Oxidation behavior of carbon steel in simulated kerosene combustion atmosphere: A valuable tool for fire investigations

Abstract

Summary Fire investigations aim to establish the origin and cause of fires by collecting and analyzing the comprehensive fire‐related evidences. Metallic materials exposed to the fire scene environments are usually subjected to melting and/or high‐temperature oxidation, and they have been considered vital parameters for temperature determination, as recommended in NFPA 921. The oxide characteristics obtained from the conventional fire investigations primarily rely on simple visual observations such as the variations in oxide color, the so‐called “oxidation patterns.” However, such information is not sufficiently convincing due to the complex nature of oxides formed in the fire scene. The oxide color is strongly affected by the type of oxide, the oxide thickness, the concentration of contaminant, and the interactions among different oxides. In this study, Q235 structural steel samples have been exposed to high‐temperature air and simulated kerosene combustion conditions at certain temperatures and for indicated periods. The oxidation rate was examined by thermogravimetric analysis. The morphologies and microstructures of the oxide scales were investigated by scanning electron microscopy, energy dispersive spectroscopy, and X‐ray diffractions. The results show that the oxide properties are strongly dependent on the oxidation temperature and oxidation atmospheres. These oxidation behaviors are expected to provide useful information on identifying fire characteristics.

Influence of liquid accelerant on scaling behavior of stainless steel in fire: An experimental study

“…On the other hand, oxide scale formed on metallic materials during a fire might reveal information about fire temperature and the composition of atmosphere. The growth and morphology of surface oxide scale and the metallurgical microstructure of alloy can be useful in determining the maximum temperatures reached, similar to the tests already performed on copper, carbon steel and aluminum alloy . Therefore, combination of the oxide scale and metallurgical microstructure technique could be helpful to reconstruct fire scenes.…”

“…As for the effect of accelerant, the combustion products of kerosene, such as CO 2 , H 2 O, and SO 2 , are more aggressive than O 2, which might be deleterious to the chemo‐stability of protective scale. The detailed mechanism has been discussed in our previous work . It is worth noting that the influence of temperature and accelerant on scaling behavior for stainless steel is different to that for aluminum alloy and copper in some extent.…”

“…A horizontal three zones electric furnace equipped with quartz tube is used as reaction furnace for heating the samples at maintained temperatures. To simulate kerosene combustion conditions, a separate combustion chamber was established in an adjacent furnace, and the two furnaces were connected in series, as shown in previous work . The kerosene fuel was injected through a nozzle at a pumping rate of 1.5 SCCM (standard‐state cubic centimeter per minute), mixed with air that was introduced at a flowing rate of 20 SCCM, and ignited in the combustion furnace.…”

“…To simulate kerosene combustion conditions, a separate combustion chamber was established in an adjacent furnace, and the two furnaces were connected in series, as shown in previous work. [5][6][7] The kerosene fuel was injected through a nozzle at a pumping rate of 1.5 SCCM (standard-state cubic centimeter per minute), mixed with air that was introduced at a flowing rate of 20 SCCM, and ignited in the combustion furnace. The kerosene-air combustion atmosphere flowed into the reaction furnace through the quartz tube.…”

“…The detailed mechanism has been discussed in our previous work. [5][6][7] It is worth noting that the influence of temperature and accelerant on scaling behavior for stainless steel is different to that for aluminum alloy and copper in some extent. The car- Finally, the microstructures of stainless steel after hightemperature exposure are illustrated in Figure 8.…”