Tensile Property of Submicrocrystalline Pure Fe Produced by HPT-Straining

The microstructure and the mechanical properties of pure Fe after HPT-straining at a rotation-speed of 0.2 rpm under a compression pressure of 5 GPa were investigated. The elongated grains with 300 nm thick and 600 nm long were observed at r = 1.5 mm away from the disk center regions after HPT-straining for 5 turns ( εeq = 45). The obtained Vickers microhardness in the submicrocrystalline Fe after 5 turns was around Hv 3.6 GPa. The engineering tensile strength and total elongation of the HPT-processed Fe for 10 turns were 1.9 GPa and 30 %. These facts suggest that HPT-straining leads to significant refinement of microstructure and increase in strength with good ductility.