ASTM E407 Microstructure of Den
ASTM E407 Metal Microstructure


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APM Testing provides A2LA accredited services for metal microstructure testing at a fair price, with prompt delivery, and a detailed test report. Our laboratory also provides laboratory services for plastic testing, metal testing, rubber testing, oil testing, paint testing, plating testing, adhesive testing, circuit board testing, and other testing.

Purpose: Etch a metal sample to reveal its microstructure per ASTM E407.

Sample: One metal part.

Price & Delivery: Contact us for a quote.

Basic Description: ASTM E407 is a method of etching a metal sample to reveal its microstructure. On a microscopic scale, metal is made up of many grains which can vary in shape and size. Alloying elements in the metal sometimes separate into microscopic particles with distinct shapes. This microstructure can be inspected by mounting, cross sectioning, and polishing per ASTM E3 followed by etching per ASTM E407. ASTM E407 specifies what etching chemicals (usually acids) and procedures are required to reveal the microstructure of different types of metals. Carbon steel has several structures such as ferrite, pearlite, and martensite depending on how the carbon is distributed in the material. Cast aluminum often has a dendritic (fern like) structure formed by the distribution of silicon. Forgings often show elongation of individual grains which indicate the orientation and flow of the material. Differences in microstructure are important because they can help to determine if a metal has been subjected to corrosive chemicals, is softer or harder at the surface, has been deformed, was welded properly, or has been over-heated. Microstructural results are typically reported as pictures of the microstructure along with a paragraph interpreting the meaning of the structure.

Limitations: Good microstructural results require significant preparation to obtain a mirror finish with no scratches or edge rounding prior to etching. High magnification optical microscopy and sometimes scanning electron microscopy (SEM) is required to reveal important details. An experienced metallurgist is required to interpret the images created..


  • Reichert Polyvar, Optical Microscope with Digital Camera, 20 to 2,000X Magnification
  • JEOL 6360LV, Scanning Electron Microscope (SEM), 30 to 100,000X Magnification

Method Publisher:


  • Microstructure
  • Ferrite
  • Pearlite
  • Martensite
  • Metallographic Examination
  • Microetching Metal
  • Microstructural Analysis

Related Techniques: