Characterizing Iron Based Historical Specimens - Struers

George’s Rules for Pain-free Specimen Preparation

  • Use the gentlest possible sectioning equipment: abrasive cut off saw or precision saw only
  • Use blades developed for metallography, not for production cutting
  • Avoid shrinkage gaps when mounting
  • Start grinding with the finest possible abrasive
  • Keep the polishing surface uniformly covered with abrasive and lubricant
  • Use proper loads

Revealing the Microstructure

  • Nital and picralare good to assess the general structure
  • Selective etchants are excellent for phase identification and measurements, e.g., alkaline sodium picrate to color cementite
  • Prior-austenite grain boundaries in martensite can be revealed using aqueous saturated picric acid plus HCland a wetting agent at 80-90°C
  • Color “tint” etchants reveal details about grain orientation, chemical segregation and residual deformation and are phase specific
  • Choose the best illumination mode, e.g., dark field to reveal grain boundaries, polarized light for inclusions, and NomarskiDIC to reveal height differences between constituents that polish at different rates

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resourcesThe articles and presentations that can be down-loaded from this web site are based upon work done by GFV while employed at Bethlehem Steel (1967-1983), Carpenter Technology (1983-1996), Buehler Ltd. (1996-2009) and Struers (2009-Present) and from the authors consulting work for companies such as, Latrobe Steel, Scot Forge, etc., and from his litigation work. GFV's bylined articles appearing in various issues of the ASM Handbook series have been listed here courtesy of ASM International, Materials Park, Ohio.

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