Investigation of Hot Cracking Phenomena in Light-Weight Armor Steel Based on the FeMnAl-C Alloy System

The US Army TARDEC has been researching an alternative to current armor steel that is both tough, and light-weight. The studied alloy is based on the Fe-Mn-Al-C system. This study was conducted to investigate and quantify this alloy’s susceptibility to hot cracking phenomena related to casting and welding. Very little research has been done on general weldability of this alloy system, so the results of these tests will be compared to other high Mn steels, and alloys that have undergone cast pin tear testing. Testing will be conducted utilizing button melting tests, autogenous spot welds, and cast pin tear testing. The cast pin tear testing was conducted to measure this alloys susceptibility to weld solidification cracking. The spot welds were used to quantify the susceptibility of the weld heat affected zone (HAZ) to liquation cracking, as well as to observe the solidification structure of the fusion zone. The testing results showed that the FeMnAl system in its current form has a susceptibility to both solidification cracking and to HAZ liquation cracking.