Chapter 56. Machining Damage Cracks: How to Find and Characterize Them by Fractography

  1. Waltraud M. Kriven and
  2. Hua-Tay Lin
  1. George D. Quinn,
  2. Lewis K. Ives and
  3. Said Jahanmir

Published Online: 26 MAR 2008

DOI: 10.1002/9780470294826.ch56

27th Annual Cocoa Beach Conference on Advanced Ceramics and Composites: B: Ceramic Engineering and Science Proceedings, Volume 24, Issue 4

27th Annual Cocoa Beach Conference on Advanced Ceramics and Composites: B: Ceramic Engineering and Science Proceedings, Volume 24, Issue 4

How to Cite

Quinn, G. D., Ives, L. K. and Jahanmir, S. (2003) Machining Damage Cracks: How to Find and Characterize Them by Fractography, in 27th Annual Cocoa Beach Conference on Advanced Ceramics and Composites: B: Ceramic Engineering and Science Proceedings, Volume 24, Issue 4 (eds W. M. Kriven and H.-T. Lin), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470294826.ch56

Author Information

  1. Ceramics Division, National Institute of Standards and Technology, Gaithersburg, MD 20899

Publication History

  1. Published Online: 26 MAR 2008
  2. Published Print: 1 JAN 2003

ISBN Information

Print ISBN: 9780470375846

Online ISBN: 9780470294826

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Keywords:

  • machining cracks;
  • ceramics;
  • interlocking grain;
  • fractographic;
  • rectangular bars

Summary

Machining cracks may control strength and performance of finished ceramics. Machining cracks previously had been thought to be difficult or impossible to detect and characterize, especially in toughened ceramics with interlocking grain microstructures that create rough fracture surfaces. New fractographic examinations have shown that machining damage leaves telltale markings on fracture surfaces that may be easily detected by fractographers using simple fractographic techniques. A comprehensive study with over 400 ground rods and rectangular bars was conducted on one commercial ceramic to study the effects of various machining conditions. Crack size and shape strongly depended upon the machining conditions, and in particular, on the grinding wheel grit size. In some instances, specimens broke from the material's inherent flaws and machining damage had no effect on strength.