The effect of boron and titanium microalloying on the scale formation of AISI 304 austenitic stainless steel in simulated walking beam furnace conditions
Abstract
The effect of microalloying boron and titanium on AISI 304 austenitic stainless steel scale formation is studied. Thermogravimetric tests simulating walking beam furnace conditions are performed at temperatures of 800, 1100, and 1300 °C for 3 h on samples of AISI 304 steels with different alloying amounts of B and Ti. Scaling at 800 °C is negligible on all the samples, while scaling is clear at 1100 and 1300 °C. The thermogravimetric results show that even in small amounts, boron and titanium have an effect on scale growth rate. FESEM microscopy and accompanying EDS analyses are used to study oxidation area element composition. The FESEM images are also used to compare the oxidation zones’ area fractions of metal, pores, and oxide between different alloying amounts for the samples of 1300 °C tests. Calculations for scale formation activation energy are done based on the thermogravimetric data. The steel sample with the lowest alloying of boron and titanium shows a noticeably different growth rate, which is nearly linear in both the 1100 and 1300 °C tests. Differences between alloying amounts in accumulated scale during the 180 min period in kg m−2 are greater at 1100 °C than they are at 1300 °C
