Classification of surface defects in aluminum profiles

Reputable American Aluminum Presses Industry Association - Aluminum Extruder Council - constantly conducts master classes (workshops) to improve the qualifications of technical personnel in various areas of production of extruded aluminum profiles. Below is a modern classification of surface defects of aluminum profiles, which was introduced in May 2017 year at one of the master classes [1].

Some of the British terms of aluminum profiles surface defects do not yet have established analogues in Russian. Therefore, the terms used below russkoyazychnye defects or descriptions thereof may need adjustment and adjustment.

"Running" American 6xxx series aluminum alloys

The report examines the defects based on the experience in the production of extruded sections from the 6xxx series alloys most widely used in the USA [1]:

"Soft" aluminum alloys of the 6xxx series:

  • 6360 "Improving the properties"
  • 6063 "General purpose" (analogue of the domestic AD31)
  • 6063 "Increased strength" -T54, -T65

Medium-strength aluminum alloys of the 6xxx series:

  • 6005A
  • 6061/6351 (6061 - analog AD33)
  • 6082 (AD35 analog)

The classification of surface defects profiles 6xxx alloys

defects extrusion

  • Pick-ups - adhered-teaser
  • Blisters - Blisters
  • Speed ​​Cracking - Cracking Speed
  • Tearing – Надрыв
  • Die lines - Risks (longitudinal traces of the matrix)
  • Micro die lines - Micro-risks (matrix micro-traces)
  • Die streaks - Bands, associated with the condition and structure of the matrix
  • Snap mark - After validation facilities Presse
  • Front-end transverse weld - transverse weld
  • Back-end coring - the rear end of a sink mark
  • Longitudinal weld - longitudinal weld
  • Hot spots - Stains from the quench and subsequent thawing at the output table press

See. more on pressing defects here

Defects metallurgical and process after extrusion

  • Coarse Mg2Si - Rough separation Mg2And
  • Mg2Si at grain boundary - Spin Mg2Si grain boundary
  • Coarse grain banding - Bands coarse grain
  • Orange peel - Orange Peel
  • Corrosion pitting - Pitting
  • Corrosion fingerprint - Fingerprint Corrosion
  • Corrosion fretting - corrosion friction
  • Water stain - stains from moisture during storage
  • Spacer marking - Prints of spacers between the rows of profiles
  • Excess lubricant - Defects from excessive greasing workpieces ends
  • Inclusion cast-in - Inclusion of the strand
  • Inclusion extrusion process - Inclusion of the extrusion process

Defects after anodizing

  • Atmosphere corrosion - Atmospheric (general) corrosion
  • Acid corrosion - acid corrosion
  • Alkali corrosion - Alkaline corrosion
  • Rinse water corrosion - Corrosion of washing water
  • Chloride contamination - Chloride contamination of the wash water
  • Dull finish - Stains with different gloss degree
  • Coloring due to Mg2Si - Different shades of color due to variations of dimensions and the number of particles precipitates Mg2And
  • White etch bloom - white film from the etching solution residues
  • Spangle - «Galvanic» surface appearance
  • Inadequate rinsing - Stains from insufficient washing
  • Castle and moat - View pitting, characteristic of the polished surface of the anodized aluminum profiles.

Note, that in the report [1] only the main, Surface defects most important aluminum profiles. for instance, some additional types of defects are also presented in [2], are associated with the surface finish profiles, including, with anodized.

Surface defects aluminum profiles, which manifest themselves in anodizing, have already been partially reviewed on our website (see. defects anodized profiles).


  1. Extrusion Defects Fundamentals & Solutions for Optimum Finish / Jerome Fourmann (Rio Tinto), May 2017.
  2. The Identification and Prevention of Defects on Anodized Aluminum Parts / Ted Short, Metal Finishing Information Service, 2003