Figure 3 : X-ray diffraction scan of high carbon steel compressed at room temperature showing the phase transformation of retained austenite to martensite.

From: Stability of retained austenite in high carbon steel under compressive stress: an investigation from macro to nano scale

Figure 3

Here γ, ε, α′ is denoted for the retained austenite, hcp martensite and bcc/bct martensite respectively.