JFE TECHNICAL REPORT
No.15 Special Issue on "Steel Bar and Wire Rod"
Quenched and tempered carbon steel for machine structural use (e.g., S45C class) had been applied formerly as a steel material for construction machinery parts and other applications with similar requirements.
Later, application of V-added quenched and tempered free steel was expanded with the aim of omitting the quenching and tempering process. However, in recent years, demand for low alloy (V less) quenched and tempered free high strength steel has become increasingly strong in response to the sharp rise in the prices of V and other alloying elements.
Based on these circumstances, JFE Bars & Shapes developed a self tempered type quenched and tempered free high strength steel (hereinafter, TQF® bar), with the aim of omitting the quenching and tempering process and realizing a low alloy product. With TQF® bar, quenching is limited to the surface of the steel material, and is performed with an on line water cooling device installed at the Sendai Works Bar Mill.
Read full technical paper at http://www.jfe-steel.co.jp/en/research/report/015/pdf/015-07.pdf
(Source - JFE)