Accession Number:



Helmets. Investigation of Factors Responsible for Service Cracking of M1 Helmets.

Descriptive Note:

Experimental rept.,

Corporate Author:


Personal Author(s):

Report Date:


Pagination or Media Count:



The object is to examine helmets which cracked in service and during processing with the view of assisting the helmet fabricators and the helmet steel producers in improving the quality of the steel and the methods of fabrication to eliminate service failure and to reduce the manufacturing breakage to a minimum. Examination of helmets which cracked in service and during processing indicates that breakage is primarily associated with a highly stressed condition resulting from extremely severe cold forming operations. Notches, generally confined to the rim of the visor, act as stress raisers and increase the tendency towards edge cracking. These notches result from nicks in the trimming dies and may be eliminated by more frequent dressing of the dies. Improperly controlled heat treatment of the austenitic manganese steel employed, resulting in the formation of brittle layers, grain boundary carbide networks, streaks of undissolved carbides, etc. embrittle the steel sufficiently to greatly increase the tendency to crack in service and break while being formed. A new specification has been put into effect to control the quality of the steel being delivered to the helmet fabricators. It is believed that better control of the steel quality will decrease, but will not entirely eliminate, the tendency of the M1 helmet to crack in service. Changes in manufacturing techniques or in the type of steel used for helmets are believed necessary to completely eliminate the cracking tendency.


Subject Categories:

  • Metallurgy and Metallography
  • Fabrication Metallurgy
  • Protective Equipment

Distribution Statement: