Metallografic inspection

Metallography is an important tool in quality assurance. In the context of heat treatment and nitriding of steels it can indicate potential for improvement of process.

The microscopic examination of polished or etched surfaces can reveal such information as grain size and shape, distribution of structural phases and non-metallic inclusions. Depending on the magnification micro-segregation can be made visible.

Much in the art of metallography lies in the good sample preparaion. To create a metallographic image, the following steps are necessary and need to be carefully done.

  1. Sampling,
  2. Pregrinding
  3. Embeding
  4. sample labeling
  5. Grinding
  6. Cleaning
  7. Etching
  8. Assessment under the microscope

The classical chemical grain boundary etching is a simple but efficient tool to make grain boundaries visible and to determine the thickness of the “ N Layers”. With help of metallography we see the type, quantity, size, shape, spatial distribution and orientation of the phases more in detail. It is possible determine the deformation degree or and detect the presence of precipitations. Our equipment allows for colour etching with hydrofluoric acid to proof the existence of phases.

images for metallography

Mounting samples

Color etching of a watch steel (LiMi*) (Beraha I)

seawater resistant stainless steel (LiMi*) (Electric etched)

Nitrided steel (optical - Phenom)

Nitrided steel (electron microscopy - Phenom)

equipment for metallography @ ALPS

also check the infrastructure page

Metallurgical studies

 

  • Carbon/Sulphur analyser Horiba EMIA-320V
  • Nitrogen/Hydrogen combustion analyser Bruker Galileo G8 N/H
  • Dew point measurement instrument
  • Leak detector (He and Hydrogen)
  • Reflected-light microscope Nikon Eclipse LV150A (max. magnification 1000x) with image analysis software
  • Stereoscopic zoom microscope Nikon SMZ1500 (max. magnification 112x)

Glow discharge spectrometry GDOES

  • Equipment for preparation and etching of metallographic specimens (including electro-polishing and -etching) :
  • Ripper: Struers Discotom-2
  • Mounting press: Struers LaboPress-3 (Ø30mm)
  • Modular grinding machine: Struers LaboPol
  • Standard grinding and polishing machine: Presi P230
  • Advanced grinding and polishing machine: Struers Tegramin
  • Electric polisher: LectroPol-5