Which of the following metals oxidizes rapidly, making it suitable for oxyfuel cutting?

The rapid oxidation of a metal plays a critical role in oxyfuel cutting since it allows for more efficient combustion when the oxyfuel flame is applied. Straight carbon steel is particularly suitable for this method due to its high carbon content, which enables it to ignite and oxidize quickly when exposed to an oxygen-rich flame. This oxidation process generates heat that is necessary to maintain the cutting reaction through the melting and burning of the steel.

In contrast, other metals mentioned do not oxidize as rapidly in the context of oxyfuel cutting. Stainless steel has a higher chromium content, which forms a protective oxide layer that makes it more resistant to oxidation and, therefore, less responsive to oxyfuel cutting. Brass, an alloy made primarily of copper and zinc, also does not oxidize quickly; it has a lower melting point and can be problematic when cut with a flame due to potential vaporization of the metals. Aluminum, while it can oxidize rapidly, forms a tough oxide layer that can inhibit further oxidation and difficult to cut using traditional oxyfuel methods.

Therefore, straight carbon steel is indeed the most suitable option for oxyfuel cutting in this context because of its ability to oxidize quickly and sustain the cutting process effectively.