp Metal inclusions can be small and may be difficult to find using standard Eddy Current test coils. An example is ferrous particles in austenitic stainless which can seriously affect the final product quality (stainless tube fitting for example).
Stainless Bar with Ferromagnetic Inclusion
- With a Flux Leakage Magnetic Inclusion Detector (MID), consisting of MultiMac® electronics with a special coil sensor to provide a DC field, very small ferrous inclusions in nonferrous tubes can be detected.
- MAC’s Production Comparator PC-VI with null test coils can detect small ferromagnetic inclusions and stringers in non-magnetic stainless steel rods and bars, and can also inspect most austenitic grade products. These include rounds, hexes and custom shapes. These linear inclusions can be detected at any depth in the solid bar product.