OXIDATION BEHAVIORS OF 5 LOW-ALLOY STRUCTURAL-STEELS AT 600-DEGREES-C

Oxidation of five structural steels at 600-degrees-C in three atmosphe res (air, pure oxygen [O2], and a simulated kiln atmosphere) was studi ed. Laboratory weight-loss test results indicated the steel designated ST2 possessed better oxidation resistance than the A36 (UNS K02600), A515 (UNS K02800), A588 (UNS K11430), and SM (designated name) steels. Thermogravimetric analyses for 24 h revealed the kinetics of oxidatio n for the steels studied were linear in air and in pure 02 in the init ial 0.5 h. This was followed by a transient kinetic pattern between li near and parabolic. Similar kinetics were observed for steels in the k iln atmosphere, except that linear behavior was not seen in the initia l 0.5 h. Rate constants and the time exponent of the rate law for the three atmospheres could not be used to predict long-term oxidation beh avior (18 days to 20 days), because each alloy possessed different spa lling characteristics for its product scales in long-term oxidation.