Accession Number:

ADA282433

Title:

Metallurgical Examination of Failed T-158 Cast Austempered Ductile Iron (CADI) Track Shoes

Descriptive Note:

Final rept.

Corporate Author:

ARMY RESEARCH LAB WATERTOWN MA MATERIALS DIRECTORATE

Report Date:

1994-06-01

Pagination or Media Count:

46.0

Abstract:

The U.S. Army Research Laboratory ARL, Materials Directorate MD conducted a metallurgical examination of prototype cast austempered ductile iron CADI tank track shoe bodies at the request of the U.S. Army Tank-Automotive Command TACOM. The T-158 track bodies had failed during field testing on an MlAl battle tank. Each of the failed parts had been previously fitted with an ice cleat in service which most likely caused an undue stress concentration. The test results indicated that the failure was the result of poor part design and process control. The CADI track shoes had been fabricated according to the dimensional requirements of a forged component, instead of a separate cast design. The CADI material exhibited a variation in mechanical properties. Retained austenite measurements by X-ray diffraction correlated with the differences observed in mechanical properties. Chemical analysis revealed a high level of silicon which adversely affected the fracture toughness of the material. The CADI contained a low but acceptable nodule count and some of the nodules were flaked which decreased fatigue and impact resistance. Recommendations were made by ARL to redesign the track shoe utilizing casting technology criteria and to control the chemistry and microstructure. Metallurgical examination, Cast austempered ductile iron, Retained austenite.

Subject Categories:

  • Properties of Metals and Alloys
  • Combat Vehicles
  • Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE