CINDAS often gets questions about the difference between the MMPDS and the AHAD. In many regards the MMPDS and AHAD complement each other. The Metallic Materials Properties Development Standardization Handbook (MMPDS) is the primary source of statistically based allowables for metallic materials and fastened joints used in the design of aerospace vehicle structures in the US. In general the Aerospace and High Performance Alloy Database (AHAD) contains more materials (over 300 alloys) and more material properties characteristic data. Examples of the differences for heat-resistant alloys are:

MMPDS-14 (heat-resistant alloys)

• 15 alloys
• Major alloys:
      A-286
      Hastelloy X
      Inconel 600
      Inconel 625
      718
      X-750
      Rene 41
      Waspaloy
      L-605

AHAD (heat-resistant alloys, nickel- and cobalt-based)

• 80 alloys
• all 15 from MMPDS

Hastelloy X

• MMPDS
  - 1 page of text
  - 6 tables and figures
  - only allowables data
• AHAD
  - 7 pages of text
  - 97 tables and figures
  - covers full range of properties, conditions and environments
• AHAD
  - information on:
      microstructure
      corrosion
      heat treatment
      fatigue
      fracture toughness
      FCG
      forming
      welding