Patent ID: 8529708

Claim:
A method for making armor plate resistant to armor piercing small arms ammunition, the method comprising: providing a steel plate having a thickness and a nominal chemical composition in weight percent of 0.38-0.44 C, 1.65-2.00 Ni, 0.65-0.90 Cr, 0.20-0.30 Mo, 0.15-0.35 Si, 0.60-0.85 Mn, P less than or equal to 0.035, S less than or equal to 0.05, balance Fe and other incidental impurities; carburizing one side of the steel plate to produce a carburized plate having a carburized side and a non-carburized side, the carburized side of the steel plate having a carbon concentration of at least 0.9 percent by weight and the non-carburized side having a carbon concentration of between 0.38 and 0.45 percent by weight, and heating the carburized plate at a temperature range between 1225 and 1275 degrees Fahrenheit for a time between 15 to 45 minutes and thereafter heating the carburized plate at a temperature range between 1525 and 1575 degrees Fahrenheit for a time between 10 and 30 minutes.