Nanostructure Formation and Carbides Dissolution in Rail Steel Deformed by High Pressure Torsion

Microstructural evolution of white and brown etching layers in pearlitic rail steels

“…Studies have shown that the formation of microstructures identical to those observed in WEL can be simulated using laboratory experiments such as rapid heating and cooling, machining, dry sliding wear testing, cold rolling in combination with heating with laser pulses and hard tuning [12,[22][23][24]. Carroll et al [6] demonstrated the formation of the WEL using spot welding and twin disk testing.…”

White etching structures in annealed 52100 bearing steel arising from high-pressure torsion tests

“…Both phenomena seem to be closely related to WEAs initiation and evolution [13][14][15][16][17][18][19]. Similar mechanisms have been suggested to explain the origin of some white microstructures encountered in pearlitic steels processed by High-Pressure Torsion tests (HPT) [20]. HPT has also been used recently to study the mechanical decomposition of cementite by SPD in a quenched/tempered AISI 52100 bearing steel and its role in the formation of WEAs [21] and to understand the nature and formation mechanism of White Etching Layers (WELs) in rail track steels [22].…”

“…Experimental evidence of this phenomenon has been used to account for the decomposition of spheroidal cementite immersed in a martensite matrix of an AISI 52100 bearing steel processed by HPT. The softer matrix flows around the harder spheroidal carbides, dragging C and Cr due to a wear effect registered at the matrix-cementite interface [20]. The plastic flow patterns around cementite particles resembled small coils which could be the origin of bigger vortices, higher C and Cr dissolution rates and hence, a possible driver for the initiation of WEAs.…”

“…and the generation of new structures by dynamic recrystallization [20]. These processes might be influenced by any heat generated by HPT such as that resulting from plastic deformation of the sample, sample / anvil friction, and flash formation.…”

Development of ultra-fine grained dual phase microalloyed steels through severe cold rolling and intercritical annealing

“…In recent years, ultra-fine grained (UFG) structural materials with mean grain size < 2 Pm have been studied extensively, because they are expected to provide superior mechanical properties. UFG steels with an average grain size below 1 m have been produced by severe plastic deformation (SPD) processes such as equal-channel angular pressing (ECAP) [10][11][12], accumulative roll bonding (ARB) [13][14][15], and high pressure torsion (HPT) [16][17][18][19]. Among the SPD techniques the accumulated plastic strain required to obtain submicron-sized grains is of the order of 3-4 for ECAP [10][11][12] and 5-6 for the ARB process [13][14][15].…”