Supplementary Information

Table S1. Composition of martensitic stainless steel MSS 420 and austenitic stainless steel ASS 301

C Si Mn Ni Cr Cu MoMSS 420 (M) 0.28 0.59 0.44 0.24 13.36 0.18 0.32 ASS 301 (A) 0.10 0.66 0.97 7.02 17.02 - -

Figure S1. (a) Microstructure of layered structure of multilayered steel, (b) 301 steel layer, (c) 420 steel layer, and (d) backscattered image from the interface showing the martensite laths and austenite grains.

Figure S2. Schematic of simulated cold rolling process of an MLS.

Figure S3. The tensile response of individual layers reported by Seok et al [4], which was extracted by nanoindentation and their comparison of the flow curve measured from standard tensile test of MLS.