Ignition of bulk 302 stainless steel in oxygen by laser heating

The effect of oxygen pressure on the ignition temperature of cylindrical 302 SS specimens ignited by a focused CW CO2 laser beam in a cool, static, oxygen environment was investigated. The ignition temperature was determined quantitatively from the specimen temperature history obtained from a fast response, near infrared, two-color pyrometer, which recorded the temperature history of a spot approximately 0.5 mm in diameter and located at the center of the cylindrical 302 SS specimen's top surface. Ignition and combustion occurred in three stages. The first stage began with specimen heating and ended with ignition, the second stage corresponded to combustion, and the third stage represented cooling. The physical changes that occurred in the first stage are described.