Accession Number : ADA187366

Title :   Evaluation of Thixocast Cartridge Stop Pawls.

Descriptive Note : Final rept.,

Corporate Author : ARMY LAB COMMAND WATERTOWN MA MATERIAL TECHNOLOGY LAB

Personal Author(s) : Smoot, Perry R

PDF Url : ADA187366

Report Date : Sep 1987

Pagination or Media Count : 21

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.

Descriptors :   *GUN COMPONENTS, *CASTINGS, CHEMICAL ANALYSIS, CHEMICAL DISSOCIATION, CRACKS, DEFECTS(MATERIALS), FERRITES, GASES, HARDNESS, HEAT TREATMENT, HIGH RATE, INTENSITY, LOW TEMPERATURE, MAGNETIC PROPERTIES, METALLOGRAPHY, MICROSTRUCTURE, PARTICLES, POROSITY, RADIOGRAPHY, ROUGHNESS, SEGREGATION(METALLURGY), SURFACES, VARIATIONS, VISUAL INSPECTION, MACHINE GUNS

Subject Categories : Metallurgy and Metallography
      Guns

Distribution Statement : APPROVED FOR PUBLIC RELEASE