The principle and implementation of a novel hot rolling process is introduced here. Super-tough steels with ultra-fine grained microstructure can be produced by a Thermomechanical Nonrecrystallization Control Process (TNCP), which is one potential candidate for the future commercial production of steels of this kind. A conventional carbon-manganese structural steel was treated here by TNCP using a laboratory roller. Charpy, V impact tests showed toughness readings of ultra-arctic steels for this material, which had an ultra-fine ferrite grain size of 3 mum (0.003 mm). The absorbed energy at 90 degreesC, the lowest temperature used, was as high as 100 J. It is suggested that this steel could be tough at temperatures even lower than -100 degreesC. A normalized specimen of the same steel, with a grain size of 7 mum, was tough at -60 degreesC, but brittle at -80 degreesC and -90 degreesC. The tensile strength of the TNCP material (640 MPa) was about 10 % higher than that of the normalized material (570 MPa).