Fig. 1 The form of the thermomechanical treatment, used to study 25°C/s Temperature 10 °C/s 250 - 350 °C 50 °C/s 1800 s 15s 4 - 200 MPa Stress 4 MPa Time Fig. 1 The form of the thermomechanical treatment, used to study stress-affected bainite. Fig. 2 Experimentally determined 0.2 % proof strength of the austenite as a function of test temperature.
Fig.3 Chemical and mechanical components of the driving force -1800 GMECH -1600 GCHEM -1400 -1200 Free energy / J mol-1 -1000 -800 -600 -400 Stored energy of bainite -200 250 º C 300 º C 350 º C Umemoto Shipway et al. [12] et al. [13] at 360 º C at 350 º C Fig.3 Chemical and mechanical components of the driving force for the growth of bainite.
(a) (b) Fig.4 Change in radial strain associated with the bainite transformation (a) at various transformation temperatures and (b) as a function of elastic stresses during transformation at 300 ºC.
Fig.5 Volume percent of bainite as a function of stress applied during the transformation, and the transformation temperature. Fig. 6 Transformation kinetics at various transformation temperatures and stresses.
in each case. The transformation is at 300 ºC. 4 MPa 200 MPa HV 777 HV 725 0.5 h HV 708 HV 644 1 h HV 579 HV 527 2 h 25m Fig. 7 Optical micrographs of bainitic microstructure transformed under the influence of an applied compressive stress. The stress axis is vertical in each case. The transformation is at 300 ºC.
4 MPa 200 MPa HV 409 HV 429 350 ºC, 5 h HV 508 HV 517 300 ºC, 5 h HV 574 HV 576 250 ºC, 12 h 25m Fig. 8 Optical micrographs of bainite transformed under the influence of an applied compressive stress. The stress axis is vertical in each case.
(a) 5 m (b) 5 m Fig. 9 Typical scanning electron micrographs of bainite transformed under the influence of an applied stress (a) 4 MPa and (b) 200 MPa at 300 °C for 5 hours. The stress axis is vertical in each case.
Fig.10 Approximate distribution of bainite sheaf traces with respect to longitudinal axis of sample.
(a) (b) 20m Fig.11 Orientation imaging maps of bainite formed at 300 ºC for 5 hours under the influence of an applied compressive stress of (a) 4 MPa and (b) 200 MPa. The stress axis is vertical in each case.