What type of steel contains boron as an alloying element?

Advanced high-strength steel (AHSS) is specifically designed to achieve superior strength and ductility, making it ideal for automotive applications where safety and performance are critical. Boron is added to this type of steel as an alloying element to enhance hardenability, which allows the steel to achieve higher strength levels through heat treatment processes. This property is particularly valuable in the design of vehicle components that must absorb and dissipate energy effectively during a collision, thus improving safety outcomes.

In contrast to advanced high-strength steel, mild steel tends to have lower strength and is primarily composed of iron with a minimal carbon content, making it less suitable for high-performance applications. High carbon steel contains higher levels of carbon, which increases hardness but can reduce ductility. Stainless steel, known for its resistance to corrosion, contains chromium (and sometimes nickel) rather than boron as a key alloying element. Each of the other types of steel serves distinct purposes, but it is the unique properties of advanced high-strength steel, particularly with the inclusion of boron, that make it the correct answer in this context.