Moderating strain hardening rate to produce high ductility and high strength in a medium carbon TRIP steel

Figures & data

Figure 1 (a) Engineering stress - strain curves of the medium carbon TRIP steels after bainitic holding at 360°C, 400°C and 450°C. (b) Increasing strain hardening capacity with increasing bainitic holding temperature. (c, d) Comparison of mechanical properties in this study with the previously reported TRIP assisted steels in literatures [21, 25–35]. IA: intercritical annealing, FA: full austenitized, BH: bainitic holding.

Table 1. Mechanical properties of medium carbon TRIP steels after bainitic holding.

Bainite holding temperature °C	YS MPa	UTS MPa	(σt–σy) MPa	Uniform elongation %	Total elongation %	Toughness MPa
360	1010	1200	490	25	32	377
400	890	1220	793	38	44	495
450	510	1430	1320	28	29	339

Figure 2. SEM images of medium carbon TRIP steels. (a) 360°C specimen, (b) 400°C specimen and (c) 450°C specimen. (d) The corresponding XRD patterns, and inset showing the magnified (200)_Y peak. RA: retained austenite, B: bainite, F: ferrite, M: martensite.

Figure 3. Interface characterization of medium carbon TRIP steels. (a) 360°C specimen, (b) 400°C specimen, and (c) 450°C specimen. (d) The corresponding average grain sizes of RA (d). LAGB: low angle grain boundary, HAGB: high angle grain boundary.

Figure 4. Evolution of RA volume fraction as a function of true strain for medium carbon TRIP steels after bainitic holding at 360°C, 400°C, and 450°C.

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