Structure of steel with metastable austenite after thermomechanical treatment on different modes

The evolution of the structure of austenitized chromium-nickel-molybdenum trip-steel, depending on the degree of reduction during "warm" rolling, was investigated by optical and atomic force microscopy. The parameters of the main structural elements were measured - the sizes of austenite grains, martensite lamellas, the width and height of the twins. An increased content of the martensite phase on the surface is found in comparison with the bulk. This is consistent with the data of X-ray phase analysis and magnetic measurements. The degree of reduction does not significantly affect the content of the martensite phase, but the structure of martensite changes, becoming lath and highly dispersed. The work hardening of austenite during rolling leads to a fourfold increase in the yield strength in comparison with the initial austenitized state.

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