Influence of heat treatment on the microstructure and mechanical properties of Alloy 718 base metal and weldments Metadata

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  • Main Title Influence of heat treatment on the microstructure and mechanical properties of Alloy 718 base metal and weldments


  • Author: Mills, W.J.
    Creator Type: Personal


  • Name: Hanford Engineering Development Laboratory
    Place of Publication: Richland, Washington
    Additional Info: Hanford Engineering Development Lab., Richland, WA (USA)


  • Creation: 1979-06-01


  • English


  • Content Description: Effect of heat treatment on the metallurgical structure and tensile properties of three heats of Alloy 718 base metal and an Alloy 718 GTA weldment were characterized. Heat treatments employed were the conventional (ASTM A637) precipitation treatment and a modified precipitation treatment designed to improve the toughness of the weldments. The GTA weldments were characterized in the as-welded condition. Light microscopy, thin foil, and surface replica electron microscopy revealed that the microstructure of this superalloy was sensitive to heat treatment and heat-to-heat variations. The modified aging treatment resulted in a larger grain size and a more homogeneous microstructure than the conventional treatments. The morphology of the primary strengthening ..gamma.. phase was found to be finer and more closely spaced in the conventionally treated condition. Room and elevated temperature tensile testing revealed that the strength of the conventionally treated alloy was generally superior to that of the modified material. The conventional aging treatment resulted in greater heat-to-heat variations in tensile properties. This behavior was correlated with variations in the microstructure resulting from the precipitation heat treatments. The precipitate morphology of the GTA weldments was sensitive to heat treatment. The Laves phase was present in the interdendritic regions of both heat-treated welds. The modified aging treatment reduced the amount of Laves phase present in the weld zone. Room and elevated temperature tensile properties of the precipitation hardened weldments were relatively insensitive to heat treatment, suggesting that reduction in Laves phase from the weld zone had essentially no effect on tensile properties. As-welded GTA weldments exhibited lower strength levels and higher ductility values than heat-treated welds.


  • STI Subject Categories: 220200 -- Nuclear Reactor Technology-- Components & Accessories
  • Keyword: Nickel Base Alloys
  • Keyword: Alloys
  • Keyword: Filler Metals
  • Keyword: Welding 360103* -- Metals & Alloys-- Mechanical Properties
  • Keyword: Fabrication
  • Keyword: Heat Treatments
  • Keyword: Modifications
  • Keyword: Molybdenum Alloys
  • Keyword: Crystal Structure
  • Keyword: Welded Joints
  • Keyword: Chemical Composition
  • Keyword: Nickel Alloys
  • Keyword: Fracture Properties
  • Keyword: Joining
  • STI Subject Categories: 22 General Studies Of Nuclear Reactors
  • Keyword: Gas Tungsten-Arc Welding
  • Keyword: Inconel Alloys
  • Keyword: Chromium Alloys
  • Keyword: Hardening
  • Keyword: Mechanical Properties
  • Keyword: Testing
  • Keyword: Joints
  • Keyword: Inconel 718
  • Keyword: Microstructure
  • Keyword: Morphology
  • Keyword: Surfaces
  • Keyword: Aging
  • Keyword: Arc Welding
  • Keyword: Precipitation Hardening
  • STI Subject Categories: 36 Materials Science
  • Keyword: Niobium Alloys
  • Keyword: Laves Phases
  • STI Subject Categories: 360102 -- Metals & Alloys-- Structure & Phase Studies
  • Keyword: Diagrams


  • Name: Office of Scientific & Technical Information Technical Reports
    Code: OSTI


  • Name: UNT Libraries Government Documents Department
    Code: UNTGD

Resource Type

  • Report


  • Text


  • Report No.: HEDL-TME-78-54
  • Grant Number: EY-76-C-14-2170
  • DOI: 10.2172/6016371
  • Office of Scientific & Technical Information Report Number: 6016371
  • Archival Resource Key: ark:/67531/metadc1099829


  • Display Note: Dep. NTIS, PC A06/MF A01.