Effects of Alloy System on Spontaneous Reverse Transformation Behavior in Steel

Reverse Transformation Caused by Temperature Increase due to Deformation Heating

“…Their low thermal diffusivity should cause the local temperature to rise rapidly at an early stage of deformation. SRT has been observed in rolling experiments [3][4][5] as well as in uniaxial compression tests. 1,2) In rolling experiments, the rolling reduction needed to cause SRT in Fe-0.3C-9Ni wt% steel was 70-90 % for a rolling speed of 50 m/min which corresponds to strain rate of around 10/s.…”

“…The ferrite (a) to austenite (g) reverse transformation can also be induced by an internal heat source, for example a temperature increase due to deformation heating. Spontaneous reverse transformation (SRT) [1][2][3][4][5] and transformed shear band (TSB) [6][7][8][9][10][11] are two such cases. SRT occurs due to adiabatic heating caused by a deformation at temperatures close to the austenite phase field.…”

“…SRT occurs due to adiabatic heating caused by a deformation at temperatures close to the austenite phase field. It has been observed in rolling experiments [3][4][5] as well as in uniaxial compression tests. 1,2) SRT has been developed as a microstructural control process to obtain ultrafine grained steels.…”

“…Ultra-fine martensite (aЈ) with a grain size of about 0.5 mm has been obtained through a→g→aЈ rapid phase transformation due to SRT in Fe-0.3C-9Ni wt% steel. [1][2][3][4][5] On the other hand, transformed shear band (TSB), known as one of the morphologies of adiabatic shear bands,…”

Grain Structure of Fe-0.3mass%C-9mass%Ni Steel Processed through .ALPHA..RAR..GAMMA..RAR..ALPHA.' Transformation Caused by Spontaneous Reverse Transformation

“…6) The new process, so called "Spontaneous Reverse Transformation (SRT)", has already been demonstrated. [7][8][9] Final martensite (aЈ) grain size (prior austenite grain size or packet size) with less than 1 mm has been obtained through a → g → aЈ transformation caused by SRT in Fe-0.3C-9Ni mass% steel. 7) Thus, SRT is the process to have an ultra refined austenite, and resulting ultra refined transformation products such as ferrite, bainite and martensite effectively.…”