Evaluation of Thixocast Cartridge Stop Pawls.

Abstract

The objective of this work was to evaluate thixocast cartridge stop pawls for the M85 machine gun in accordance with applicable specifications. A lot composed of eight pawls was evaluated and found satisfactory with respect to chemical analysis. However, radiography revealed sponge and centerlines shrink. Magnetic particle and visual inspection revealed severe surface cracking. Metallography showed hot tears, gas porosity, cold shots, inclusions, and gross chemical segregation, resulting in microstructural variation from ferrite to martensite, and hardness variation from 20 to 59 HRC. This segregation persisted through heat treatment. The surface hardness, roughness, and dimension did not conform to specifications, and the castings did not fulfill the specifications. The above defect problems must be resolved before the process can be utilized.

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Document Details

Document Type
Technical Report
Publication Date
Sep 01, 1987
Accession Number
ADA187366

Entities

People

  • Perry R. Smoot

Tags

Communities of Interest

  • Space
  • Weapons Technologies

DTIC Thesaurus Topics

  • Air Force
  • Castings
  • Chemical Analysis
  • Classification
  • Contracts
  • Die Casting
  • Elements
  • Engineering
  • Hardness
  • Heat Treatment
  • Inclusions
  • Materials
  • Materials Science
  • Mechanical Properties
  • Military Research
  • Specifications
  • Surface Roughness

Fields of Study

  • Materials science

Readers

  • Electrical Engineering
  • Metallurgy