Thermal Process Creates Maximum-Strength Highly Ductile Steels in 3 Sec.May 1, 2008
SFP Works, LLC, Washington, MI, has developed a globally patented rapid thermal-processing technology, Flash Bainite, that creates what the company describes as maximum-strength steels with unparalleled ductility. The technology requires neither expensive alloying elements nor time-consuming, capital-intensive thermo-mechanical processing.
Flash Bainite in low-carbon alloys reportedly has achieved 265-275 ksi while maintaining 8-9-percent ductility. This mechanical-property combination makes Flash Bainite stronger pound-per-pound than titanium-6Al-4V STA bar, according to company officials, who claim that lean-chemistry dual-phase products with a Flash Bainite/ferrite microstructure have been made that surpass the strength and ductility of commercially available dual-phase steels. The process is said to develop unique mechanical properties never before seen in readily weldable iron-based alloys.
Conventional advanced high-strength steel (AHSS) is heavily cold-rolled, heated to 1350-1600 F for 5 min. in an energy-intensive continuous-annealing oven, water-quenched and oven-tempered for an additional 5 min.
In contrast, this new process rapidly heats the steel to 1350-2400 F within less than 1 sec. using an induction coil or an oxygen/propane multi-point flame. Within a few seconds of reaching peak temperature, the steel is rapidly quenched in room-temperature water. This flash processing, according to company officials, leads to beneficial drastic differences in microstructure when compared to other steels. In addition, thermal energy use is negligible, especially when compared to the large ovens of continuous-annealing lines.